Removed openssl, and curl, and added mbedded tls.curl-removal

Almost fully removed curl, needs more testing.

Fixed most issues, now trying to cross compile.

Fix?

Sigh.

1 files changed, 2814 insertions, 0 deletions

diff --git a/lib/mbedtls-2.27.0/library/rsa.c b/lib/mbedtls-2.27.0/library/rsa.c
new file mode 100644
index 0000000..268d025
--- /dev/null
+++ b/lib/mbedtls-2.27.0/library/rsa.c
@@ -0,0 +1,2814 @@
+/*
+ *  The RSA public-key cryptosystem
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/*
+ *  The following sources were referenced in the design of this implementation
+ *  of the RSA algorithm:
+ *
+ *  [1] A method for obtaining digital signatures and public-key cryptosystems
+ *      R Rivest, A Shamir, and L Adleman
+ *      http://people.csail.mit.edu/rivest/pubs.html#RSA78
+ *
+ *  [2] Handbook of Applied Cryptography - 1997, Chapter 8
+ *      Menezes, van Oorschot and Vanstone
+ *
+ *  [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks
+ *      Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and
+ *      Stefan Mangard
+ *      https://arxiv.org/abs/1702.08719v2
+ *
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_RSA_C)
+
+#include "mbedtls/rsa.h"
+#include "mbedtls/rsa_internal.h"
+#include "mbedtls/oid.h"
+#include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_PKCS1_V21)
+#include "mbedtls/md.h"
+#endif
+
+#if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) && !defined(__NetBSD__)
+#include <stdlib.h>
+#endif
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#define mbedtls_printf printf
+#define mbedtls_calloc calloc
+#define mbedtls_free   free
+#endif
+
+#if !defined(MBEDTLS_RSA_ALT)
+
+/* Parameter validation macros */
+#define RSA_VALIDATE_RET( cond )                                       \
+    MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_RSA_BAD_INPUT_DATA )
+#define RSA_VALIDATE( cond )                                           \
+    MBEDTLS_INTERNAL_VALIDATE( cond )
+
+#if defined(MBEDTLS_PKCS1_V15)
+/* constant-time buffer comparison */
+static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n )
+{
+    size_t i;
+    const unsigned char *A = (const unsigned char *) a;
+    const unsigned char *B = (const unsigned char *) b;
+    unsigned char diff = 0;
+
+    for( i = 0; i < n; i++ )
+        diff |= A[i] ^ B[i];
+
+    return( diff );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+int mbedtls_rsa_import( mbedtls_rsa_context *ctx,
+                        const mbedtls_mpi *N,
+                        const mbedtls_mpi *P, const mbedtls_mpi *Q,
+                        const mbedtls_mpi *D, const mbedtls_mpi *E )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    if( ( N != NULL && ( ret = mbedtls_mpi_copy( &ctx->N, N ) ) != 0 ) ||
+        ( P != NULL && ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ) ||
+        ( Q != NULL && ( ret = mbedtls_mpi_copy( &ctx->Q, Q ) ) != 0 ) ||
+        ( D != NULL && ( ret = mbedtls_mpi_copy( &ctx->D, D ) ) != 0 ) ||
+        ( E != NULL && ( ret = mbedtls_mpi_copy( &ctx->E, E ) ) != 0 ) )
+    {
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+    }
+
+    if( N != NULL )
+        ctx->len = mbedtls_mpi_size( &ctx->N );
+
+    return( 0 );
+}
+
+int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx,
+                            unsigned char const *N, size_t N_len,
+                            unsigned char const *P, size_t P_len,
+                            unsigned char const *Q, size_t Q_len,
+                            unsigned char const *D, size_t D_len,
+                            unsigned char const *E, size_t E_len )
+{
+    int ret = 0;
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    if( N != NULL )
+    {
+        MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->N, N, N_len ) );
+        ctx->len = mbedtls_mpi_size( &ctx->N );
+    }
+
+    if( P != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->P, P, P_len ) );
+
+    if( Q != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->Q, Q, Q_len ) );
+
+    if( D != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->D, D, D_len ) );
+
+    if( E != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->E, E, E_len ) );
+
+cleanup:
+
+    if( ret != 0 )
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+
+    return( 0 );
+}
+
+/*
+ * Checks whether the context fields are set in such a way
+ * that the RSA primitives will be able to execute without error.
+ * It does *not* make guarantees for consistency of the parameters.
+ */
+static int rsa_check_context( mbedtls_rsa_context const *ctx, int is_priv,
+                              int blinding_needed )
+{
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    /* blinding_needed is only used for NO_CRT to decide whether
+     * P,Q need to be present or not. */
+    ((void) blinding_needed);
+#endif
+
+    if( ctx->len != mbedtls_mpi_size( &ctx->N ) ||
+        ctx->len > MBEDTLS_MPI_MAX_SIZE )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+
+    /*
+     * 1. Modular exponentiation needs positive, odd moduli.
+     */
+
+    /* Modular exponentiation wrt. N is always used for
+     * RSA public key operations. */
+    if( mbedtls_mpi_cmp_int( &ctx->N, 0 ) <= 0 ||
+        mbedtls_mpi_get_bit( &ctx->N, 0 ) == 0  )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    /* Modular exponentiation for P and Q is only
+     * used for private key operations and if CRT
+     * is used. */
+    if( is_priv &&
+        ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 ||
+          mbedtls_mpi_get_bit( &ctx->P, 0 ) == 0 ||
+          mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ||
+          mbedtls_mpi_get_bit( &ctx->Q, 0 ) == 0  ) )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+#endif /* !MBEDTLS_RSA_NO_CRT */
+
+    /*
+     * 2. Exponents must be positive
+     */
+
+    /* Always need E for public key operations */
+    if( mbedtls_mpi_cmp_int( &ctx->E, 0 ) <= 0 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_RSA_NO_CRT)
+    /* For private key operations, use D or DP & DQ
+     * as (unblinded) exponents. */
+    if( is_priv && mbedtls_mpi_cmp_int( &ctx->D, 0 ) <= 0 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+#else
+    if( is_priv &&
+        ( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) <= 0 ||
+          mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) <= 0  ) )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+    /* Blinding shouldn't make exponents negative either,
+     * so check that P, Q >= 1 if that hasn't yet been
+     * done as part of 1. */
+#if defined(MBEDTLS_RSA_NO_CRT)
+    if( is_priv && blinding_needed &&
+        ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 ||
+          mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ) )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+#endif
+
+    /* It wouldn't lead to an error if it wasn't satisfied,
+     * but check for QP >= 1 nonetheless. */
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    if( is_priv &&
+        mbedtls_mpi_cmp_int( &ctx->QP, 0 ) <= 0 )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+#endif
+
+    return( 0 );
+}
+
+int mbedtls_rsa_complete( mbedtls_rsa_context *ctx )
+{
+    int ret = 0;
+    int have_N, have_P, have_Q, have_D, have_E;
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    int have_DP, have_DQ, have_QP;
+#endif
+    int n_missing, pq_missing, d_missing, is_pub, is_priv;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 );
+    have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 );
+    have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 );
+    have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 );
+    have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    have_DP = ( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) != 0 );
+    have_DQ = ( mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) != 0 );
+    have_QP = ( mbedtls_mpi_cmp_int( &ctx->QP, 0 ) != 0 );
+#endif
+
+    /*
+     * Check whether provided parameters are enough
+     * to deduce all others. The following incomplete
+     * parameter sets for private keys are supported:
+     *
+     * (1) P, Q missing.
+     * (2) D and potentially N missing.
+     *
+     */
+
+    n_missing  =              have_P &&  have_Q &&  have_D && have_E;
+    pq_missing =   have_N && !have_P && !have_Q &&  have_D && have_E;
+    d_missing  =              have_P &&  have_Q && !have_D && have_E;
+    is_pub     =   have_N && !have_P && !have_Q && !have_D && have_E;
+
+    /* These three alternatives are mutually exclusive */
+    is_priv = n_missing || pq_missing || d_missing;
+
+    if( !is_priv && !is_pub )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    /*
+     * Step 1: Deduce N if P, Q are provided.
+     */
+
+    if( !have_N && have_P && have_Q )
+    {
+        if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P,
+                                         &ctx->Q ) ) != 0 )
+        {
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+        }
+
+        ctx->len = mbedtls_mpi_size( &ctx->N );
+    }
+
+    /*
+     * Step 2: Deduce and verify all remaining core parameters.
+     */
+
+    if( pq_missing )
+    {
+        ret = mbedtls_rsa_deduce_primes( &ctx->N, &ctx->E, &ctx->D,
+                                         &ctx->P, &ctx->Q );
+        if( ret != 0 )
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+
+    }
+    else if( d_missing )
+    {
+        if( ( ret = mbedtls_rsa_deduce_private_exponent( &ctx->P,
+                                                         &ctx->Q,
+                                                         &ctx->E,
+                                                         &ctx->D ) ) != 0 )
+        {
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+        }
+    }
+
+    /*
+     * Step 3: Deduce all additional parameters specific
+     *         to our current RSA implementation.
