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+/**
+ * \file bignum.h
+ *
+ * \brief Multi-precision integer library
+ */
+/*
+ * 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.
+ */
+#ifndef MBEDTLS_BIGNUM_H
+#define MBEDTLS_BIGNUM_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(MBEDTLS_FS_IO)
+#include <stdio.h>
+#endif
+
+#define MBEDTLS_ERR_MPI_FILE_IO_ERROR -0x0002 /**< An error occurred while reading from or writing to a file. */
+#define MBEDTLS_ERR_MPI_BAD_INPUT_DATA -0x0004 /**< Bad input parameters to function. */
+#define MBEDTLS_ERR_MPI_INVALID_CHARACTER -0x0006 /**< There is an invalid character in the digit string. */
+#define MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL -0x0008 /**< The buffer is too small to write to. */
+#define MBEDTLS_ERR_MPI_NEGATIVE_VALUE -0x000A /**< The input arguments are negative or result in illegal output. */
+#define MBEDTLS_ERR_MPI_DIVISION_BY_ZERO -0x000C /**< The input argument for division is zero, which is not allowed. */
+#define MBEDTLS_ERR_MPI_NOT_ACCEPTABLE -0x000E /**< The input arguments are not acceptable. */
+#define MBEDTLS_ERR_MPI_ALLOC_FAILED -0x0010 /**< Memory allocation failed. */
+
+#define MBEDTLS_MPI_CHK(f) \
+ do \
+ { \
+ if( ( ret = (f) ) != 0 ) \
+ goto cleanup; \
+ } while( 0 )
+
+/*
+ * Maximum size MPIs are allowed to grow to in number of limbs.
+ */
+#define MBEDTLS_MPI_MAX_LIMBS 10000
+
+#if !defined(MBEDTLS_MPI_WINDOW_SIZE)
+/*
+ * Maximum window size used for modular exponentiation. Default: 6
+ * Minimum value: 1. Maximum value: 6.
+ *
+ * Result is an array of ( 2 ** MBEDTLS_MPI_WINDOW_SIZE ) MPIs used
+ * for the sliding window calculation. (So 64 by default)
+ *
+ * Reduction in size, reduces speed.
+ */
+#define MBEDTLS_MPI_WINDOW_SIZE 6 /**< Maximum window size used. */
+#endif /* !MBEDTLS_MPI_WINDOW_SIZE */
+
+#if !defined(MBEDTLS_MPI_MAX_SIZE)
+/*
+ * Maximum size of MPIs allowed in bits and bytes for user-MPIs.
+ * ( Default: 512 bytes => 4096 bits, Maximum tested: 2048 bytes => 16384 bits )
+ *
+ * Note: Calculations can temporarily result in larger MPIs. So the number
+ * of limbs required (MBEDTLS_MPI_MAX_LIMBS) is higher.
+ */
+#define MBEDTLS_MPI_MAX_SIZE 1024 /**< Maximum number of bytes for usable MPIs. */
+#endif /* !MBEDTLS_MPI_MAX_SIZE */
+
+#define MBEDTLS_MPI_MAX_BITS ( 8 * MBEDTLS_MPI_MAX_SIZE ) /**< Maximum number of bits for usable MPIs. */
+
+/*
+ * When reading from files with mbedtls_mpi_read_file() and writing to files with
+ * mbedtls_mpi_write_file() the buffer should have space
+ * for a (short) label, the MPI (in the provided radix), the newline
+ * characters and the '\0'.
+ *
+ * By default we assume at least a 10 char label, a minimum radix of 10
+ * (decimal) and a maximum of 4096 bit numbers (1234 decimal chars).
+ * Autosized at compile time for at least a 10 char label, a minimum radix
+ * of 10 (decimal) for a number of MBEDTLS_MPI_MAX_BITS size.
+ *
+ * This used to be statically sized to 1250 for a maximum of 4096 bit
+ * numbers (1234 decimal chars).
+ *
+ * Calculate using the formula:
+ * MBEDTLS_MPI_RW_BUFFER_SIZE = ceil(MBEDTLS_MPI_MAX_BITS / ln(10) * ln(2)) +
+ * LabelSize + 6
+ */
+#define MBEDTLS_MPI_MAX_BITS_SCALE100 ( 100 * MBEDTLS_MPI_MAX_BITS )
+#define MBEDTLS_LN_2_DIV_LN_10_SCALE100 332
+#define MBEDTLS_MPI_RW_BUFFER_SIZE ( ((MBEDTLS_MPI_MAX_BITS_SCALE100 + MBEDTLS_LN_2_DIV_LN_10_SCALE100 - 1) / MBEDTLS_LN_2_DIV_LN_10_SCALE100) + 10 + 6 )
+
+/*
+ * Define the base integer type, architecture-wise.
