diff options
Diffstat (limited to 'lib/mbedtls-2.27.0/library/ecdsa.c')
| -rw-r--r-- | lib/mbedtls-2.27.0/library/ecdsa.c | 1012 |
1 files changed, 1012 insertions, 0 deletions
diff --git a/lib/mbedtls-2.27.0/library/ecdsa.c b/lib/mbedtls-2.27.0/library/ecdsa.c new file mode 100644 index 0000000..640eb24 --- /dev/null +++ b/lib/mbedtls-2.27.0/library/ecdsa.c @@ -0,0 +1,1012 @@ +/* + * Elliptic curve DSA + * + * 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. + */ + +/* + * References: + * + * SEC1 http://www.secg.org/index.php?action=secg,docs_secg + */ + +#include "common.h" + +#if defined(MBEDTLS_ECDSA_C) + +#include "mbedtls/ecdsa.h" +#include "mbedtls/asn1write.h" + +#include <string.h> + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) +#include "mbedtls/hmac_drbg.h" +#endif + +#if defined(MBEDTLS_PLATFORM_C) +#include "mbedtls/platform.h" +#else +#include <stdlib.h> +#define mbedtls_calloc calloc +#define mbedtls_free free +#endif + +#include "mbedtls/platform_util.h" +#include "mbedtls/error.h" + +/* Parameter validation macros based on platform_util.h */ +#define ECDSA_VALIDATE_RET( cond ) \ + MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA ) +#define ECDSA_VALIDATE( cond ) \ + MBEDTLS_INTERNAL_VALIDATE( cond ) + +#if defined(MBEDTLS_ECP_RESTARTABLE) + +/* + * Sub-context for ecdsa_verify() + */ +struct mbedtls_ecdsa_restart_ver +{ + mbedtls_mpi u1, u2; /* intermediate values */ + enum { /* what to do next? */ + ecdsa_ver_init = 0, /* getting started */ + ecdsa_ver_muladd, /* muladd step */ + } state; +}; + +/* + * Init verify restart sub-context + */ +static void ecdsa_restart_ver_init( mbedtls_ecdsa_restart_ver_ctx *ctx ) +{ + mbedtls_mpi_init( &ctx->u1 ); + mbedtls_mpi_init( &ctx->u2 ); + ctx->state = ecdsa_ver_init; +} + +/* + * Free the components of a verify restart sub-context + */ +static void ecdsa_restart_ver_free( mbedtls_ecdsa_restart_ver_ctx *ctx ) +{ + if( ctx == NULL ) + return; + + mbedtls_mpi_free( &ctx->u1 ); + mbedtls_mpi_free( &ctx->u2 ); + + ecdsa_restart_ver_init( ctx ); +} + +/* + * Sub-context for ecdsa_sign() + */ +struct mbedtls_ecdsa_restart_sig +{ + int sign_tries; + int key_tries; + mbedtls_mpi k; /* per-signature random */ + mbedtls_mpi r; /* r value */ + enum { /* what to do next? */ + ecdsa_sig_init = 0, /* getting started */ + ecdsa_sig_mul, /* doing ecp_mul() */ + ecdsa_sig_modn, /* mod N computations */ + } state; +}; + +/* + * Init verify sign sub-context + */ +static void ecdsa_restart_sig_init( mbedtls_ecdsa_restart_sig_ctx *ctx ) +{ + ctx->sign_tries = 0; + ctx->key_tries = 0; + mbedtls_mpi_init( &ctx->k ); + mbedtls_mpi_init( &ctx->r ); + ctx->state = ecdsa_sig_init; +} + +/* + * Free the components of a sign restart sub-context + */ +static void ecdsa_restart_sig_free( mbedtls_ecdsa_restart_sig_ctx *ctx ) +{ + if( ctx == NULL ) + return; + + mbedtls_mpi_free( &ctx->k ); + mbedtls_mpi_free( &ctx->r ); +} + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) +/* + * Sub-context for ecdsa_sign_det() + */ +struct mbedtls_ecdsa_restart_det +{ + mbedtls_hmac_drbg_context rng_ctx; /* DRBG state */ + enum { /* what to do next? */ + ecdsa_det_init = 0, /* getting started */ + ecdsa_det_sign, /* make signature */ + } state; +}; + +/* + * Init verify sign_det sub-context + */ +static void ecdsa_restart_det_init( mbedtls_ecdsa_restart_det_ctx *ctx ) +{ + mbedtls_hmac_drbg_init( &ctx->rng_ctx ); + ctx->state = ecdsa_det_init; +} + +/* + * Free the components of a sign_det restart sub-context + */ +static void ecdsa_restart_det_free( mbedtls_ecdsa_restart_det_ctx *ctx ) +{ + if( ctx == NULL ) + return; + + mbedtls_hmac_drbg_free( &ctx->rng_ctx ); + + ecdsa_restart_det_init( ctx ); +} +#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ + +#define ECDSA_RS_ECP ( rs_ctx == NULL ? NULL : &rs_ctx->ecp ) + +/* Utility macro for checking and updating ops budget */ +#define ECDSA_BUDGET( ops ) \ + MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, ECDSA_RS_ECP, ops ) ); + +/* Call this when entering a function that needs its own sub-context */ +#define ECDSA_RS_ENTER( SUB ) do { \ + /* reset ops count for this call if top-level */ \ + if( rs_ctx != NULL && rs_ctx->ecp.depth++ == 0 ) \ + rs_ctx->ecp.ops_done = 0; \ + \ + /* set up our own sub-context if needed */ \ + if( mbedtls_ecp_restart_is_enabled() && \ + rs_ctx != NULL && rs_ctx->SUB == NULL ) \ + { \ + rs_ctx->SUB = mbedtls_calloc( 1, sizeof( *rs_ctx->SUB ) ); \ + if( rs_ctx->SUB == NULL ) \ + return( MBEDTLS_ERR_ECP_ALLOC_FAILED ); \ + \ + ecdsa_restart_## SUB ##_init( rs_ctx->SUB ); \ + } \ +} while( 0 ) + +/* Call this when leaving a function that needs its own sub-context */ +#define ECDSA_RS_LEAVE( SUB ) do { \ + /* clear our sub-context when not in progress (done or error) */ \ + if( rs_ctx != NULL && rs_ctx->SUB != NULL && \ + ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) \ + { \ + ecdsa_restart_## SUB ##_free( rs_ctx->SUB ); \ + mbedtls_free( rs_ctx->SUB ); \ + rs_ctx->SUB = NULL; \ + } \ + \ + if( rs_ctx != NULL ) \ + rs_ctx->ecp.depth--; \ +} while( 0 ) + +#else /* MBEDTLS_ECP_RESTARTABLE */ + +#define ECDSA_RS_ECP NULL + +#define ECDSA_BUDGET( ops ) /* no-op; for compatibility */ + +#define ECDSA_RS_ENTER( SUB ) (void) rs_ctx +#define ECDSA_RS_LEAVE( SUB ) (void) rs_ctx + +#endif /* MBEDTLS_ECP_RESTARTABLE */ + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) || \ + !defined(MBEDTLS_ECDSA_SIGN_ALT) || \ + !defined(MBEDTLS_ECDSA_VERIFY_ALT) +/* + * Derive a suitable integer for group grp from a buffer of length len + * SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3 + */ +static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x, + const unsigned char *buf, size_t blen ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t n_size = ( grp->nbits + 7 ) / 8; + size_t use_size = blen > n_size ? n_size : blen; + + MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) ); + if( use_size * 8 > grp->nbits ) + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) ); + + /* While at it, reduce modulo N */ + if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 ) + MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) ); + +cleanup: + return( ret ); +} +#endif /* ECDSA_DETERMINISTIC || !ECDSA_SIGN_ALT || !ECDSA_VERIFY_ALT */ + +#if !defined(MBEDTLS_ECDSA_SIGN_ALT) +/* + * Compute ECDSA signature of a hashed message (SEC1 4.1.3) + * Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message) + */ +static int ecdsa_sign_restartable( mbedtls_ecp_group *grp, + mbedtls_mpi *r, mbedtls_mpi *s, + const mbedtls_mpi *d, const unsigned char *buf, size_t blen, + int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, + int (*f_rng_blind)(void *, unsigned char *, size_t), + void *p_rng_blind, + mbedtls_ecdsa_restart_ctx *rs_ctx ) +{ + int ret, key_tries, sign_tries; + int *p_sign_tries = &sign_tries, *p_key_tries = &key_tries; + mbedtls_ecp_point R; + mbedtls_mpi k, e, t; + mbedtls_mpi *pk = &k, *pr = r; + + /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */ + if( ! mbedtls_ecdsa_can_do( grp->id ) || grp->N.p == NULL ) + return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); + + /* Make sure d is in range 1..n-1 */ + if( mbedtls_mpi_cmp_int( d, 1 ) < 0 || mbedtls_mpi_cmp_mpi( d, &grp->N ) >= 0 ) + return( MBEDTLS_ERR_ECP_INVALID_KEY ); + + mbedtls_ecp_point_init( &R ); + mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t ); + + ECDSA_RS_ENTER( sig ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->sig != NULL ) + { + /* redirect to our context */ + p_sign_tries = &rs_ctx->sig->sign_tries; + p_key_tries = &rs_ctx->sig->key_tries; + pk = &rs_ctx->sig->k; + pr = &rs_ctx->sig->r; + + /* jump to current step */ + if( rs_ctx->sig->state == ecdsa_sig_mul ) + goto mul; + if( rs_ctx->sig->state == ecdsa_sig_modn ) + goto modn; + } +#endif /* MBEDTLS_ECP_RESTARTABLE */ + + *p_sign_tries = 0; + do + { + if( (*p_sign_tries)++ > 10 ) + { + ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; + goto cleanup; + } + + /* + * Steps 1-3: generate a suitable ephemeral keypair + * and set r = xR mod n + */ + *p_key_tries = 0; + do + { + if( (*p_key_tries)++ > 10 ) + { + ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; + goto cleanup; + } + + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, pk, f_rng, p_rng ) ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->sig != NULL ) + rs_ctx->sig->state = ecdsa_sig_mul; + +mul: +#endif + MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &R, pk, &grp->G, + f_rng_blind, + p_rng_blind, + ECDSA_RS_ECP ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pr, &R.X, &grp->N ) ); + } + while( mbedtls_mpi_cmp_int( pr, 0 ) == 0 ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->sig != NULL ) + rs_ctx->sig->state = ecdsa_sig_modn; + +modn: +#endif + /* + * Accounting for everything up to the end of the loop + * (step 6, but checking now avoids saving e and t) + */ + ECDSA_BUDGET( MBEDTLS_ECP_OPS_INV + 4 ); + + /* + * Step 5: derive MPI from hashed message + */ + MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) ); + + /* + * Generate a random value to blind inv_mod in next step, + * avoiding a potential timing leak. + */ + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, &t, f_rng_blind, + p_rng_blind ) ); + + /* + * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n + */ + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, pr, d ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pk, pk, &t ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pk, pk, &grp->N ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, pk, &grp->N ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) ); + } + while( mbedtls_mpi_cmp_int( s, 0 ) == 0 ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->sig != NULL ) + mbedtls_mpi_copy( r, pr ); +#endif + +cleanup: + mbedtls_ecp_point_free( &R ); + mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t ); + + ECDSA_RS_LEAVE( sig ); + + return( ret ); +} + +int mbedtls_ecdsa_can_do( mbedtls_ecp_group_id gid ) +{ + switch( gid ) + { +#ifdef MBEDTLS_ECP_DP_CURVE25519_ENABLED + case MBEDTLS_ECP_DP_CURVE25519: return 0; +#endif +#ifdef MBEDTLS_ECP_DP_CURVE448_ENABLED + case MBEDTLS_ECP_DP_CURVE448: return 0; +#endif + default: return 1; + } +} + +/* + * Compute ECDSA signature of a hashed message + */ +int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s, + const mbedtls_mpi *d, const unsigned char *buf, size_t blen, + int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) +{ + ECDSA_VALIDATE_RET( grp != NULL ); + ECDSA_VALIDATE_RET( r != NULL ); + ECDSA_VALIDATE_RET( s != NULL ); + ECDSA_VALIDATE_RET( d != NULL ); + ECDSA_VALIDATE_RET( f_rng != NULL ); + ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); + + /* Use the same RNG for both blinding and ephemeral key generation */ + return( ecdsa_sign_restartable( grp, r, s, d, buf, blen, + f_rng, p_rng, f_rng, p_rng, NULL ) ); +} +#endif /* !MBEDTLS_ECDSA_SIGN_ALT */ + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) +/* + * Deterministic signature wrapper + */ +static int ecdsa_sign_det_restartable( mbedtls_ecp_group *grp, + mbedtls_mpi *r, mbedtls_mpi *s, + const mbedtls_mpi *d, const unsigned char *buf, size_t blen, + mbedtls_md_type_t md_alg, + int (*f_rng_blind)(void *, unsigned char *, size_t), + void *p_rng_blind, + mbedtls_ecdsa_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_hmac_drbg_context rng_ctx; + mbedtls_hmac_drbg_context *p_rng = &rng_ctx; + unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES]; + size_t grp_len = ( grp->nbits + 7 ) / 8; + const mbedtls_md_info_t *md_info; + mbedtls_mpi h; + + if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL ) + return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); + + mbedtls_mpi_init( &h ); + mbedtls_hmac_drbg_init( &rng_ctx ); + + ECDSA_RS_ENTER( det ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->det != NULL ) + { + /* redirect to our context */ + p_rng = &rs_ctx->det->rng_ctx; + + /* jump to current step */ + if( rs_ctx->det->state == ecdsa_det_sign ) + goto sign; + } +#endif /* MBEDTLS_ECP_RESTARTABLE */ + + /* Use private key and message hash (reduced) to initialize HMAC_DRBG */ + MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) ); + MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) ); + mbedtls_hmac_drbg_seed_buf( p_rng, md_info, data, 2 * grp_len ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->det != NULL ) + rs_ctx->det->state = ecdsa_det_sign; + +sign: +#endif +#if defined(MBEDTLS_ECDSA_SIGN_ALT) + (void) f_rng_blind; + (void) p_rng_blind; + ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen, + mbedtls_hmac_drbg_random, p_rng ); +#else + if( f_rng_blind != NULL ) + ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen, + mbedtls_hmac_drbg_random, p_rng, + f_rng_blind, p_rng_blind, rs_ctx ); + else + { + mbedtls_hmac_drbg_context *p_rng_blind_det; + +#if !defined(MBEDTLS_ECP_RESTARTABLE) + /* + * To avoid reusing rng_ctx and risking incorrect behavior we seed a + * second HMAC-DRBG with the same seed. We also apply a label to avoid + * reusing the bits of the ephemeral key for blinding and eliminate the + * risk that they leak this way. + */ + const char* blind_label = "BLINDING CONTEXT"; + mbedtls_hmac_drbg_context rng_ctx_blind; + + mbedtls_hmac_drbg_init( &rng_ctx_blind ); + p_rng_blind_det = &rng_ctx_blind; + mbedtls_hmac_drbg_seed_buf( p_rng_blind_det, md_info, + data, 2 * grp_len ); + ret = mbedtls_hmac_drbg_update_ret( p_rng_blind_det, + (const unsigned char*) blind_label, + strlen( blind_label ) ); + if( ret != 0 ) + { + mbedtls_hmac_drbg_free( &rng_ctx_blind ); + goto cleanup; + } +#else + /* + * In the case of restartable computations we would either need to store + * the second RNG in the restart context too or set it up at every + * restart. The first option would penalize the correct application of + * the function and the second would defeat the purpose of the + * restartable feature. + * + * Therefore in this case we reuse the original RNG. This comes with the + * price that the resulting signature might not be a valid deterministic + * ECDSA signature with a very low probability (same magnitude as + * successfully guessing the private key). However even then it is still + * a valid ECDSA signature. + */ + p_rng_blind_det = p_rng; +#endif /* MBEDTLS_ECP_RESTARTABLE */ + + /* + * Since the output of the RNGs is always the same for the same key and + * message, this limits the efficiency of blinding and leaks information + * through side channels. After mbedtls_ecdsa_sign_det() is removed NULL + * won't be a valid value for f_rng_blind anymore. Therefore it should + * be checked by the caller and this branch and check can be removed. + */ + ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen, + mbedtls_hmac_drbg_random, p_rng, + mbedtls_hmac_drbg_random, p_rng_blind_det, + rs_ctx ); + +#if !defined(MBEDTLS_ECP_RESTARTABLE) + mbedtls_hmac_drbg_free( &rng_ctx_blind ); +#endif + } +#endif /* MBEDTLS_ECDSA_SIGN_ALT */ + +cleanup: + mbedtls_hmac_drbg_free( &rng_ctx ); + mbedtls_mpi_free( &h ); + + ECDSA_RS_LEAVE( det ); + + return( ret ); +} + +/* + * Deterministic signature wrappers + */ + +#if !defined(MBEDTLS_DEPRECATED_REMOVED) +int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, + mbedtls_mpi *s, const mbedtls_mpi *d, + const unsigned char *buf, size_t blen, + mbedtls_md_type_t md_alg ) +{ + ECDSA_VALIDATE_RET( grp != NULL ); + ECDSA_VALIDATE_RET( r != NULL ); + ECDSA_VALIDATE_RET( s != NULL ); + ECDSA_VALIDATE_RET( d != NULL ); + ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); + + return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg, + NULL, NULL, NULL ) ); +} +#endif /* MBEDTLS_DEPRECATED_REMOVED */ + +int mbedtls_ecdsa_sign_det_ext( mbedtls_ecp_group *grp, mbedtls_mpi *r, + mbedtls_mpi *s, const mbedtls_mpi *d, + const unsigned char *buf, size_t blen, + mbedtls_md_type_t md_alg, + int (*f_rng_blind)(void *, unsigned char *, + size_t), + void *p_rng_blind ) +{ + ECDSA_VALIDATE_RET( grp != NULL ); + ECDSA_VALIDATE_RET( r != NULL ); + ECDSA_VALIDATE_RET( s != NULL ); + ECDSA_VALIDATE_RET( d != NULL ); + ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); + ECDSA_VALIDATE_RET( f_rng_blind != NULL ); + + return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg, + f_rng_blind, p_rng_blind, NULL ) ); +} +#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ + +#if !defined(MBEDTLS_ECDSA_VERIFY_ALT) +/* + * Verify ECDSA signature of hashed message (SEC1 4.1.4) + * Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message) + */ +static int ecdsa_verify_restartable( mbedtls_ecp_group *grp, + const unsigned char *buf, size_t blen, + const mbedtls_ecp_point *Q, + const mbedtls_mpi *r, const mbedtls_mpi *s, + mbedtls_ecdsa_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi e, s_inv, u1, u2; + mbedtls_ecp_point R; + mbedtls_mpi *pu1 = &u1, *pu2 = &u2; + + mbedtls_ecp_point_init( &R ); + mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); + mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 ); + + /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */ + if( ! mbedtls_ecdsa_can_do( grp->id ) || grp->N.p == NULL ) + return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); + + ECDSA_RS_ENTER( ver ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->ver != NULL ) + { + /* redirect to our context */ + pu1 = &rs_ctx->ver->u1; + pu2 = &rs_ctx->ver->u2; + + /* jump to current step */ + if( rs_ctx->ver->state == ecdsa_ver_muladd ) + goto muladd; + } +#endif /* MBEDTLS_ECP_RESTARTABLE */ + + /* + * Step 1: make sure r and s are in range 1..n-1 + */ + if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 || + mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 ) + { + ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; + goto cleanup; + } + + /* + * Step 3: derive MPI from hashed message + */ + MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) ); + + /* + * Step 4: u1 = e / s mod n, u2 = r / s mod n + */ + ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 ); + + MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) ); + + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu1, &e, &s_inv ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu1, pu1, &grp->N ) ); + + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu2, r, &s_inv ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu2, pu2, &grp->N ) ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx != NULL && rs_ctx->ver != NULL ) + rs_ctx->ver->state = ecdsa_ver_muladd; + +muladd: +#endif + /* + * Step 5: R = u1 G + u2 Q + */ + MBEDTLS_MPI_CHK( mbedtls_ecp_muladd_restartable( grp, + &R, pu1, &grp->G, pu2, Q, ECDSA_RS_ECP ) ); + + if( mbedtls_ecp_is_zero( &R ) ) + { + ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; + goto cleanup; + } + + /* + * Step 6: convert xR to an integer (no-op) + * Step 7: reduce xR mod n (gives v) + */ + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) ); + + /* + * Step 8: check if v (that is, R.X) is equal to r + */ + if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 ) + { + ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; + goto cleanup; + } + +cleanup: + mbedtls_ecp_point_free( &R ); + mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); + mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 ); + + ECDSA_RS_LEAVE( ver ); + + return( ret ); +} + +/* + * Verify ECDSA signature of hashed message + */ +int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp, + const unsigned char *buf, size_t blen, + const mbedtls_ecp_point *Q, + const mbedtls_mpi *r, + const