+     */
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    if( is_priv && ! ( have_DP && have_DQ && have_QP ) )
+    {
+        ret = mbedtls_rsa_deduce_crt( &ctx->P,  &ctx->Q,  &ctx->D,
+                                      &ctx->DP, &ctx->DQ, &ctx->QP );
+        if( ret != 0 )
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+    }
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+    /*
+     * Step 3: Basic sanity checks
+     */
+
+    return( rsa_check_context( ctx, is_priv, 1 ) );
+}
+
+int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx,
+                            unsigned char *N, size_t N_len,
+                            unsigned char *P, size_t P_len,
+                            unsigned char *Q, size_t Q_len,
+                            unsigned char *D, size_t D_len,
+                            unsigned char *E, size_t E_len )
+{
+    int ret = 0;
+    int is_priv;
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    /* Check if key is private or public */
+    is_priv =
+        mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
+
+    if( !is_priv )
+    {
+        /* If we're trying to export private parameters for a public key,
+         * something must be wrong. */
+        if( P != NULL || Q != NULL || D != NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    }
+
+    if( N != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->N, N, N_len ) );
+
+    if( P != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->P, P, P_len ) );
+
+    if( Q != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->Q, Q, Q_len ) );
+
+    if( D != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->D, D, D_len ) );
+
+    if( E != NULL )
+        MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->E, E, E_len ) );
+
+cleanup:
+
+    return( ret );
+}
+
+int mbedtls_rsa_export( const mbedtls_rsa_context *ctx,
+                        mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q,
+                        mbedtls_mpi *D, mbedtls_mpi *E )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    int is_priv;
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    /* Check if key is private or public */
+    is_priv =
+        mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
+
+    if( !is_priv )
+    {
+        /* If we're trying to export private parameters for a public key,
+         * something must be wrong. */
+        if( P != NULL || Q != NULL || D != NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    }
+
+    /* Export all requested core parameters. */
+
+    if( ( N != NULL && ( ret = mbedtls_mpi_copy( N, &ctx->N ) ) != 0 ) ||
+        ( P != NULL && ( ret = mbedtls_mpi_copy( P, &ctx->P ) ) != 0 ) ||
+        ( Q != NULL && ( ret = mbedtls_mpi_copy( Q, &ctx->Q ) ) != 0 ) ||
+        ( D != NULL && ( ret = mbedtls_mpi_copy( D, &ctx->D ) ) != 0 ) ||
+        ( E != NULL && ( ret = mbedtls_mpi_copy( E, &ctx->E ) ) != 0 ) )
+    {
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Export CRT parameters
+ * This must also be implemented if CRT is not used, for being able to
+ * write DER encoded RSA keys. The helper function mbedtls_rsa_deduce_crt
+ * can be used in this case.
+ */
+int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx,
+                            mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    int is_priv;
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    /* Check if key is private or public */
+    is_priv =
+        mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
+        mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
+
+    if( !is_priv )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    /* Export all requested blinding parameters. */
+    if( ( DP != NULL && ( ret = mbedtls_mpi_copy( DP, &ctx->DP ) ) != 0 ) ||
+        ( DQ != NULL && ( ret = mbedtls_mpi_copy( DQ, &ctx->DQ ) ) != 0 ) ||
+        ( QP != NULL && ( ret = mbedtls_mpi_copy( QP, &ctx->QP ) ) != 0 ) )
+    {
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+    }
+#else
+    if( ( ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
+                                        DP, DQ, QP ) ) != 0 )
+    {
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
+    }
+#endif
+
+    return( 0 );
+}
+
+/*
+ * Initialize an RSA context
+ */
+void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
+               int padding,
+               int hash_id )
+{
+    RSA_VALIDATE( ctx != NULL );
+    RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 ||
+                  padding == MBEDTLS_RSA_PKCS_V21 );
+
+    memset( ctx, 0, sizeof( mbedtls_rsa_context ) );
+
+    mbedtls_rsa_set_padding( ctx, padding, hash_id );
+
+#if defined(MBEDTLS_THREADING_C)
+    /* Set ctx->ver to nonzero to indicate that the mutex has been
+     * initialized and will need to be freed. */
+    ctx->ver = 1;
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
+}
+
+/*
+ * Set padding for an existing RSA context
+ */
+void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding,
+                              int hash_id )
+{
+    RSA_VALIDATE( ctx != NULL );
+    RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 ||
+                  padding == MBEDTLS_RSA_PKCS_V21 );
+
+    ctx->padding = padding;
+    ctx->hash_id = hash_id;
+}
+
+/*
+ * Get length in bytes of RSA modulus
+ */
+
+size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx )
+{
+    return( ctx->len );
+}
+
+
+#if defined(MBEDTLS_GENPRIME)
+
+/*
+ * Generate an RSA keypair
+ *
+ * This generation method follows the RSA key pair generation procedure of
+ * FIPS 186-4 if 2^16 < exponent < 2^256 and nbits = 2048 or nbits = 3072.
+ */
+int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
+                 int (*f_rng)(void *, unsigned char *, size_t),
+                 void *p_rng,
+                 unsigned int nbits, int exponent )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_mpi H, G, L;
+    int prime_quality = 0;
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( f_rng != NULL );
+
+    /*
+     * If the modulus is 1024 bit long or shorter, then the security strength of
+     * the RSA algorithm is less than or equal to 80 bits and therefore an error
+     * rate of 2^-80 is sufficient.
+     */
+    if( nbits > 1024 )
+        prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR;
+
+    mbedtls_mpi_init( &H );
+    mbedtls_mpi_init( &G );
+    mbedtls_mpi_init( &L );
+
+    if( nbits < 128 || exponent < 3 || nbits % 2 != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+        goto cleanup;
+    }
+
+    /*
+     * find primes P and Q with Q < P so that:
+     * 1.  |P-Q| > 2^( nbits / 2 - 100 )
+     * 2.  GCD( E, (P-1)*(Q-1) ) == 1
+     * 3.  E^-1 mod LCM(P-1, Q-1) > 2^( nbits / 2 )
+     */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) );
+
+    do
+    {
+        MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1,
+                                                prime_quality, f_rng, p_rng ) );
+
+        MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1,
+                                                prime_quality, f_rng, p_rng ) );
+
+        /* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &H, &ctx->P, &ctx->Q ) );
+        if( mbedtls_mpi_bitlen( &H ) <= ( ( nbits >= 200 ) ? ( ( nbits >> 1 ) - 99 ) : 0 ) )
+            continue;
+
+        /* not required by any standards, but some users rely on the fact that P > Q */
+        if( H.s < 0 )
+            mbedtls_mpi_swap( &ctx->P, &ctx->Q );
+
+        /* Temporarily replace P,Q by P-1, Q-1 */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->P, &ctx->P, 1 ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->Q, &ctx->Q, 1 ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &ctx->P, &ctx->Q ) );
+
+        /* check GCD( E, (P-1)*(Q-1) ) == 1 (FIPS 186-4 §B.3.1 criterion 2(a)) */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H  ) );
+        if( mbedtls_mpi_cmp_int( &G, 1 ) != 0 )
+            continue;
+
+        /* compute smallest possible D = E^-1 mod LCM(P-1, Q-1) (FIPS 186-4 §B.3.1 criterion 3(b)) */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->P, &ctx->Q ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L, NULL, &H, &G ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D, &ctx->E, &L ) );
+
+        if( mbedtls_mpi_bitlen( &ctx->D ) <= ( ( nbits + 1 ) / 2 ) ) // (FIPS 186-4 §B.3.1 criterion 3(a))
+            continue;
+
+        break;
+    }
+    while( 1 );
+
+    /* Restore P,Q */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->P,  &ctx->P, 1 ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->Q,  &ctx->Q, 1 ) );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
+
+    ctx->len = mbedtls_mpi_size( &ctx->N );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    /*
+     * DP = D mod (P - 1)
+     * DQ = D mod (Q - 1)
+     * QP = Q^-1 mod P
+     */
+    MBEDTLS_MPI_CHK( mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
+                                             &ctx->DP, &ctx->DQ, &ctx->QP ) );
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+    /* Double-check */
+    MBEDTLS_MPI_CHK( mbedtls_rsa_check_privkey( ctx ) );
+
+cleanup:
+
+    mbedtls_mpi_free( &H );
+    mbedtls_mpi_free( &G );
+    mbedtls_mpi_free( &L );
+
+    if( ret != 0 )
+    {
+        mbedtls_rsa_free( ctx );
+
+        if( ( -ret & ~0x7f ) == 0 )
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_KEY_GEN_FAILED, ret );
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+#endif /* MBEDTLS_GENPRIME */
+
+/*
+ * Check a public RSA key
+ */
+int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx )
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) != 0 )
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+
+    if( mbedtls_mpi_bitlen( &ctx->N ) < 128 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    if( mbedtls_mpi_get_bit( &ctx->E, 0 ) == 0 ||
+        mbedtls_mpi_bitlen( &ctx->E )     < 2  ||
+        mbedtls_mpi_cmp_mpi( &ctx->E, &ctx->N ) >= 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Check for the consistency of all fields in an RSA private key context
+ */
+int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+
+    if( mbedtls_rsa_check_pubkey( ctx ) != 0 ||
+        rsa_check_context( ctx, 1 /* private */, 1 /* blinding */ ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    if( mbedtls_rsa_validate_params( &ctx->N, &ctx->P, &ctx->Q,
+                                     &ctx->D, &ctx->E, NULL, NULL ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    else if( mbedtls_rsa_validate_crt( &ctx->P, &ctx->Q, &ctx->D,
+                                       &ctx->DP, &ctx->DQ, &ctx->QP ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+#endif
+
+    return( 0 );
+}
+
+/*
+ * Check if contexts holding a public and private key match
+ */
+int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub,
+                                const mbedtls_rsa_context *prv )
+{
+    RSA_VALIDATE_RET( pub != NULL );
+    RSA_VALIDATE_RET( prv != NULL );
+
+    if( mbedtls_rsa_check_pubkey( pub )  != 0 ||
+        mbedtls_rsa_check_privkey( prv ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    if( mbedtls_mpi_cmp_mpi( &pub->N, &prv->N ) != 0 ||
+        mbedtls_mpi_cmp_mpi( &pub->E, &prv->E ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Do an RSA public key operation
+ */
+int mbedtls_rsa_public( mbedtls_rsa_context *ctx,
+                const unsigned char *input,
+                unsigned char *output )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t olen;
+    mbedtls_mpi T;
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( input != NULL );
+    RSA_VALIDATE_RET( output != NULL );
+
+    if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    mbedtls_mpi_init( &T );
+
+#if defined(MBEDTLS_THREADING_C)
+    if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
+        return( ret );
+#endif
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) );
+
+    if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
+    {
+        ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
+        goto cleanup;
+    }
+
+    olen = ctx->len;
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) );
+
+cleanup:
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
+        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+#endif
+
+    mbedtls_mpi_free( &T );
+
+    if( ret != 0 )
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_PUBLIC_FAILED, ret ) );
+
+    return( 0 );
+}
+
+/*
+ * Generate or update blinding values, see section 10 of:
+ *  KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
+ *  DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer
+ *  Berlin Heidelberg, 1996. p. 104-113.
