diff options
Diffstat (limited to 'thirdparty/mbedtls/library/constant_time_internal.h')
| -rw-r--r-- | thirdparty/mbedtls/library/constant_time_internal.h | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/thirdparty/mbedtls/library/constant_time_internal.h b/thirdparty/mbedtls/library/constant_time_internal.h new file mode 100644 index 0000000000..bbb3a90670 --- /dev/null +++ b/thirdparty/mbedtls/library/constant_time_internal.h @@ -0,0 +1,329 @@ +/** + * Constant-time functions + * + * 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_CONSTANT_TIME_INTERNAL_H +#define MBEDTLS_CONSTANT_TIME_INTERNAL_H + +#include "common.h" + +#if defined(MBEDTLS_BIGNUM_C) +#include "mbedtls/bignum.h" +#endif + +#if defined(MBEDTLS_SSL_TLS_C) +#include "mbedtls/ssl_internal.h" +#endif + +#include <stddef.h> + + +/** Turn a value into a mask: + * - if \p value == 0, return the all-bits 0 mask, aka 0 + * - otherwise, return the all-bits 1 mask, aka (unsigned) -1 + * + * This function can be used to write constant-time code by replacing branches + * with bit operations using masks. + * + * \param value The value to analyze. + * + * \return Zero if \p value is zero, otherwise all-bits-one. + */ +unsigned mbedtls_ct_uint_mask( unsigned value ); + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC) + +/** Turn a value into a mask: + * - if \p value == 0, return the all-bits 0 mask, aka 0 + * - otherwise, return the all-bits 1 mask, aka (size_t) -1 + * + * This function can be used to write constant-time code by replacing branches + * with bit operations using masks. + * + * \param value The value to analyze. + * + * \return Zero if \p value is zero, otherwise all-bits-one. + */ +size_t mbedtls_ct_size_mask( size_t value ); + +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC */ + +#if defined(MBEDTLS_BIGNUM_C) + +/** Turn a value into a mask: + * - if \p value == 0, return the all-bits 0 mask, aka 0 + * - otherwise, return the all-bits 1 mask, aka (mbedtls_mpi_uint) -1 + * + * This function can be used to write constant-time code by replacing branches + * with bit operations using masks. + * + * \param value The value to analyze. + * + * \return Zero if \p value is zero, otherwise all-bits-one. + */ +mbedtls_mpi_uint mbedtls_ct_mpi_uint_mask( mbedtls_mpi_uint value ); + +#endif /* MBEDTLS_BIGNUM_C */ + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC) + +/** Constant-flow mask generation for "greater or equal" comparison: + * - if \p x >= \p y, return all-bits 1, that is (size_t) -1 + * - otherwise, return all bits 0, that is 0 + * + * This function can be used to write constant-time code by replacing branches + * with bit operations using masks. + * + * \param x The first value to analyze. + * \param y The second value to analyze. + * + * \return All-bits-one if \p x is greater or equal than \p y, + * otherwise zero. + */ +size_t mbedtls_ct_size_mask_ge( size_t x, + size_t y ); + +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC */ + +/** Constant-flow boolean "equal" comparison: + * return x == y + * + * This is equivalent to \p x == \p y, but is likely to be compiled + * to code using bitwise operation rather than a branch. + * + * \param x The first value to analyze. + * \param y The second value to analyze. + * + * \return 1 if \p x equals to \p y, otherwise 0. + */ +unsigned mbedtls_ct_size_bool_eq( size_t x, + size_t y ); + +#if defined(MBEDTLS_BIGNUM_C) + +/** Decide if an integer is less than the other, without branches. + * + * This is equivalent to \p x < \p y, but is likely to be compiled + * to code using bitwise operation rather than a branch. + * + * \param x The first value to analyze. + * \param y The second value to analyze. + * + * \return 1 if \p x is less than \p y, otherwise 0. + */ +unsigned mbedtls_ct_mpi_uint_lt( const mbedtls_mpi_uint x, + const mbedtls_mpi_uint y ); + +#endif /* MBEDTLS_BIGNUM_C */ + +/** Choose between two integer values without branches. + * + * This is equivalent to `condition ? if1 : if0`, but is likely to be compiled + * to code using bitwise operation rather than a branch. + * + * \param condition Condition to test. + * \param if1 Value to use if \p condition is nonzero. + * \param if0 Value to use if \p condition is zero. + * + * \return \c if1 if \p condition is nonzero, otherwise \c if0. + */ +unsigned mbedtls_ct_uint_if( unsigned condition, + unsigned if1, + unsigned if0 ); + +#if defined(MBEDTLS_BIGNUM_C) + +/** Conditionally assign a value without branches. + * + * This is equivalent to `if ( condition ) dest = src`, but is likely + * to be compiled to code using bitwise operation rather than a branch. + * + * \param n \p dest and \p src must be arrays of limbs of size n. + * \param dest The MPI to conditionally assign to. This must point + * to an initialized MPI. + * \param src The MPI to be assigned from. This must point to an + * initialized MPI. + * \param condition Condition to test, must be 0 or 1. + */ +void mbedtls_ct_mpi_uint_cond_assign( size_t n, + mbedtls_mpi_uint *dest, + const mbedtls_mpi_uint *src, + unsigned char condition ); + +#endif /* MBEDTLS_BIGNUM_C */ + +#if defined(MBEDTLS_BASE64_C) + +/** Given a value in the range 0..63, return the corresponding Base64 digit. + * + * The implementation assumes that letters