+ *
+ * 32 or 64-bit integer types can be forced regardless of the underlying
+ * architecture by defining MBEDTLS_HAVE_INT32 or MBEDTLS_HAVE_INT64
+ * respectively and undefining MBEDTLS_HAVE_ASM.
+ *
+ * Double-width integers (e.g. 128-bit in 64-bit architectures) can be
+ * disabled by defining MBEDTLS_NO_UDBL_DIVISION.
+ */
+#if !defined(MBEDTLS_HAVE_INT32)
+ #if defined(_MSC_VER) && defined(_M_AMD64)
+ /* Always choose 64-bit when using MSC */
+ #if !defined(MBEDTLS_HAVE_INT64)
+ #define MBEDTLS_HAVE_INT64
+ #endif /* !MBEDTLS_HAVE_INT64 */
+ typedef int64_t mbedtls_mpi_sint;
+ typedef uint64_t mbedtls_mpi_uint;
+ #elif defined(__GNUC__) && ( \
+ defined(__amd64__) || defined(__x86_64__) || \
+ defined(__ppc64__) || defined(__powerpc64__) || \
+ defined(__ia64__) || defined(__alpha__) || \
+ ( defined(__sparc__) && defined(__arch64__) ) || \
+ defined(__s390x__) || defined(__mips64) || \
+ defined(__aarch64__) )
+ #if !defined(MBEDTLS_HAVE_INT64)
+ #define MBEDTLS_HAVE_INT64
+ #endif /* MBEDTLS_HAVE_INT64 */
+ typedef int64_t mbedtls_mpi_sint;
+ typedef uint64_t mbedtls_mpi_uint;
+ #if !defined(MBEDTLS_NO_UDBL_DIVISION)
+ /* mbedtls_t_udbl defined as 128-bit unsigned int */
+ typedef unsigned int mbedtls_t_udbl __attribute__((mode(TI)));
+ #define MBEDTLS_HAVE_UDBL
+ #endif /* !MBEDTLS_NO_UDBL_DIVISION */
+ #elif defined(__ARMCC_VERSION) && defined(__aarch64__)
+ /*
+ * __ARMCC_VERSION is defined for both armcc and armclang and
+ * __aarch64__ is only defined by armclang when compiling 64-bit code
+ */
+ #if !defined(MBEDTLS_HAVE_INT64)
+ #define MBEDTLS_HAVE_INT64
+ #endif /* !MBEDTLS_HAVE_INT64 */
+ typedef int64_t mbedtls_mpi_sint;
+ typedef uint64_t mbedtls_mpi_uint;
+ #if !defined(MBEDTLS_NO_UDBL_DIVISION)
+ /* mbedtls_t_udbl defined as 128-bit unsigned int */
+ typedef __uint128_t mbedtls_t_udbl;
+ #define MBEDTLS_HAVE_UDBL
+ #endif /* !MBEDTLS_NO_UDBL_DIVISION */
+ #elif defined(MBEDTLS_HAVE_INT64)
+ /* Force 64-bit integers with unknown compiler */
+ typedef int64_t mbedtls_mpi_sint;
+ typedef uint64_t mbedtls_mpi_uint;
+ #endif
+#endif /* !MBEDTLS_HAVE_INT32 */
+
+#if !defined(MBEDTLS_HAVE_INT64)
+ /* Default to 32-bit compilation */
+ #if !defined(MBEDTLS_HAVE_INT32)
+ #define MBEDTLS_HAVE_INT32
+ #endif /* !MBEDTLS_HAVE_INT32 */
+ typedef int32_t mbedtls_mpi_sint;
+ typedef uint32_t mbedtls_mpi_uint;
+ #if !defined(MBEDTLS_NO_UDBL_DIVISION)
+ typedef uint64_t mbedtls_t_udbl;
+ #define MBEDTLS_HAVE_UDBL
+ #endif /* !MBEDTLS_NO_UDBL_DIVISION */
+#endif /* !MBEDTLS_HAVE_INT64 */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief MPI structure
+ */
+typedef struct mbedtls_mpi
+{
+ int s; /*!< Sign: -1 if the mpi is negative, 1 otherwise */
+ size_t n; /*!< total # of limbs */
+ mbedtls_mpi_uint *p; /*!< pointer to limbs */
+}
+mbedtls_mpi;
+
+/**
+ * \brief Initialize an MPI context.