+ */
+static int rsa_prepare_blinding( mbedtls_rsa_context *ctx,
+                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
+{
+    int ret, count = 0;
+    mbedtls_mpi R;
+
+    mbedtls_mpi_init( &R );
+
+    if( ctx->Vf.p != NULL )
+    {
+        /* We already have blinding values, just update them by squaring */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) );
+
+        goto cleanup;
+    }
+
+    /* Unblinding value: Vf = random number, invertible mod N */
+    do {
+        if( count++ > 10 )
+        {
+            ret = MBEDTLS_ERR_RSA_RNG_FAILED;
+            goto cleanup;
+        }
+
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) );
+
+        /* Compute Vf^-1 as R * (R Vf)^-1 to avoid leaks from inv_mod. */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, ctx->len - 1, f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vf, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
+
+        /* At this point, Vi is invertible mod N if and only if both Vf and R
+         * are invertible mod N. If one of them isn't, we don't need to know
+         * which one, we just loop and choose new values for both of them.
+         * (Each iteration succeeds with overwhelming probability.) */
+        ret = mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vi, &ctx->N );
+        if( ret != 0 && ret != MBEDTLS_ERR_MPI_NOT_ACCEPTABLE )
+            goto cleanup;
+
+    } while( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
+
+    /* Finish the computation of Vf^-1 = R * (R Vf)^-1 */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &R ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
+
+    /* Blinding value: Vi = Vf^(-e) mod N
+     * (Vi already contains Vf^-1 at this point) */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) );
+
+
+cleanup:
+    mbedtls_mpi_free( &R );
+
+    return( ret );
+}
+
+/*
+ * Exponent blinding supposed to prevent side-channel attacks using multiple
+ * traces of measurements to recover the RSA key. The more collisions are there,
+ * the more bits of the key can be recovered. See [3].
+ *
+ * Collecting n collisions with m bit long blinding value requires 2^(m-m/n)
+ * observations on avarage.
+ *
+ * For example with 28 byte blinding to achieve 2 collisions the adversary has
+ * to make 2^112 observations on avarage.
+ *
+ * (With the currently (as of 2017 April) known best algorithms breaking 2048
+ * bit RSA requires approximately as much time as trying out 2^112 random keys.
+ * Thus in this sense with 28 byte blinding the security is not reduced by
+ * side-channel attacks like the one in [3])
+ *
+ * This countermeasure does not help if the key recovery is possible with a
+ * single trace.
+ */
+#define RSA_EXPONENT_BLINDING 28
+
+/*
+ * Do an RSA private key operation
+ */
+int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
+                 int (*f_rng)(void *, unsigned char *, size_t),
+                 void *p_rng,
+                 const unsigned char *input,
+                 unsigned char *output )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t olen;
+
+    /* Temporary holding the result */
+    mbedtls_mpi T;
+
+    /* Temporaries holding P-1, Q-1 and the
+     * exponent blinding factor, respectively. */
+    mbedtls_mpi P1, Q1, R;
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    /* Temporaries holding the results mod p resp. mod q. */
+    mbedtls_mpi TP, TQ;
+
+    /* Temporaries holding the blinded exponents for
+     * the mod p resp. mod q computation (if used). */
+    mbedtls_mpi DP_blind, DQ_blind;
+
+    /* Pointers to actual exponents to be used - either the unblinded
+     * or the blinded ones, depending on the presence of a PRNG. */
+    mbedtls_mpi *DP = &ctx->DP;
+    mbedtls_mpi *DQ = &ctx->DQ;
+#else
+    /* Temporary holding the blinded exponent (if used). */
+    mbedtls_mpi D_blind;
+
+    /* Pointer to actual exponent to be used - either the unblinded
+     * or the blinded one, depending on the presence of a PRNG. */
+    mbedtls_mpi *D = &ctx->D;
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+    /* Temporaries holding the initial input and the double
+     * checked result; should be the same in the end. */
+    mbedtls_mpi I, C;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( input  != NULL );
+    RSA_VALIDATE_RET( output != NULL );
+
+    if( rsa_check_context( ctx, 1             /* private key checks */,
+                                f_rng != NULL /* blinding y/n       */ ) != 0 )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+
+#if defined(MBEDTLS_THREADING_C)
+    if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
+        return( ret );
+#endif
+
+    /* MPI Initialization */
+    mbedtls_mpi_init( &T );
+
+    mbedtls_mpi_init( &P1 );
+    mbedtls_mpi_init( &Q1 );
+    mbedtls_mpi_init( &R );
+
+    if( f_rng != NULL )
+    {
+#if defined(MBEDTLS_RSA_NO_CRT)
+        mbedtls_mpi_init( &D_blind );
+#else
+        mbedtls_mpi_init( &DP_blind );
+        mbedtls_mpi_init( &DQ_blind );
+#endif
+    }
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ );
+#endif
+
+    mbedtls_mpi_init( &I );
+    mbedtls_mpi_init( &C );
+
+    /* End of MPI initialization */
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) );
+    if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
+    {
+        ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
+        goto cleanup;
+    }
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) );
+
+    if( f_rng != NULL )
+    {
+        /*
+         * Blinding
+         * T = T * Vi mod N
+         */
+        MBEDTLS_MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vi ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) );
+
+        /*
+         * Exponent blinding
+         */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
+
+#if defined(MBEDTLS_RSA_NO_CRT)
+        /*
+         * D_blind = ( P - 1 ) * ( Q - 1 ) * R + D
+         */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
+                         f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &P1, &Q1 ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &D_blind, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &D_blind, &D_blind, &ctx->D ) );
+
+        D = &D_blind;
+#else
+        /*
+         * DP_blind = ( P - 1 ) * R + DP
+         */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
+                         f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DP_blind, &P1, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DP_blind, &DP_blind,
+                    &ctx->DP ) );
+
+        DP = &DP_blind;
+
+        /*
+         * DQ_blind = ( Q - 1 ) * R + DQ
+         */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
+                         f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DQ_blind, &Q1, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DQ_blind, &DQ_blind,
+                    &ctx->DQ ) );
+
+        DQ = &DQ_blind;
+#endif /* MBEDTLS_RSA_NO_CRT */
+    }
+
+#if defined(MBEDTLS_RSA_NO_CRT)
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) );
+#else
+    /*
+     * Faster decryption using the CRT
+     *
+     * TP = input ^ dP mod P
+     * TQ = input ^ dQ mod Q
+     */
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TP, &T, DP, &ctx->P, &ctx->RP ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TQ, &T, DQ, &ctx->Q, &ctx->RQ ) );
+
+    /*
+     * T = (TP - TQ) * (Q^-1 mod P) mod P
+     */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &TP, &TQ ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->QP ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &TP, &ctx->P ) );
+
+    /*
+     * T = TQ + T * Q
+     */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->Q ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) );
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+    if( f_rng != NULL )
+    {
+        /*
+         * Unblind
+         * T = T * Vf mod N
+         */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) );
+    }
+
+    /* Verify the result to prevent glitching attacks. */
+    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E,
+                                          &ctx->N, &ctx->RN ) );
+    if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
+        goto cleanup;
+    }
+
+    olen = ctx->len;
+    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) );
+
+cleanup:
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
+        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+#endif
+
+    mbedtls_mpi_free( &P1 );
+    mbedtls_mpi_free( &Q1 );
+    mbedtls_mpi_free( &R );
+
+    if( f_rng != NULL )
+    {
+#if defined(MBEDTLS_RSA_NO_CRT)
+        mbedtls_mpi_free( &D_blind );
+#else
+        mbedtls_mpi_free( &DP_blind );
+        mbedtls_mpi_free( &DQ_blind );
+#endif
+    }
+
+    mbedtls_mpi_free( &T );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ );
+#endif
+
+    mbedtls_mpi_free( &C );
+    mbedtls_mpi_free( &I );
+
+    if( ret != 0 && ret >= -0x007f )
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_PRIVATE_FAILED, ret ) );
+
+    return( ret );
+}
+
+#if defined(MBEDTLS_PKCS1_V21)
+/**
+ * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer.