mbedtls_mpi *s) +{ + ECDSA_VALIDATE_RET( grp != NULL ); + ECDSA_VALIDATE_RET( Q != NULL ); + ECDSA_VALIDATE_RET( r != NULL ); + ECDSA_VALIDATE_RET( s != NULL ); + ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); + + return( ecdsa_verify_restartable( grp, buf, blen, Q, r, s, NULL ) ); +} +#endif /* !MBEDTLS_ECDSA_VERIFY_ALT */ + +/* + * Convert a signature (given by context) to ASN.1 + */ +static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s, + unsigned char *sig, size_t *slen ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char buf[MBEDTLS_ECDSA_MAX_LEN] = {0}; + unsigned char *p = buf + sizeof( buf ); + size_t len = 0; + + MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) ); + MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) ); + + MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) ); + MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf, + MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); + + memcpy( sig, p, len ); + *slen = len; + + return( 0 ); +} + +/* + * Compute and write signature + */ +int mbedtls_ecdsa_write_signature_restartable( mbedtls_ecdsa_context *ctx, + mbedtls_md_type_t md_alg, + const unsigned char *hash, size_t hlen, + unsigned char *sig, size_t *slen, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng, + mbedtls_ecdsa_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi r, s; + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( hash != NULL ); + ECDSA_VALIDATE_RET( sig != NULL ); + ECDSA_VALIDATE_RET( slen != NULL ); + + mbedtls_mpi_init( &r ); + mbedtls_mpi_init( &s ); + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) + MBEDTLS_MPI_CHK( ecdsa_sign_det_restartable( &ctx->grp, &r, &s, &ctx->d, + hash, hlen, md_alg, f_rng, + p_rng, rs_ctx ) ); +#else + (void) md_alg; + +#if defined(MBEDTLS_ECDSA_SIGN_ALT) + (void) rs_ctx; + + MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d, + hash, hlen, f_rng, p_rng ) ); +#else + /* Use the same RNG for both blinding and ephemeral key generation */ + MBEDTLS_MPI_CHK( ecdsa_sign_restartable( &ctx->grp, &r, &s, &ctx->d, + hash, hlen, f_rng, p_rng, f_rng, + p_rng, rs_ctx ) ); +#endif /* MBEDTLS_ECDSA_SIGN_ALT */ +#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ + + MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) ); + +cleanup: + mbedtls_mpi_free( &r ); + mbedtls_mpi_free( &s ); + + return( ret ); +} + +/* + * Compute and write signature + */ +int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, + mbedtls_md_type_t md_alg, + const unsigned char *hash, size_t hlen, + unsigned char *sig, size_t *slen, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng ) +{ + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( hash != NULL ); + ECDSA_VALIDATE_RET( sig != NULL ); + ECDSA_VALIDATE_RET( slen != NULL ); + return( mbedtls_ecdsa_write_signature_restartable( + ctx, md_alg, hash, hlen, sig, slen, f_rng, p_rng, NULL ) ); +} + +#if !defined(MBEDTLS_DEPRECATED_REMOVED) && \ + defined(MBEDTLS_ECDSA_DETERMINISTIC) +int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx, + const unsigned char *hash, size_t hlen, + unsigned char *sig, size_t *slen, + mbedtls_md_type_t md_alg ) +{ + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( hash != NULL ); + ECDSA_VALIDATE_RET( sig != NULL ); + ECDSA_VALIDATE_RET( slen != NULL ); + return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen, + NULL, NULL ) ); +} +#endif + +/* + * Read and check signature + */ +int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx, + const unsigned char *hash, size_t hlen, + const unsigned char *sig, size_t slen ) +{ + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( hash != NULL ); + ECDSA_VALIDATE_RET( sig != NULL ); + return( mbedtls_ecdsa_read_signature_restartable( + ctx, hash, hlen, sig, slen, NULL ) ); +} + +/* + * Restartable read and check signature + */ +int mbedtls_ecdsa_read_signature_restartable( mbedtls_ecdsa_context *ctx, + const unsigned char *hash, size_t hlen, + const unsigned char *sig, size_t slen, + mbedtls_ecdsa_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = (unsigned char *) sig; + const unsigned char *end = sig + slen; + size_t len; + mbedtls_mpi r, s; + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( hash != NULL ); + ECDSA_VALIDATE_RET( sig != NULL ); + + mbedtls_mpi_init( &r ); + mbedtls_mpi_init( &s ); + + if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, + MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) + { + ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA; + goto cleanup; + } + + if( p + len != end ) + { + ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_ECP_BAD_INPUT_DATA, + MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ); + goto cleanup; + } + + if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 || + ( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 ) + { + ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA; + goto cleanup; + } +#if defined(MBEDTLS_ECDSA_VERIFY_ALT) + (void) rs_ctx; + + if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen, + &ctx->Q, &r, &s ) ) != 0 ) + goto cleanup; +#else + if( ( ret = ecdsa_verify_restartable( &ctx->grp, hash, hlen, + &ctx->Q, &r, &s, rs_ctx ) ) != 0 ) + goto cleanup; +#endif /* MBEDTLS_ECDSA_VERIFY_ALT */ + + /* At this point we know that the buffer starts with a valid signature. + * Return 0 if the buffer just contains the signature, and a specific + * error code if the valid signature is followed by more data. */ + if( p != end ) + ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH; + +cleanup: + mbedtls_mpi_free( &r ); + mbedtls_mpi_free( &s ); + + return( ret ); +} + +#if !defined(MBEDTLS_ECDSA_GENKEY_ALT) +/* + * Generate key pair + */ +int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid, + int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) +{ + int ret = 0; + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( f_rng != NULL ); + + ret = mbedtls_ecp_group_load( &ctx->grp, gid ); + if( ret != 0 ) + return( ret ); + + return( mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, + &ctx->Q, f_rng, p_rng ) ); +} +#endif /* !MBEDTLS_ECDSA_GENKEY_ALT */ + +/* + * Set context from an mbedtls_ecp_keypair + */ +int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + ECDSA_VALIDATE_RET( ctx != NULL ); + ECDSA_VALIDATE_RET( key != NULL ); + + if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 || + ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 || + ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ) + { + mbedtls_ecdsa_free( ctx ); + } + + return( ret ); +} + +/* + * Initialize context + */ +void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx ) +{ + ECDSA_VALIDATE( ctx != NULL ); + + mbedtls_ecp_keypair_init( ctx ); +} + +/* + * Free context + */ +void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx ) +{ + if( ctx == NULL ) + return; + + mbedtls_ecp_keypair_free( ctx ); +} + +#if defined(MBEDTLS_ECP_RESTARTABLE) +/* + * Initialize a restart context + */ +void mbedtls_ecdsa_restart_init( mbedtls_ecdsa_restart_ctx *ctx ) +{ + ECDSA_VALIDATE( ctx != NULL ); + + mbedtls_ecp_restart_init( &ctx->ecp ); + + ctx->ver = NULL; + ctx->sig = NULL; +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) + ctx->det = NULL; +#endif +} + +/* + * Free the components of a restart context + */ +void mbedtls_ecdsa_restart_free( mbedtls_ecdsa_restart_ctx *ctx ) +{ + if( ctx == NULL ) + return; + + mbedtls_ecp_restart_free( &ctx->ecp ); + + ecdsa_restart_ver_free( ctx->ver ); + mbedtls_free( ctx->ver ); + ctx->ver = NULL; + + ecdsa_restart_sig_free( ctx->sig ); + mbedtls_free( ctx->sig ); + ctx->sig = NULL; + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) + ecdsa_restart_det_free( ctx->det ); + mbedtls_free( ctx->det ); + ctx->det = NULL; +#endif +} +#endif /* MBEDTLS_ECP_RESTARTABLE */ + +#endif /* MBEDTLS_ECDSA_C */ |