+ *
+ * This makes the MPI ready to be set or freed,
+ * but does not define a value for the MPI.
+ *
+ * \param X The MPI context to initialize. This must not be \c NULL.
+ */
+void mbedtls_mpi_init( mbedtls_mpi *X );
+
+/**
+ * \brief This function frees the components of an MPI context.
+ *
+ * \param X The MPI context to be cleared. This may be \c NULL,
+ * in which case this function is a no-op. If it is
+ * not \c NULL, it must point to an initialized MPI.
+ */
+void mbedtls_mpi_free( mbedtls_mpi *X );
+
+/**
+ * \brief Enlarge an MPI to the specified number of limbs.
+ *
+ * \note This function does nothing if the MPI is
+ * already large enough.
+ *
+ * \param X The MPI to grow. It must be initialized.
+ * \param nblimbs The target number of limbs.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_grow( mbedtls_mpi *X, size_t nblimbs );
+
+/**
+ * \brief This function resizes an MPI downwards, keeping at least the
+ * specified number of limbs.
+ *
+ * If \c X is smaller than \c nblimbs, it is resized up
+ * instead.
+ *
+ * \param X The MPI to shrink. This must point to an initialized MPI.
+ * \param nblimbs The minimum number of limbs to keep.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * (this can only happen when resizing up).
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_shrink( mbedtls_mpi *X, size_t nblimbs );
+
+/**
+ * \brief Make a copy of an MPI.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param Y The source MPI. This must point to an initialized MPI.
+ *
+ * \note The limb-buffer in the destination MPI is enlarged
+ * if necessary to hold the value in the source MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_copy( mbedtls_mpi *X, const mbedtls_mpi *Y );
+
+/**
+ * \brief Swap the contents of two MPIs.
+ *
+ * \param X The first MPI. It must be initialized.
+ * \param Y The second MPI. It must be initialized.
+ */
+void mbedtls_mpi_swap( mbedtls_mpi *X, mbedtls_mpi *Y );
+
+/**
+ * \brief Perform a safe conditional copy of MPI which doesn't
+ * reveal whether the condition was true or not.
+ *
+ * \param X The MPI to conditionally assign to. This must point
+ * to an initialized MPI.
+ * \param Y The MPI to be assigned from. This must point to an
+ * initialized MPI.
+ * \param assign The condition deciding whether to perform the
+ * assignment or not. Possible values:
+ * * \c 1: Perform the assignment `X = Y`.
+ * * \c 0: Keep the original value of \p X.
+ *
+ * \note This function is equivalent to
+ * `if( assign ) mbedtls_mpi_copy( X, Y );`
+ * except that it avoids leaking any information about whether
+ * the assignment was done or not (the above code may leak
+ * information through branch prediction and/or memory access
+ * patterns analysis).
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_safe_cond_assign( mbedtls_mpi *X, const mbedtls_mpi *Y, unsigned char assign );
+
+/**
+ * \brief Perform a safe conditional swap which doesn't
+ * reveal whether the condition was true or not.
+ *
+ * \param X The first MPI. This must be initialized.
+ * \param Y The second MPI. This must be initialized.
+ * \param assign The condition deciding whether to perform
+ * the swap or not. Possible values:
+ * * \c 1: Swap the values of \p X and \p Y.
+ * * \c 0: Keep the original values of \p X and \p Y.
+ *
+ * \note This function is equivalent to
+ * if( assign ) mbedtls_mpi_swap( X, Y );
+ * except that it avoids leaking any information about whether
+ * the assignment was done or not (the above code may leak
+ * information through branch prediction and/or memory access
+ * patterns analysis).
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ *
+ */
+int mbedtls_mpi_safe_cond_swap( mbedtls_mpi *X, mbedtls_mpi *Y, unsigned char assign );
+
+/**
+ * \brief Store integer value in MPI.
+ *
+ * \param X The MPI to set. This must be initialized.
+ * \param z The value to use.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_lset( mbedtls_mpi *X, mbedtls_mpi_sint z );
+
+/**
+ * \brief Get a specific bit from an MPI.