+ *
+ * \param dst       buffer to mask
+ * \param dlen      length of destination buffer
+ * \param src       source of the mask generation
+ * \param slen      length of the source buffer
+ * \param md_ctx    message digest context to use
+ */
+static int mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src,
+                      size_t slen, mbedtls_md_context_t *md_ctx )
+{
+    unsigned char mask[MBEDTLS_MD_MAX_SIZE];
+    unsigned char counter[4];
+    unsigned char *p;
+    unsigned int hlen;
+    size_t i, use_len;
+    int ret = 0;
+
+    memset( mask, 0, MBEDTLS_MD_MAX_SIZE );
+    memset( counter, 0, 4 );
+
+    hlen = mbedtls_md_get_size( md_ctx->md_info );
+
+    /* Generate and apply dbMask */
+    p = dst;
+
+    while( dlen > 0 )
+    {
+        use_len = hlen;
+        if( dlen < hlen )
+            use_len = dlen;
+
+        if( ( ret = mbedtls_md_starts( md_ctx ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md_update( md_ctx, src, slen ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md_update( md_ctx, counter, 4 ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md_finish( md_ctx, mask ) ) != 0 )
+            goto exit;
+
+        for( i = 0; i < use_len; ++i )
+            *p++ ^= mask[i];
+
+        counter[3]++;
+
+        dlen -= use_len;
+    }
+
+exit:
+    mbedtls_platform_zeroize( mask, sizeof( mask ) );
+
+    return( ret );
+}
+#endif /* MBEDTLS_PKCS1_V21 */
+
+#if defined(MBEDTLS_PKCS1_V21)
+/*
+ * Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function
+ */
+int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
+                            int (*f_rng)(void *, unsigned char *, size_t),
+                            void *p_rng,
+                            int mode,
+                            const unsigned char *label, size_t label_len,
+                            size_t ilen,
+                            const unsigned char *input,
+                            unsigned char *output )
+{
+    size_t olen;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *p = output;
+    unsigned int hlen;
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output != NULL );
+    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+    RSA_VALIDATE_RET( label_len == 0 || label != NULL );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    if( f_rng == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
+    if( md_info == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    olen = ctx->len;
+    hlen = mbedtls_md_get_size( md_info );
+
+    /* first comparison checks for overflow */
+    if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    memset( output, 0, olen );
+
+    *p++ = 0;
+
+    /* Generate a random octet string seed */
+    if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 )
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
+
+    p += hlen;
+
+    /* Construct DB */
+    if( ( ret = mbedtls_md( md_info, label, label_len, p ) ) != 0 )
+        return( ret );
+    p += hlen;
+    p += olen - 2 * hlen - 2 - ilen;
+    *p++ = 1;
+    if( ilen != 0 )
+        memcpy( p, input, ilen );
+
+    mbedtls_md_init( &md_ctx );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+        goto exit;
+
+    /* maskedDB: Apply dbMask to DB */
+    if( ( ret = mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,
+                          &md_ctx ) ) != 0 )
+        goto exit;
+
+    /* maskedSeed: Apply seedMask to seed */
+    if( ( ret = mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1,
+                          &md_ctx ) ) != 0 )
+        goto exit;
+
+exit:
+    mbedtls_md_free( &md_ctx );
+
+    if( ret != 0 )
+        return( ret );
+
+    return( ( mode == MBEDTLS_RSA_PUBLIC )
+            ? mbedtls_rsa_public(  ctx, output, output )
+            : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) );
+}
+#endif /* MBEDTLS_PKCS1_V21 */
+
+#if defined(MBEDTLS_PKCS1_V15)
+/*
+ * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function
+ */
+int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
+                                 int (*f_rng)(void *, unsigned char *, size_t),
+                                 void *p_rng,
+                                 int mode, size_t ilen,
+                                 const unsigned char *input,
+                                 unsigned char *output )
+{
+    size_t nb_pad, olen;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *p = output;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output != NULL );
+    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    olen = ctx->len;
+
+    /* first comparison checks for overflow */
+    if( ilen + 11 < ilen || olen < ilen + 11 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    nb_pad = olen - 3 - ilen;
+
+    *p++ = 0;
+    if( mode == MBEDTLS_RSA_PUBLIC )
+    {
+        if( f_rng == NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        *p++ = MBEDTLS_RSA_CRYPT;
+
+        while( nb_pad-- > 0 )
+        {
+            int rng_dl = 100;
+
+            do {
+                ret = f_rng( p_rng, p, 1 );
+            } while( *p == 0 && --rng_dl && ret == 0 );
+
+            /* Check if RNG failed to generate data */
+            if( rng_dl == 0 || ret != 0 )
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
+
+            p++;
+        }
+    }
+    else
+    {
+        *p++ = MBEDTLS_RSA_SIGN;
+
+        while( nb_pad-- > 0 )
+            *p++ = 0xFF;
+    }
+
+    *p++ = 0;
+    if( ilen != 0 )
+        memcpy( p, input, ilen );
+
+    return( ( mode == MBEDTLS_RSA_PUBLIC )
+            ? mbedtls_rsa_public(  ctx, output, output )
+            : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+/*
+ * Add the message padding, then do an RSA operation
+ */
+int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
+                       int (*f_rng)(void *, unsigned char *, size_t),
+                       void *p_rng,
+                       int mode, size_t ilen,
+                       const unsigned char *input,
+                       unsigned char *output )
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output != NULL );
+    RSA_VALIDATE_RET( ilen == 0 || input != NULL );
+
+    switch( ctx->padding )
+    {
+#if defined(MBEDTLS_PKCS1_V15)
+        case MBEDTLS_RSA_PKCS_V15:
+            return mbedtls_rsa_rsaes_pkcs1_v15_encrypt( ctx, f_rng, p_rng, mode, ilen,
+                                                input, output );
+#endif
+
+#if defined(MBEDTLS_PKCS1_V21)
+        case MBEDTLS_RSA_PKCS_V21:
+            return mbedtls_rsa_rsaes_oaep_encrypt( ctx, f_rng, p_rng, mode, NULL, 0,
+                                           ilen, input, output );
+#endif
+
+        default:
+            return( MBEDTLS_ERR_RSA_INVALID_PADDING );
+    }
+}
+
+#if defined(MBEDTLS_PKCS1_V21)
+/*
+ * Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function
+ */
+int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
+                            int (*f_rng)(void *, unsigned char *, size_t),
+                            void *p_rng,
+                            int mode,
+                            const unsigned char *label, size_t label_len,
+                            size_t *olen,
+                            const unsigned char *input,
+                            unsigned char *output,
+                            size_t output_max_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t ilen, i, pad_len;
+    unsigned char *p, bad, pad_done;
+    unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+    unsigned char lhash[MBEDTLS_MD_MAX_SIZE];
+    unsigned int hlen;
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+    RSA_VALIDATE_RET( label_len == 0 || label != NULL );
+    RSA_VALIDATE_RET( input != NULL );
+    RSA_VALIDATE_RET( olen != NULL );
+
+    /*
+     * Parameters sanity checks
+     */
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    ilen = ctx->len;
+
+    if( ilen < 16 || ilen > sizeof( buf ) )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
+    if( md_info == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    hlen = mbedtls_md_get_size( md_info );
+
+    // checking for integer underflow
+    if( 2 * hlen + 2 > ilen )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    /*
+     * RSA operation
+     */
+    ret = ( mode == MBEDTLS_RSA_PUBLIC )
+          ? mbedtls_rsa_public(  ctx, input, buf )
+          : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf );
+
+    if( ret != 0 )
+        goto cleanup;
+
+    /*
+     * Unmask data and generate lHash
+     */
+    mbedtls_md_init( &md_ctx );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        goto cleanup;
+    }
+
+    /* seed: Apply seedMask to maskedSeed */
+    if( ( ret = mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
+                          &md_ctx ) ) != 0 ||
+    /* DB: Apply dbMask to maskedDB */
+        ( ret = mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
+                          &md_ctx ) ) != 0 )
+    {
+        mbedtls_md_free( &md_ctx );
+        goto cleanup;
+    }
+
+    mbedtls_md_free( &md_ctx );
+
+    /* Generate lHash */
+    if( ( ret = mbedtls_md( md_info, label, label_len, lhash ) ) != 0 )
+        goto cleanup;
+
+    /*
+     * Check contents, in "constant-time"
+     */
+    p = buf;
+    bad = 0;
+
+    bad |= *p++; /* First byte must be 0 */
+
+    p += hlen; /* Skip seed */
+
+    /* Check lHash */
+    for( i = 0; i < hlen; i++ )
+        bad |= lhash[i] ^ *p++;
+
+    /* Get zero-padding len, but always read till end of buffer
+     * (minus one, for the 01 byte) */
+    pad_len = 0;
+    pad_done = 0;
+    for( i = 0; i < ilen - 2 * hlen - 2; i++ )
+    {
+        pad_done |= p[i];
+        pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
+    }
+
+    p += pad_len;
+    bad |= *p++ ^ 0x01;
+
+    /*
+     * The only information "leaked" is whether the padding was correct or not
+     * (eg, no data is copied if it was not correct). This meets the
+     * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between
+     * the different error conditions.
+     */
+    if( bad != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
+        goto cleanup;
+    }
+
+    if( ilen - ( p - buf ) > output_max_len )
+    {
+        ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE;
+        goto cleanup;
+    }
+
+    *olen = ilen - (p - buf);
+    if( *olen != 0 )
+        memcpy( output, p, *olen );
+    ret = 0;
+
+cleanup:
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+    mbedtls_platform_zeroize( lhash, sizeof( lhash ) );
+
+    return( ret );
+}
+#endif /* MBEDTLS_PKCS1_V21 */
+
+#if defined(MBEDTLS_PKCS1_V15)
+/** Turn zero-or-nonzero into zero-or-all-bits-one, without branches.
+ *
+ * \param value     The value to analyze.
+ * \return          Zero if \p value is zero, otherwise all-bits-one.
+ */
+static unsigned all_or_nothing_int( unsigned value )
+{
+    /* MSVC has a warning about unary minus on unsigned, but this is
+     * well-defined and precisely what we want to do here */
+#if defined(_MSC_VER)
+#pragma warning( push )
+#pragma warning( disable : 4146 )
+#endif
+    return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) );
+#if defined(_MSC_VER)
+#pragma warning( pop )
+#endif
+}
+
+/** Check whether a size is out of bounds, without branches.
+ *
+ * This is equivalent to `size > max`, but is likely to be compiled to
+ * to code using bitwise operation rather than a branch.
+ *
+ * \param size      Size to check.
+ * \param max       Maximum desired value for \p size.
+ * \return          \c 0 if `size <= max`.
+ * \return          \c 1 if `size > max`.
+ */
+static unsigned size_greater_than( size_t size, size_t max )
+{
+    /* Return the sign bit (1 for negative) of (max - size). */
+    return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) );
+}
+
+/** Choose between two integer values, without branches.
+ *
+ * This is equivalent to `cond ? if1 : if0`, but is likely to be compiled
+ * to code using bitwise operation rather than a branch.
+ *
+ * \param cond      Condition to test.
+ * \param if1       Value to use if \p cond is nonzero.
+ * \param if0       Value to use if \p cond is zero.
+ * \return          \c if1 if \p cond is nonzero, otherwise \c if0.
+ */
+static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 )
+{
+    unsigned mask = all_or_nothing_int( cond );
+    return( ( mask & if1 ) | (~mask & if0 ) );
+}
+
+/** Shift some data towards the left inside a buffer without leaking
+ * the length of the data through side channels.
+ *
+ * `mem_move_to_left(start, total, offset)` is functionally equivalent to
+ * ```
+ * memmove(start, start + offset, total - offset);
+ * memset(start + offset, 0, total - offset);
+ * ```
+ * but it strives to use a memory access pattern (and thus total timing)
+ * that does not depend on \p offset. This timing independence comes at
+ * the expense of performance.
+ *
+ * \param start     Pointer to the start of the buffer.
+ * \param total     Total size of the buffer.
+ * \param offset    Offset from which to copy \p total - \p offset bytes.
+ */
+static void mem_move_to_left( void *start,
+                              size_t total,
+                              size_t offset )
+{
+    volatile unsigned char *buf = start;
+    size_t i, n;
+    if( total == 0 )
+        return;
+    for( i = 0; i < total; i++ )
+    {
+        unsigned no_op = size_greater_than( total - offset, i );
+        /* The first `total - offset` passes are a no-op. The last
+         * `offset` passes shift the data one byte to the left and
+         * zero out the last byte. */
+        for( n = 0; n < total - 1; n++ )
+        {
+            unsigned char current = buf[n];
+            unsigned char next = buf[n+1];
+            buf[n] = if_int( no_op, current, next );
+        }
+        buf[total-1] = if_int( no_op, buf[total-1], 0 );
+    }
+}
+
+/*
+ * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function
+ */
+int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
+                                 int (*f_rng)(void *, unsigned char *, size_t),
+                                 void *p_rng,
+                                 int mode, size_t *olen,
+                                 const unsigned char *input,
+                                 unsigned char *output,
+                                 size_t output_max_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t ilen, i, plaintext_max_size;
+    unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+    /* The following variables take sensitive values: their value must
+     * not leak into the observable behavior of the function other than
+     * the designated outputs (output, olen, return value). Otherwise
+     * this would open the execution of the function to
+     * side-channel-based variants of the Bleichenbacher padding oracle
+     * attack. Potential side channels include overall timing, memory
+     * access patterns (especially visible to an adversary who has access
+     * to a shared memory cache), and branches (especially visible to
+     * an adversary who has access to a shared code cache or to a shared
+     * branch predictor). */
+    size_t pad_count = 0;
+    unsigned bad = 0;
+    unsigned char pad_done = 0;
+    size_t plaintext_size = 0;
+    unsigned output_too_large;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+    RSA_VALIDATE_RET( input != NULL );
+    RSA_VALIDATE_RET( olen != NULL );
+
+    ilen = ctx->len;
+    plaintext_max_size = ( output_max_len > ilen - 11 ?
+                           ilen - 11 :
+                           output_max_len );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    if( ilen < 16 || ilen > sizeof( buf ) )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    ret = ( mode == MBEDTLS_RSA_PUBLIC )
+          ? mbedtls_rsa_public(  ctx, input, buf )
+          : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf );
+
+    if( ret != 0 )
+        goto cleanup;
+
+    /* Check and get padding length in constant time and constant
+     * memory trace. The first byte must be 0. */
+    bad |= buf[0];
+
+    if( mode == MBEDTLS_RSA_PRIVATE )
+    {
+        /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00
+         * where PS must be at least 8 nonzero bytes. */
+        bad |= buf[1] ^ MBEDTLS_RSA_CRYPT;
+
+        /* Read the whole buffer. Set pad_done to nonzero if we find
+         * the 0x00 byte and remember the padding length in pad_count. */
+        for( i = 2; i < ilen; i++ )
+        {
+            pad_done  |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1;
+            pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
+        }
+    }
+    else
+    {
+        /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00
+         * where PS must be at least 8 bytes with the value 0xFF. */
+        bad |= buf[1] ^ MBEDTLS_RSA_SIGN;
+
+        /* Read the whole buffer. Set pad_done to nonzero if we find
+         * the 0x00 byte and remember the padding length in pad_count.
+         * If there's a non-0xff byte in the padding, the padding is bad. */
+        for( i = 2; i < ilen; i++ )
+        {
+            pad_done |= if_int( buf[i], 0, 1 );
+            pad_count += if_int( pad_done, 0, 1 );
+            bad |= if_int( pad_done, 0, buf[i] ^ 0xFF );
+        }
+    }
+
+    /* If pad_done is still zero, there's no data, only unfinished padding. */
+    bad |= if_int( pad_done, 0, 1 );
+
+    /* There must be at least 8 bytes of padding. */
+    bad |= size_greater_than( 8, pad_count );
+
+    /* If the padding is valid, set plaintext_size to the number of
+     * remaining bytes after stripping the padding. If the padding
+     * is invalid, avoid leaking this fact through the size of the
+     * output: use the maximum message size that fits in the output
+     * buffer. Do it without branches to avoid leaking the padding
+     * validity through timing. RSA keys are small enough that all the
+     * size_t values involved fit in unsigned int. */
+    plaintext_size = if_int( bad,
+                             (unsigned) plaintext_max_size,
+                             (unsigned) ( ilen - pad_count - 3 ) );
+
+    /* Set output_too_large to 0 if the plaintext fits in the output
+     * buffer and to 1 otherwise. */
+    output_too_large = size_greater_than( plaintext_size,
+                                          plaintext_max_size );
+
+    /* Set ret without branches to avoid timing attacks. Return:
+     * - INVALID_PADDING if the padding is bad (bad != 0).
+     * - OUTPUT_TOO_LARGE if the padding is good but the decrypted
+     *   plaintext does not fit in the output buffer.
+     * - 0 if the padding is correct. */
+    ret = - (int) if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING,
+                  if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE,
+                          0 ) );
+
+    /* If the padding is bad or the plaintext is too large, zero the
+     * data that we're about to copy to the output buffer.
+     * We need to copy the same amount of data
+     * from the same buffer whether the padding is good or not to
+     * avoid leaking the padding validity through overall timing or
+     * through memory or cache access patterns. */
+    bad = all_or_nothing_int( bad | output_too_large );
+    for( i = 11; i < ilen; i++ )
+        buf[i] &= ~bad;
+
+    /* If the plaintext is too large, truncate it to the buffer size.