+ *
+ * \param X The MPI to query. This must be initialized.
+ * \param pos Zero-based index of the bit to query.
+ *
+ * \return \c 0 or \c 1 on success, depending on whether bit \c pos
+ * of \c X is unset or set.
+ * \return A negative error code on failure.
+ */
+int mbedtls_mpi_get_bit( const mbedtls_mpi *X, size_t pos );
+
+/**
+ * \brief Modify a specific bit in an MPI.
+ *
+ * \note This function will grow the target MPI if necessary to set a
+ * bit to \c 1 in a not yet existing limb. It will not grow if
+ * the bit should be set to \c 0.
+ *
+ * \param X The MPI to modify. This must be initialized.
+ * \param pos Zero-based index of the bit to modify.
+ * \param val The desired value of bit \c pos: \c 0 or \c 1.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_set_bit( mbedtls_mpi *X, size_t pos, unsigned char val );
+
+/**
+ * \brief Return the number of bits of value \c 0 before the
+ * least significant bit of value \c 1.
+ *
+ * \note This is the same as the zero-based index of
+ * the least significant bit of value \c 1.
+ *
+ * \param X The MPI to query.
+ *
+ * \return The number of bits of value \c 0 before the least significant
+ * bit of value \c 1 in \p X.
+ */
+size_t mbedtls_mpi_lsb( const mbedtls_mpi *X );
+
+/**
+ * \brief Return the number of bits up to and including the most
+ * significant bit of value \c 1.
+ *
+ * * \note This is same as the one-based index of the most
+ * significant bit of value \c 1.
+ *
+ * \param X The MPI to query. This must point to an initialized MPI.
+ *
+ * \return The number of bits up to and including the most
+ * significant bit of value \c 1.
+ */
+size_t mbedtls_mpi_bitlen( const mbedtls_mpi *X );
+
+/**
+ * \brief Return the total size of an MPI value in bytes.
+ *
+ * \param X The MPI to use. This must point to an initialized MPI.
+ *
+ * \note The value returned by this function may be less than
+ * the number of bytes used to store \p X internally.
+ * This happens if and only if there are trailing bytes
+ * of value zero.
+ *
+ * \return The least number of bytes capable of storing
+ * the absolute value of \p X.
+ */
+size_t mbedtls_mpi_size( const mbedtls_mpi *X );
+
+/**
+ * \brief Import an MPI from an ASCII string.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param radix The numeric base of the input string.
+ * \param s Null-terminated string buffer.
+ *
+ * \return \c 0 if successful.
+ * \return A negative error code on failure.
+ */
+int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s );
+
+/**
+ * \brief Export an MPI to an ASCII string.
+ *
+ * \param X The source MPI. This must point to an initialized MPI.
+ * \param radix The numeric base of the output string.
+ * \param buf The buffer to write the string to. This must be writable
+ * buffer of length \p buflen Bytes.
+ * \param buflen The available size in Bytes of \p buf.
+ * \param olen The address at which to store the length of the string
+ * written, including the final \c NULL byte. This must
+ * not be \c NULL.
+ *
+ * \note You can call this function with `buflen == 0` to obtain the
+ * minimum required buffer size in `*olen`.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if the target buffer \p buf
+ * is too small to hold the value of \p X in the desired base.
+ * In this case, `*olen` is nonetheless updated to contain the
+ * size of \p buf required for a successful call.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix,
+ char *buf, size_t buflen, size_t *olen );
+
+#if defined(MBEDTLS_FS_IO)
+/**
+ * \brief Read an MPI from a line in an opened file.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param radix The numeric base of the string representation used
+ * in the source line.
+ * \param fin The input file handle to use. This must not be \c NULL.
+ *
+ * \note On success, this function advances the file stream
+ * to the end of the current line or to EOF.
+ *
+ * The function returns \c 0 on an empty line.
+ *
+ * Leading whitespaces are ignored, as is a
+ * '0x' prefix for radix \c 16.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if the file read buffer
+ * is too small.
+ * \return Another negative error code on failure.
+ */
+int mbedtls_mpi_read_file( mbedtls_mpi *X, int radix, FILE *fin );
+
+/**
+ * \brief Export an MPI into an opened file.
+ *
+ * \param p A string prefix to emit prior to the MPI data.
+ * For example, this might be a label, or "0x" when
+ * printing in base \c 16. This may be \c NULL if no prefix
+ * is needed.
+ * \param X The source MPI. This must point to an initialized MPI.
+ * \param radix The numeric base to be used in the emitted string.
+ * \param fout The output file handle. This may be \c NULL, in which case
+ * the output is written to \c stdout.
+ *
+ * \return \c 0 if successful.
+ * \return A negative error code on failure.
+ */
+int mbedtls_mpi_write_file( const char *p, const mbedtls_mpi *X,
+ int radix, FILE *fout );
+#endif /* MBEDTLS_FS_IO */
+
+/**
+ * \brief Import an MPI from unsigned big endian binary data.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param buf The input buffer. This must be a readable buffer of length
+ * \p buflen Bytes.
+ * \param buflen The length of the input buffer \p p in Bytes.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_read_binary( mbedtls_mpi *X, const unsigned char *buf,
+ size_t buflen );
+
+/**
+ * \brief Import X from unsigned binary data, little endian
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param buf The input buffer. This must be a readable buffer of length
+ * \p buflen Bytes.
+ * \param buflen The length of the input buffer \p p in Bytes.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_read_binary_le( mbedtls_mpi *X,
+ const unsigned char *buf, size_t buflen );
+
+/**
+ * \brief Export X into unsigned binary data, big endian.
+ * Always fills the whole buffer, which will start with zeros
+ * if the number is smaller.
+ *
+ * \param X The source MPI. This must point to an initialized MPI.
+ * \param buf The output buffer. This must be a writable buffer of length
+ * \p buflen Bytes.
+ * \param buflen The size of the output buffer \p buf in Bytes.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if \p buf isn't
+ * large enough to hold the value of \p X.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_write_binary( const mbedtls_mpi *X, unsigned char *buf,
+ size_t buflen );
+
+/**
+ * \brief Export X into unsigned binary data, little endian.
+ * Always fills the whole buffer, which will end with zeros
+ * if the number is smaller.
+ *
+ * \param X The source MPI. This must point to an initialized MPI.
+ * \param buf The output buffer. This must be a writable buffer of length
+ * \p buflen Bytes.
+ * \param buflen The size of the output buffer \p buf in Bytes.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if \p buf isn't
+ * large enough to hold the value of \p X.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_write_binary_le( const mbedtls_mpi *X,
+ unsigned char *buf, size_t buflen );
+
+/**
+ * \brief Perform a left-shift on an MPI: X <<= count
+ *
+ * \param X The MPI to shift. This must point to an initialized MPI.
+ * \param count The number of bits to shift by.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_shift_l( mbedtls_mpi *X, size_t count );
+
+/**
+ * \brief Perform a right-shift on an MPI: X >>= count
+ *
+ * \param X The MPI to shift. This must point to an initialized MPI.
+ * \param count The number of bits to shift by.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_shift_r( mbedtls_mpi *X, size_t count );
+
+/**
+ * \brief Compare the absolute values of two MPIs.
+ *
+ * \param X The left-hand MPI. This must point to an initialized MPI.
+ * \param Y The right-hand MPI. This must point to an initialized MPI.
+ *
+ * \return \c 1 if `|X|` is greater than `|Y|`.
+ * \return \c -1 if `|X|` is lesser than `|Y|`.
+ * \return \c 0 if `|X|` is equal to `|Y|`.
+ */
+int mbedtls_mpi_cmp_abs( const mbedtls_mpi *X, const mbedtls_mpi *Y );
+
+/**
+ * \brief Compare two MPIs.
+ *
+ * \param X The left-hand MPI. This must point to an initialized MPI.
+ * \param Y The right-hand MPI. This must point to an initialized MPI.
+ *
+ * \return \c 1 if \p X is greater than \p Y.
+ * \return \c -1 if \p X is lesser than \p Y.
+ * \return \c 0 if \p X is equal to \p Y.
+ */
+int mbedtls_mpi_cmp_mpi( const mbedtls_mpi *X, const mbedtls_mpi *Y );
+
+/**
+ * \brief Check if an MPI is less than the other in constant time.
+ *
+ * \param X The left-hand MPI. This must point to an initialized MPI
+ * with the same allocated length as Y.
+ * \param Y The right-hand MPI. This must point to an initialized MPI
+ * with the same allocated length as X.
+ * \param ret The result of the comparison:
+ * \c 1 if \p X is less than \p Y.
+ * \c 0 if \p X is greater than or equal to \p Y.