+     * Copy anyway to avoid revealing the length through timing, because
+     * revealing the length is as bad as revealing the padding validity
+     * for a Bleichenbacher attack. */
+    plaintext_size = if_int( output_too_large,
+                             (unsigned) plaintext_max_size,
+                             (unsigned) plaintext_size );
+
+    /* Move the plaintext to the leftmost position where it can start in
+     * the working buffer, i.e. make it start plaintext_max_size from
+     * the end of the buffer. Do this with a memory access trace that
+     * does not depend on the plaintext size. After this move, the
+     * starting location of the plaintext is no longer sensitive
+     * information. */
+    mem_move_to_left( buf + ilen - plaintext_max_size,
+                      plaintext_max_size,
+                      plaintext_max_size - plaintext_size );
+
+    /* Finally copy the decrypted plaintext plus trailing zeros into the output
+     * buffer. If output_max_len is 0, then output may be an invalid pointer
+     * and the result of memcpy() would be undefined; prevent undefined
+     * behavior making sure to depend only on output_max_len (the size of the
+     * user-provided output buffer), which is independent from plaintext
+     * length, validity of padding, success of the decryption, and other
+     * secrets. */
+    if( output_max_len != 0 )
+        memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size );
+
+    /* Report the amount of data we copied to the output buffer. In case
+     * of errors (bad padding or output too large), the value of *olen
+     * when this function returns is not specified. Making it equivalent
+     * to the good case limits the risks of leaking the padding validity. */
+    *olen = plaintext_size;
+
+cleanup:
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+
+    return( ret );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+/*
+ * Do an RSA operation, then remove the message padding
+ */
+int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx,
+                       int (*f_rng)(void *, unsigned char *, size_t),
+                       void *p_rng,
+                       int mode, size_t *olen,
+                       const unsigned char *input,
+                       unsigned char *output,
+                       size_t output_max_len)
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+    RSA_VALIDATE_RET( input != NULL );
+    RSA_VALIDATE_RET( olen != NULL );
+
+    switch( ctx->padding )
+    {
+#if defined(MBEDTLS_PKCS1_V15)
+        case MBEDTLS_RSA_PKCS_V15:
+            return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen,
+                                                input, output, output_max_len );
+#endif
+
+#if defined(MBEDTLS_PKCS1_V21)
+        case MBEDTLS_RSA_PKCS_V21:
+            return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0,
+                                           olen, input, output,
+                                           output_max_len );
+#endif
+
+        default:
+            return( MBEDTLS_ERR_RSA_INVALID_PADDING );
+    }
+}
+
+#if defined(MBEDTLS_PKCS1_V21)
+static int rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
+                         int (*f_rng)(void *, unsigned char *, size_t),
+                         void *p_rng,
+                         int mode,
+                         mbedtls_md_type_t md_alg,
+                         unsigned int hashlen,
+                         const unsigned char *hash,
+                         int saltlen,
+                         unsigned char *sig )
+{
+    size_t olen;
+    unsigned char *p = sig;
+    unsigned char *salt = NULL;
+    size_t slen, min_slen, hlen, offset = 0;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t msb;
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+    RSA_VALIDATE_RET( sig != NULL );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    if( f_rng == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    olen = ctx->len;
+
+    if( md_alg != MBEDTLS_MD_NONE )
+    {
+        /* Gather length of hash to sign */
+        md_info = mbedtls_md_info_from_type( md_alg );
+        if( md_info == NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        hashlen = mbedtls_md_get_size( md_info );
+    }
+
+    md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
+    if( md_info == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    hlen = mbedtls_md_get_size( md_info );
+
+    if (saltlen == MBEDTLS_RSA_SALT_LEN_ANY)
+    {
+       /* Calculate the largest possible salt length, up to the hash size.
+        * Normally this is the hash length, which is the maximum salt length
+        * according to FIPS 185-4 §5.5 (e) and common practice. If there is not
+        * enough room, use the maximum salt length that fits. The constraint is
+        * that the hash length plus the salt length plus 2 bytes must be at most
+        * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017
+        * (PKCS#1 v2.2) §9.1.1 step 3. */
+        min_slen = hlen - 2;
+        if( olen < hlen + min_slen + 2 )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+        else if( olen >= hlen + hlen + 2 )
+            slen = hlen;
+        else
+            slen = olen - hlen - 2;
+    }
+    else if ( (saltlen < 0) || (saltlen + hlen + 2 > olen) )
+    {
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+    else
+    {
+        slen = (size_t) saltlen;
+    }
+
+    memset( sig, 0, olen );
+
+    /* Note: EMSA-PSS encoding is over the length of N - 1 bits */
+    msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
+    p += olen - hlen - slen - 2;
+    *p++ = 0x01;
+
+    /* Generate salt of length slen in place in the encoded message */
+    salt = p;
+    if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 )
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
+
+    p += slen;
+
+    mbedtls_md_init( &md_ctx );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+        goto exit;
+
+    /* Generate H = Hash( M' ) */
+    if( ( ret = mbedtls_md_starts( &md_ctx ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_md_update( &md_ctx, p, 8 ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_md_update( &md_ctx, hash, hashlen ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_md_update( &md_ctx, salt, slen ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_md_finish( &md_ctx, p ) ) != 0 )
+        goto exit;
+
+    /* Compensate for boundary condition when applying mask */
+    if( msb % 8 == 0 )
+        offset = 1;
+
+    /* maskedDB: Apply dbMask to DB */
+    if( ( ret = mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen,
+                          &md_ctx ) ) != 0 )
+        goto exit;
+
+    msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
+    sig[0] &= 0xFF >> ( olen * 8 - msb );
+
+    p += hlen;
+    *p++ = 0xBC;
+
+exit:
+    mbedtls_md_free( &md_ctx );
+
+    if( ret != 0 )
+        return( ret );
+
+    return( ( mode == MBEDTLS_RSA_PUBLIC )
+            ? mbedtls_rsa_public(  ctx, sig, sig )
+            : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) );
+}
+
+/*
+ * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function with
+ * the option to pass in the salt length.
+ */
+int mbedtls_rsa_rsassa_pss_sign_ext( mbedtls_rsa_context *ctx,
+                         int (*f_rng)(void *, unsigned char *, size_t),
+                         void *p_rng,
+                         mbedtls_md_type_t md_alg,
+                         unsigned int hashlen,
+                         const unsigned char *hash,
+                         int saltlen,
+                         unsigned char *sig )
+{
+    return rsa_rsassa_pss_sign( ctx, f_rng, p_rng, MBEDTLS_RSA_PRIVATE, md_alg,
+                                hashlen, hash, saltlen, sig );
+}
+
+
+/*
+ * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function
+ */
+int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
+                         int (*f_rng)(void *, unsigned char *, size_t),
+                         void *p_rng,
+                         int mode,
+                         mbedtls_md_type_t md_alg,
+                         unsigned int hashlen,
+                         const unsigned char *hash,
+                         unsigned char *sig )
+{
+    return rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg,
+                                hashlen, hash, MBEDTLS_RSA_SALT_LEN_ANY, sig );
+}
+#endif /* MBEDTLS_PKCS1_V21 */
+
+#if defined(MBEDTLS_PKCS1_V15)
+/*
+ * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function
+ */
+
+/* Construct a PKCS v1.5 encoding of a hashed message
+ *
+ * This is used both for signature generation and verification.
+ *
+ * Parameters:
+ * - md_alg:  Identifies the hash algorithm used to generate the given hash;
+ *            MBEDTLS_MD_NONE if raw data is signed.
+ * - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE.
+ * - hash:    Buffer containing the hashed message or the raw data.
+ * - dst_len: Length of the encoded message.
+ * - dst:     Buffer to hold the encoded message.
+ *
+ * Assumptions:
+ * - hash has size hashlen if md_alg == MBEDTLS_MD_NONE.
+ * - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE.
+ * - dst points to a buffer of size at least dst_len.
+ *
+ */
+static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg,
+                                        unsigned int hashlen,
+                                        const unsigned char *hash,
+                                        size_t dst_len,
+                                        unsigned char *dst )
+{
+    size_t oid_size  = 0;
+    size_t nb_pad    = dst_len;
+    unsigned char *p = dst;
+    const char *oid  = NULL;
+
+    /* Are we signing hashed or raw data? */
+    if( md_alg != MBEDTLS_MD_NONE )
+    {
+        const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
+        if( md_info == NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        hashlen = mbedtls_md_get_size( md_info );
+
+        /* Double-check that 8 + hashlen + oid_size can be used as a
+         * 1-byte ASN.1 length encoding and that there's no overflow. */
+        if( 8 + hashlen + oid_size  >= 0x80         ||
+            10 + hashlen            <  hashlen      ||
+            10 + hashlen + oid_size <  10 + hashlen )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        /*
+         * Static bounds check:
+         * - Need 10 bytes for five tag-length pairs.
+         *   (Insist on 1-byte length encodings to protect against variants of
+         *    Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification)
+         * - Need hashlen bytes for hash
+         * - Need oid_size bytes for hash alg OID.