+ *
+ * \return 0 on success.
+ * \return MBEDTLS_ERR_MPI_BAD_INPUT_DATA if the allocated length of
+ * the two input MPIs is not the same.
+ */
+int mbedtls_mpi_lt_mpi_ct( const mbedtls_mpi *X, const mbedtls_mpi *Y,
+ unsigned *ret );
+
+/**
+ * \brief Compare an MPI with an integer.
+ *
+ * \param X The left-hand MPI. This must point to an initialized MPI.
+ * \param z The integer value to compare \p X to.
+ *
+ * \return \c 1 if \p X is greater than \p z.
+ * \return \c -1 if \p X is lesser than \p z.
+ * \return \c 0 if \p X is equal to \p z.
+ */
+int mbedtls_mpi_cmp_int( const mbedtls_mpi *X, mbedtls_mpi_sint z );
+
+/**
+ * \brief Perform an unsigned addition of MPIs: X = |A| + |B|
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The first summand. This must point to an initialized MPI.
+ * \param B The second summand. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_add_abs( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform an unsigned subtraction of MPIs: X = |A| - |B|
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The minuend. This must point to an initialized MPI.
+ * \param B The subtrahend. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_NEGATIVE_VALUE if \p B is greater than \p A.
+ * \return Another negative error code on different kinds of failure.
+ *
+ */
+int mbedtls_mpi_sub_abs( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a signed addition of MPIs: X = A + B
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The first summand. This must point to an initialized MPI.
+ * \param B The second summand. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_add_mpi( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a signed subtraction of MPIs: X = A - B
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The minuend. This must point to an initialized MPI.
+ * \param B The subtrahend. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_sub_mpi( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a signed addition of an MPI and an integer: X = A + b
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The first summand. This must point to an initialized MPI.
+ * \param b The second summand.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_add_int( mbedtls_mpi *X, const mbedtls_mpi *A,
+ mbedtls_mpi_sint b );
+
+/**
+ * \brief Perform a signed subtraction of an MPI and an integer:
+ * X = A - b
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The minuend. This must point to an initialized MPI.
+ * \param b The subtrahend.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_sub_int( mbedtls_mpi *X, const mbedtls_mpi *A,
+ mbedtls_mpi_sint b );
+
+/**
+ * \brief Perform a multiplication of two MPIs: X = A * B
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The first factor. This must point to an initialized MPI.
+ * \param B The second factor. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ *
+ */
+int mbedtls_mpi_mul_mpi( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a multiplication of an MPI with an unsigned integer:
+ * X = A * b
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The first factor. This must point to an initialized MPI.
+ * \param b The second factor.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ *
+ */
+int mbedtls_mpi_mul_int( mbedtls_mpi *X, const mbedtls_mpi *A,
+ mbedtls_mpi_uint b );
+
+/**
+ * \brief Perform a division with remainder of two MPIs:
+ * A = Q * B + R
+ *
+ * \param Q The destination MPI for the quotient.
+ * This may be \c NULL if the value of the
+ * quotient is not needed.
+ * \param R The destination MPI for the remainder value.
+ * This may be \c NULL if the value of the
+ * remainder is not needed.
+ * \param A The dividend. This must point to an initialized MPi.
+ * \param B The divisor. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p B equals zero.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_div_mpi( mbedtls_mpi *Q, mbedtls_mpi *R, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a division with remainder of an MPI by an integer:
+ * A = Q * b + R
+ *
+ * \param Q The destination MPI for the quotient.
+ * This may be \c NULL if the value of the
+ * quotient is not needed.
+ * \param R The destination MPI for the remainder value.
+ * This may be \c NULL if the value of the
+ * remainder is not needed.
+ * \param A The dividend. This must point to an initialized MPi.
+ * \param b The divisor.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p b equals zero.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_div_int( mbedtls_mpi *Q, mbedtls_mpi *R, const mbedtls_mpi *A,
+ mbedtls_mpi_sint b );
+
+/**
+ * \brief Perform a modular reduction. R = A mod B
+ *
+ * \param R The destination MPI for the residue value.
+ * This must point to an initialized MPI.
+ * \param A The MPI to compute the residue of.
+ * This must point to an initialized MPI.
+ * \param B The base of the modular reduction.
+ * This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p B equals zero.
+ * \return #MBEDTLS_ERR_MPI_NEGATIVE_VALUE if \p B is negative.
+ * \return Another negative error code on different kinds of failure.
+ *
+ */
+int mbedtls_mpi_mod_mpi( mbedtls_mpi *R, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Perform a modular reduction with respect to an integer.
+ * r = A mod b
+ *
+ * \param r The address at which to store the residue.
+ * This must not be \c NULL.
+ * \param A The MPI to compute the residue of.
+ * This must point to an initialized MPi.
+ * \param b The integer base of the modular reduction.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p b equals zero.
+ * \return #MBEDTLS_ERR_MPI_NEGATIVE_VALUE if \p b is negative.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_mod_int( mbedtls_mpi_uint *r, const mbedtls_mpi *A,
+ mbedtls_mpi_sint b );
+
+/**
+ * \brief Perform a sliding-window exponentiation: X = A^E mod N
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The base of the exponentiation.
+ * This must point to an initialized MPI.
+ * \param E The exponent MPI. This must point to an initialized MPI.
+ * \param N The base for the modular reduction. This must point to an
+ * initialized MPI.
+ * \param _RR A helper MPI depending solely on \p N which can be used to
+ * speed-up multiple modular exponentiations for the same value
+ * of \p N. This may be \c NULL. If it is not \c NULL, it must
+ * point to an initialized MPI. If it hasn't been used after
+ * the call to mbedtls_mpi_init(), this function will compute
+ * the helper value and store it in \p _RR for reuse on
+ * subsequent calls to this function. Otherwise, the function
+ * will assume that \p _RR holds the helper value set by a
+ * previous call to mbedtls_mpi_exp_mod(), and reuse it.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \c N is negative or
+ * even, or if \c E is negative.
+ * \return Another negative error code on different kinds of failures.
+ *
+ */
+int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *E, const mbedtls_mpi *N,
+ mbedtls_mpi *_RR );
+
+/**
+ * \brief Fill an MPI with a number of random bytes.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param size The number of random bytes to generate.
+ * \param f_rng The RNG function to use. This must not be \c NULL.
+ * \param p_rng The RNG parameter to be passed to \p f_rng. This may be
+ * \c NULL if \p f_rng doesn't need a context argument.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on failure.
+ *
+ * \note The bytes obtained from the RNG are interpreted
+ * as a big-endian representation of an MPI; this can
+ * be relevant in applications like deterministic ECDSA.
+ */
+int mbedtls_mpi_fill_random( mbedtls_mpi *X, size_t size,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+
+/** Generate a random number uniformly in a range.
+ *
+ * This function generates a random number between \p min inclusive and
+ * \p N exclusive.
+ *
+ * The procedure complies with RFC 6979 ยง3.3 (deterministic ECDSA)
+ * when the RNG is a suitably parametrized instance of HMAC_DRBG
+ * and \p min is \c 1.
+ *
+ * \note There are `N - min` possible outputs. The lower bound
+ * \p min can be reached, but the upper bound \p N cannot.
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param min The minimum value to return.
+ * It must be nonnegative.
+ * \param N The upper bound of the range, exclusive.
+ * In other words, this is one plus the maximum value to return.
+ * \p N must be strictly larger than \p min.
+ * \param f_rng The RNG function to use. This must not be \c NULL.
+ * \param p_rng The RNG parameter to be passed to \p f_rng.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p min or \p N is invalid
+ * or if they are incompatible.
+ * \return #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if the implementation was
+ * unable to find a suitable value within a limited number
+ * of attempts. This has a negligible probability if \p N
+ * is significantly larger than \p min, which is the case
+ * for all usual cryptographic applications.
+ * \return Another negative error code on failure.
+ */
+int mbedtls_mpi_random( mbedtls_mpi *X,
+ mbedtls_mpi_sint min,
+ const mbedtls_mpi *N,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+
+/**
+ * \brief Compute the greatest common divisor: G = gcd(A, B)
+ *
+ * \param G The destination MPI. This must point to an initialized MPI.
+ * \param A The first operand. This must point to an initialized MPI.
+ * \param B The second operand. This must point to an initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_gcd( mbedtls_mpi *G, const mbedtls_mpi *A,
+ const mbedtls_mpi *B );
+
+/**
+ * \brief Compute the modular inverse: X = A^-1 mod N
+ *
+ * \param X The destination MPI. This must point to an initialized MPI.
+ * \param A The MPI to calculate the modular inverse of. This must point
+ * to an initialized MPI.