+         */
+        if( nb_pad < 10 + hashlen + oid_size )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+        nb_pad -= 10 + hashlen + oid_size;
+    }
+    else
+    {
+        if( nb_pad < hashlen )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        nb_pad -= hashlen;
+    }
+
+    /* Need space for signature header and padding delimiter (3 bytes),
+     * and 8 bytes for the minimal padding */
+    if( nb_pad < 3 + 8 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    nb_pad -= 3;
+
+    /* Now nb_pad is the amount of memory to be filled
+     * with padding, and at least 8 bytes long. */
+
+    /* Write signature header and padding */
+    *p++ = 0;
+    *p++ = MBEDTLS_RSA_SIGN;
+    memset( p, 0xFF, nb_pad );
+    p += nb_pad;
+    *p++ = 0;
+
+    /* Are we signing raw data? */
+    if( md_alg == MBEDTLS_MD_NONE )
+    {
+        memcpy( p, hash, hashlen );
+        return( 0 );
+    }
+
+    /* Signing hashed data, add corresponding ASN.1 structure
+     *
+     * DigestInfo ::= SEQUENCE {
+     *   digestAlgorithm DigestAlgorithmIdentifier,
+     *   digest Digest }
+     * DigestAlgorithmIdentifier ::= AlgorithmIdentifier
+     * Digest ::= OCTET STRING
+     *
+     * Schematic:
+     * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID  + LEN [ OID  ]
+     *                                 TAG-NULL + LEN [ NULL ] ]
+     *                 TAG-OCTET + LEN [ HASH ] ]
+     */
+    *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+    *p++ = (unsigned char)( 0x08 + oid_size + hashlen );
+    *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+    *p++ = (unsigned char)( 0x04 + oid_size );
+    *p++ = MBEDTLS_ASN1_OID;
+    *p++ = (unsigned char) oid_size;
+    memcpy( p, oid, oid_size );
+    p += oid_size;
+    *p++ = MBEDTLS_ASN1_NULL;
+    *p++ = 0x00;
+    *p++ = MBEDTLS_ASN1_OCTET_STRING;
+    *p++ = (unsigned char) hashlen;
+    memcpy( p, hash, hashlen );
+    p += hashlen;
+
+    /* Just a sanity-check, should be automatic
+     * after the initial bounds check. */
+    if( p != dst + dst_len )
+    {
+        mbedtls_platform_zeroize( dst, dst_len );
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Do an RSA operation to sign the message digest
+ */
+int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
+                               int (*f_rng)(void *, unsigned char *, size_t),
+                               void *p_rng,
+                               int mode,
+                               mbedtls_md_type_t md_alg,
+                               unsigned int hashlen,
+                               const unsigned char *hash,
+                               unsigned char *sig )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *sig_try = NULL, *verif = NULL;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+    RSA_VALIDATE_RET( sig != NULL );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    /*
+     * Prepare PKCS1-v1.5 encoding (padding and hash identifier)
+     */
+
+    if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash,
+                                             ctx->len, sig ) ) != 0 )
+        return( ret );
+
+    /*
+     * Call respective RSA primitive
+     */
+
+    if( mode == MBEDTLS_RSA_PUBLIC )
+    {
+        /* Skip verification on a public key operation */
+        return( mbedtls_rsa_public( ctx, sig, sig ) );
+    }
+
+    /* Private key operation
+     *
+     * In order to prevent Lenstra's attack, make the signature in a
+     * temporary buffer and check it before returning it.
+     */
+
+    sig_try = mbedtls_calloc( 1, ctx->len );
+    if( sig_try == NULL )
+        return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
+
+    verif = mbedtls_calloc( 1, ctx->len );
+    if( verif == NULL )
+    {
+        mbedtls_free( sig_try );
+        return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
+    }
+
+    MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) );
+
+    if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
+        goto cleanup;
+    }
+
+    memcpy( sig, sig_try, ctx->len );
+
+cleanup:
+    mbedtls_free( sig_try );
+    mbedtls_free( verif );
+
+    return( ret );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+/*
+ * Do an RSA operation to sign the message digest
+ */
+int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx,
+                    int (*f_rng)(void *, unsigned char *, size_t),
+                    void *p_rng,
+                    int mode,
+                    mbedtls_md_type_t md_alg,
+                    unsigned int hashlen,
+                    const unsigned char *hash,
+                    unsigned char *sig )
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+    RSA_VALIDATE_RET( sig != NULL );
+
+    switch( ctx->padding )
+    {
+#if defined(MBEDTLS_PKCS1_V15)
+        case MBEDTLS_RSA_PKCS_V15:
+            return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg,
+                                              hashlen, hash, sig );
+#endif
+
+#if defined(MBEDTLS_PKCS1_V21)
+        case MBEDTLS_RSA_PKCS_V21:
+            return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg,
+                                        hashlen, hash, sig );
+#endif
+
+        default:
+            return( MBEDTLS_ERR_RSA_INVALID_PADDING );
+    }
+}
+
+#if defined(MBEDTLS_PKCS1_V21)
+/*
+ * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function
+ */
+int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
+                               int (*f_rng)(void *, unsigned char *, size_t),
+                               void *p_rng,
+                               int mode,
+                               mbedtls_md_type_t md_alg,
+                               unsigned int hashlen,
+                               const unsigned char *hash,
+                               mbedtls_md_type_t mgf1_hash_id,
+                               int expected_salt_len,
+                               const unsigned char *sig )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t siglen;
+    unsigned char *p;
+    unsigned char *hash_start;
+    unsigned char result[MBEDTLS_MD_MAX_SIZE];
+    unsigned char zeros[8];
+    unsigned int hlen;
+    size_t observed_salt_len, msb;
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+    unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( sig != NULL );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    siglen = ctx->len;
+
+    if( siglen < 16 || siglen > sizeof( buf ) )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    ret = ( mode == MBEDTLS_RSA_PUBLIC )
+          ? mbedtls_rsa_public(  ctx, sig, buf )
+          : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf );
+
+    if( ret != 0 )
+        return( ret );
+
+    p = buf;
+
+    if( buf[siglen - 1] != 0xBC )
+        return( MBEDTLS_ERR_RSA_INVALID_PADDING );
+
+    if( md_alg != MBEDTLS_MD_NONE )
+    {
+        /* Gather length of hash to sign */
+        md_info = mbedtls_md_info_from_type( md_alg );
+        if( md_info == NULL )
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+        hashlen = mbedtls_md_get_size( md_info );
+    }
+
+    md_info = mbedtls_md_info_from_type( mgf1_hash_id );
+    if( md_info == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    hlen = mbedtls_md_get_size( md_info );
+
+    memset( zeros, 0, 8 );
+
+    /*
+     * Note: EMSA-PSS verification is over the length of N - 1 bits
+     */
+    msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
+
+    if( buf[0] >> ( 8 - siglen * 8 + msb ) )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    /* Compensate for boundary condition when applying mask */
+    if( msb % 8 == 0 )
+    {
+        p++;
+        siglen -= 1;
+    }
+
+    if( siglen < hlen + 2 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+    hash_start = p + siglen - hlen - 1;
+
+    mbedtls_md_init( &md_ctx );
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
+        goto exit;
+
+    ret = mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx );
+    if( ret != 0 )
+        goto exit;
+
+    buf[0] &= 0xFF >> ( siglen * 8 - msb );
+
+    while( p < hash_start - 1 && *p == 0 )
+        p++;
+
+    if( *p++ != 0x01 )
+    {
+        ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
+        goto exit;
+    }
+
+    observed_salt_len = hash_start - p;
+
+    if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
+        observed_salt_len != (size_t) expected_salt_len )
+    {
+        ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
+        goto exit;
+    }
+
+    /*
+     * Generate H = Hash( M' )
+     */
+    ret = mbedtls_md_starts( &md_ctx );
+    if ( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_update( &md_ctx, zeros, 8 );
+    if ( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_update( &md_ctx, hash, hashlen );
+    if ( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_update( &md_ctx, p, observed_salt_len );
+    if ( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_finish( &md_ctx, result );
+    if ( ret != 0 )
+        goto exit;
+
+    if( memcmp( hash_start, result, hlen ) != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
+        goto exit;
+    }
+
+exit:
+    mbedtls_md_free( &md_ctx );
+
+    return( ret );
+}
+
+/*
+ * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function
+ */
+int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx,
+                           int (*f_rng)(void *, unsigned char *, size_t),
+                           void *p_rng,
+                           int mode,
+                           mbedtls_md_type_t md_alg,
+                           unsigned int hashlen,
+                           const unsigned char *hash,
+                           const unsigned char *sig )
+{
+    mbedtls_md_type_t mgf1_hash_id;
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( sig != NULL );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+
+    mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE )
+                             ? (mbedtls_md_type_t) ctx->hash_id
+                             : md_alg;
+
+    return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode,
+                                       md_alg, hashlen, hash,
+                                       mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY,
+                                       sig ) );
+
+}
+#endif /* MBEDTLS_PKCS1_V21 */
+
+#if defined(MBEDTLS_PKCS1_V15)
+/*
+ * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function
+ */
+int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
+                                 int (*f_rng)(void *, unsigned char *, size_t),
+                                 void *p_rng,
+                                 int mode,
+                                 mbedtls_md_type_t md_alg,
+                                 unsigned int hashlen,
+                                 const unsigned char *hash,
+                                 const unsigned char *sig )
+{
+    int ret = 0;
+    size_t sig_len;
+    unsigned char *encoded = NULL, *encoded_expected = NULL;
+
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( sig != NULL );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+
+    sig_len = ctx->len;
+
+    if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+    /*
+     * Prepare expected PKCS1 v1.5 encoding of hash.
+     */
+
+    if( ( encoded          = mbedtls_calloc( 1, sig_len ) ) == NULL ||
+        ( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL )
+    {
+        ret = MBEDTLS_ERR_MPI_ALLOC_FAILED;
+        goto cleanup;
+    }
+
+    if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len,
+                                             encoded_expected ) ) != 0 )
+        goto cleanup;
+
+    /*
+     * Apply RSA primitive to get what should be PKCS1 encoded hash.