+ * \param N The base of the modular inversion. This must point to an
+ * initialized MPI.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p N is less than
+ * or equal to one.
+ * \return #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if \p has no modular inverse
+ * with respect to \p N.
+ */
+int mbedtls_mpi_inv_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
+ const mbedtls_mpi *N );
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
+/**
+ * \brief Perform a Miller-Rabin primality test with error
+ * probability of 2<sup>-80</sup>.
+ *
+ * \deprecated Superseded by mbedtls_mpi_is_prime_ext() which allows
+ * specifying the number of Miller-Rabin rounds.
+ *
+ * \param X The MPI to check for primality.
+ * This must point to an initialized MPI.
+ * \param f_rng The RNG function to use. This must not be \c NULL.
+ * \param p_rng The RNG parameter to be passed to \p f_rng.
+ * This may be \c NULL if \p f_rng doesn't use a
+ * context parameter.
+ *
+ * \return \c 0 if successful, i.e. \p X is probably prime.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if \p X is not prime.
+ * \return Another negative error code on other kinds of failure.
+ */
+MBEDTLS_DEPRECATED int mbedtls_mpi_is_prime( const mbedtls_mpi *X,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+#undef MBEDTLS_DEPRECATED
+#endif /* !MBEDTLS_DEPRECATED_REMOVED */
+
+/**
+ * \brief Miller-Rabin primality test.
+ *
+ * \warning If \p X is potentially generated by an adversary, for example
+ * when validating cryptographic parameters that you didn't
+ * generate yourself and that are supposed to be prime, then
+ * \p rounds should be at least the half of the security
+ * strength of the cryptographic algorithm. On the other hand,
+ * if \p X is chosen uniformly or non-adversially (as is the
+ * case when mbedtls_mpi_gen_prime calls this function), then
+ * \p rounds can be much lower.
+ *
+ * \param X The MPI to check for primality.
+ * This must point to an initialized MPI.
+ * \param rounds The number of bases to perform the Miller-Rabin primality
+ * test for. The probability of returning 0 on a composite is
+ * at most 2<sup>-2*\p rounds</sup>.
+ * \param f_rng The RNG function to use. This must not be \c NULL.
+ * \param p_rng The RNG parameter to be passed to \p f_rng.
+ * This may be \c NULL if \p f_rng doesn't use
+ * a context parameter.
+ *
+ * \return \c 0 if successful, i.e. \p X is probably prime.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if \p X is not prime.
+ * \return Another negative error code on other kinds of failure.
+ */
+int mbedtls_mpi_is_prime_ext( const mbedtls_mpi *X, int rounds,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+/**
+ * \brief Flags for mbedtls_mpi_gen_prime()
+ *
+ * Each of these flags is a constraint on the result X returned by
+ * mbedtls_mpi_gen_prime().
+ */
+typedef enum {
+ MBEDTLS_MPI_GEN_PRIME_FLAG_DH = 0x0001, /**< (X-1)/2 is prime too */
+ MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR = 0x0002, /**< lower error rate from 2<sup>-80</sup> to 2<sup>-128</sup> */
+} mbedtls_mpi_gen_prime_flag_t;
+
+/**
+ * \brief Generate a prime number.
+ *
+ * \param X The destination MPI to store the generated prime in.
+ * This must point to an initialized MPi.
+ * \param nbits The required size of the destination MPI in bits.
+ * This must be between \c 3 and #MBEDTLS_MPI_MAX_BITS.
+ * \param flags A mask of flags of type #mbedtls_mpi_gen_prime_flag_t.
+ * \param f_rng The RNG function to use. This must not be \c NULL.
+ * \param p_rng The RNG parameter to be passed to \p f_rng.
+ * This may be \c NULL if \p f_rng doesn't use
+ * a context parameter.
+ *
+ * \return \c 0 if successful, in which case \p X holds a
+ * probably prime number.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if `nbits` is not between
+ * \c 3 and #MBEDTLS_MPI_MAX_BITS.
+ */
+int mbedtls_mpi_gen_prime( mbedtls_mpi *X, size_t nbits, int flags,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+
+#if defined(MBEDTLS_SELF_TEST)
+
+/**
+ * \brief Checkup routine
+ *
+ * \return 0 if successful, or 1 if the test failed
+ */
+int mbedtls_mpi_self_test( int verbose );
+
+#endif /* MBEDTLS_SELF_TEST */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* bignum.h */