+     */
+
+    ret = ( mode == MBEDTLS_RSA_PUBLIC )
+          ? mbedtls_rsa_public(  ctx, sig, encoded )
+          : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded );
+    if( ret != 0 )
+        goto cleanup;
+
+    /*
+     * Compare
+     */
+
+    if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected,
+                                      sig_len ) ) != 0 )
+    {
+        ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
+        goto cleanup;
+    }
+
+cleanup:
+
+    if( encoded != NULL )
+    {
+        mbedtls_platform_zeroize( encoded, sig_len );
+        mbedtls_free( encoded );
+    }
+
+    if( encoded_expected != NULL )
+    {
+        mbedtls_platform_zeroize( encoded_expected, sig_len );
+        mbedtls_free( encoded_expected );
+    }
+
+    return( ret );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+/*
+ * Do an RSA operation and check the message digest
+ */
+int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
+                      int (*f_rng)(void *, unsigned char *, size_t),
+                      void *p_rng,
+                      int mode,
+                      mbedtls_md_type_t md_alg,
+                      unsigned int hashlen,
+                      const unsigned char *hash,
+                      const unsigned char *sig )
+{
+    RSA_VALIDATE_RET( ctx != NULL );
+    RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+                      mode == MBEDTLS_RSA_PUBLIC );
+    RSA_VALIDATE_RET( sig != NULL );
+    RSA_VALIDATE_RET( ( md_alg  == MBEDTLS_MD_NONE &&
+                        hashlen == 0 ) ||
+                      hash != NULL );
+
+    switch( ctx->padding )
+    {
+#if defined(MBEDTLS_PKCS1_V15)
+        case MBEDTLS_RSA_PKCS_V15:
+            return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg,
+                                                hashlen, hash, sig );
+#endif
+
+#if defined(MBEDTLS_PKCS1_V21)
+        case MBEDTLS_RSA_PKCS_V21:
+            return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg,
+                                          hashlen, hash, sig );
+#endif
+
+        default:
+            return( MBEDTLS_ERR_RSA_INVALID_PADDING );
+    }
+}
+
+/*
+ * Copy the components of an RSA key
+ */
+int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    RSA_VALIDATE_RET( dst != NULL );
+    RSA_VALIDATE_RET( src != NULL );
+
+    dst->len = src->len;
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) );
+#endif
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) );
+
+    dst->padding = src->padding;
+    dst->hash_id = src->hash_id;
+
+cleanup:
+    if( ret != 0 )
+        mbedtls_rsa_free( dst );
+
+    return( ret );
+}
+
+/*
+ * Free the components of an RSA key
+ */
+void mbedtls_rsa_free( mbedtls_rsa_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_mpi_free( &ctx->Vi );
+    mbedtls_mpi_free( &ctx->Vf );
+    mbedtls_mpi_free( &ctx->RN );
+    mbedtls_mpi_free( &ctx->D  );
+    mbedtls_mpi_free( &ctx->Q  );
+    mbedtls_mpi_free( &ctx->P  );
+    mbedtls_mpi_free( &ctx->E  );
+    mbedtls_mpi_free( &ctx->N  );
+
+#if !defined(MBEDTLS_RSA_NO_CRT)
+    mbedtls_mpi_free( &ctx->RQ );
+    mbedtls_mpi_free( &ctx->RP );
+    mbedtls_mpi_free( &ctx->QP );
+    mbedtls_mpi_free( &ctx->DQ );
+    mbedtls_mpi_free( &ctx->DP );
+#endif /* MBEDTLS_RSA_NO_CRT */
+
+#if defined(MBEDTLS_THREADING_C)
+    /* Free the mutex, but only if it hasn't been freed already. */
+    if( ctx->ver != 0 )
+    {
+        mbedtls_mutex_free( &ctx->mutex );
+        ctx->ver = 0;
+    }
+#endif
+}
+
+#endif /* !MBEDTLS_RSA_ALT */
+
+#if defined(MBEDTLS_SELF_TEST)
+
+#include "mbedtls/sha1.h"
+
+/*
+ * Example RSA-1024 keypair, for test purposes
+ */
+#define KEY_LEN 128
+
+#define RSA_N   "9292758453063D803DD603D5E777D788" \
+                "8ED1D5BF35786190FA2F23EBC0848AEA" \
+                "DDA92CA6C3D80B32C4D109BE0F36D6AE" \
+                "7130B9CED7ACDF54CFC7555AC14EEBAB" \
+                "93A89813FBF3C4F8066D2D800F7C38A8" \
+                "1AE31942917403FF4946B0A83D3D3E05" \
+                "EE57C6F5F5606FB5D4BC6CD34EE0801A" \
+                "5E94BB77B07507233A0BC7BAC8F90F79"
+
+#define RSA_E   "10001"
+
+#define RSA_D   "24BF6185468786FDD303083D25E64EFC" \
+                "66CA472BC44D253102F8B4A9D3BFA750" \
+                "91386C0077937FE33FA3252D28855837" \
+                "AE1B484A8A9A45F7EE8C0C634F99E8CD" \
+                "DF79C5CE07EE72C7F123142198164234" \
+                "CABB724CF78B8173B9F880FC86322407" \
+                "AF1FEDFDDE2BEB674CA15F3E81A1521E" \
+                "071513A1E85B5DFA031F21ECAE91A34D"
+
+#define RSA_P   "C36D0EB7FCD285223CFB5AABA5BDA3D8" \
+                "2C01CAD19EA484A87EA4377637E75500" \
+                "FCB2005C5C7DD6EC4AC023CDA285D796" \
+                "C3D9E75E1EFC42488BB4F1D13AC30A57"
+
+#define RSA_Q   "C000DF51A7C77AE8D7C7370C1FF55B69" \
+                "E211C2B9E5DB1ED0BF61D0D9899620F4" \
+                "910E4168387E3C30AA1E00C339A79508" \
+                "8452DD96A9A5EA5D9DCA68DA636032AF"
+
+#define PT_LEN  24
+#define RSA_PT  "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \
+                "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD"
+
+#if defined(MBEDTLS_PKCS1_V15)
+static int myrand( void *rng_state, unsigned char *output, size_t len )
+{
+#if !defined(__OpenBSD__) && !defined(__NetBSD__)
+    size_t i;
+
+    if( rng_state != NULL )
+        rng_state  = NULL;
+
+    for( i = 0; i < len; ++i )
+        output[i] = rand();
+#else
+    if( rng_state != NULL )
+        rng_state = NULL;
+
+    arc4random_buf( output, len );
+#endif /* !OpenBSD && !NetBSD */
+
+    return( 0 );
+}
+#endif /* MBEDTLS_PKCS1_V15 */
+
+/*
+ * Checkup routine
+ */
+int mbedtls_rsa_self_test( int verbose )
+{
+    int ret = 0;
+#if defined(MBEDTLS_PKCS1_V15)
+    size_t len;
+    mbedtls_rsa_context rsa;
+    unsigned char rsa_plaintext[PT_LEN];
+    unsigned char rsa_decrypted[PT_LEN];
+    unsigned char rsa_ciphertext[KEY_LEN];
+#if defined(MBEDTLS_SHA1_C)
+    unsigned char sha1sum[20];
+#endif
+
+    mbedtls_mpi K;
+
+    mbedtls_mpi_init( &K );
+    mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_N  ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, &K, NULL, NULL, NULL, NULL ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_P  ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, &K, NULL, NULL, NULL ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_Q  ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, &K, NULL, NULL ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_D  ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, &K, NULL ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_E  ) );
+    MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, NULL, &K ) );
+
+    MBEDTLS_MPI_CHK( mbedtls_rsa_complete( &rsa ) );
+
+    if( verbose != 0 )
+        mbedtls_printf( "  RSA key validation: " );
+
+    if( mbedtls_rsa_check_pubkey(  &rsa ) != 0 ||
+        mbedtls_rsa_check_privkey( &rsa ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n  PKCS#1 encryption : " );
+
+    memcpy( rsa_plaintext, RSA_PT, PT_LEN );
+
+    if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC,
+                                   PT_LEN, rsa_plaintext,
+                                   rsa_ciphertext ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n  PKCS#1 decryption : " );
+
+    if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE,
+                                   &len, rsa_ciphertext, rsa_decrypted,
+                                   sizeof(rsa_decrypted) ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n" );
+
+#if defined(MBEDTLS_SHA1_C)
+    if( verbose != 0 )
+        mbedtls_printf( "  PKCS#1 data sign  : " );
+
+    if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        return( 1 );
+    }
+
+    if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL,
+                                MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0,
+                                sha1sum, rsa_ciphertext ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n  PKCS#1 sig. verify: " );
+
+    if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL,
+                                  MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0,
+                                  sha1sum, rsa_ciphertext ) != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n" );
+#endif /* MBEDTLS_SHA1_C */
+
+    if( verbose != 0 )
+        mbedtls_printf( "\n" );
+
+cleanup:
+    mbedtls_mpi_free( &K );
+    mbedtls_rsa_free( &rsa );
+#else /* MBEDTLS_PKCS1_V15 */
+    ((void) verbose);
+#endif /* MBEDTLS_PKCS1_V15 */
+    return( ret );
+}
+
+#endif /* MBEDTLS_SELF_TEST */
+
+#endif /* MBEDTLS_RSA_C */