are consecutive (e.g. ASCII + * but not EBCDIC). + * + * \param value A value in the range 0..63. + * + * \return A base64 digit converted from \p value. + */ +unsigned char mbedtls_ct_base64_enc_char( unsigned char value ); + +/** Given a Base64 digit, return its value. + * + * If c is not a Base64 digit ('A'..'Z', 'a'..'z', '0'..'9', '+' or '/'), + * return -1. + * + * The implementation assumes that letters are consecutive (e.g. ASCII + * but not EBCDIC). + * + * \param c A base64 digit. + * + * \return The value of the base64 digit \p c. + */ +signed char mbedtls_ct_base64_dec_value( unsigned char c ); + +#endif /* MBEDTLS_BASE64_C */ + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC) + +/** Conditional memcpy without branches. + * + * This is equivalent to `if ( c1 == c2 ) memcpy(dest, src, len)`, but is likely + * to be compiled to code using bitwise operation rather than a branch. + * + * \param dest The pointer to conditionally copy to. + * \param src The pointer to copy from. Shouldn't overlap with \p dest. + * \param len The number of bytes to copy. + * \param c1 The first value to analyze in the condition. + * \param c2 The second value to analyze in the condition. + */ +void mbedtls_ct_memcpy_if_eq( unsigned char *dest, + const unsigned char *src, + size_t len, + size_t c1, size_t c2 ); + +/** Copy data from a secret position with constant flow. + * + * This function copies \p len bytes from \p src_base + \p offset_secret to \p + * dst, with a code flow and memory access pattern that does not depend on \p + * offset_secret, but only on \p offset_min, \p offset_max and \p len. + * Functionally equivalent to `memcpy(dst, src + offset_secret, len)`. + * + * \param dest The destination buffer. This must point to a writable + * buffer of at least \p len bytes. + * \param src The base of the source buffer. This must point to a + * readable buffer of at least \p offset_max + \p len + * bytes. Shouldn't overlap with \p dest. + * \param offset The offset in the source buffer from which to copy. + * This must be no less than \p offset_min and no greater + * than \p offset_max. + * \param offset_min The minimal value of \p offset. + * \param offset_max The maximal value of \p offset. + * \param len The number of bytes to copy. + */ +void mbedtls_ct_memcpy_offset( unsigned char *dest, + const unsigned char *src, + size_t offset, + size_t offset_min, + size_t offset_max, + size_t len ); + +/** Compute the HMAC of variable-length data with constant flow. + * + * This function computes the HMAC of the concatenation of \p add_data and \p + * data, and does with a code flow and memory access pattern that does not + * depend on \p data_len_secret, but only on \p min_data_len and \p + * max_data_len. In particular, this function always reads exactly \p + * max_data_len bytes from \p data. + * + * \param ctx The HMAC context. It must have keys configured + * with mbedtls_md_hmac_starts() and use one of the + * following hashes: SHA-384, SHA-256, SHA-1 or MD-5. + * It is reset using mbedtls_md_hmac_reset() after + * the computation is complete to prepare for the + * next computation. + * \param add_data The first part of the message whose HMAC is being + * calculated. This must point to a readable buffer + * of \p add_data_len bytes. + * \param add_data_len The length of \p add_data in bytes. + * \param data The buffer containing the second part of the + * message. This must point to a readable buffer + * of \p max_data_len bytes. + * \param data_len_secret The length of the data to process in \p data. + * This must be no less than \p min_data_len and no + * greater than \p max_data_len. + * \param min_data_len The minimal length of the second part of the + * message, read from \p data. + * \param max_data_len The maximal length of the second part of the + * message, read from \p data. + * \param output The HMAC will be written here. This must point to + * a writable buffer of sufficient size to hold the + * HMAC value. + * + * \retval 0 on success. + * \retval #MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED + * The hardware accelerator failed. + */ +int mbedtls_ct_hmac( mbedtls_md_context_t *ctx, + const unsigned char *add_data, + size_t add_data_len, + const unsigned char *data, + size_t data_len_secret, + size_t min_data_len, + size_t max_data_len, + unsigned char *output ); + +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC */ + +#if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT) + +/** This function performs the unpadding part of a PKCS#1 v1.5 decryption + * operation (EME-PKCS1-v1_5 decoding). + * + * \note The return value from this function is a sensitive value + * (this is unusual). #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE shouldn't happen + * in a well-written application, but 0 vs #MBEDTLS_ERR_RSA_INVALID_PADDING + * is often a situation that an attacker can provoke and leaking which + * one is the result is precisely the information the attacker wants. + * + * \param mode The mode of operation. This must be either + * #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated). + * \param input The input buffer which is the payload inside PKCS#1v1.5 + * encryption padding, called the "encoded message EM" + * by the terminology. + * \param ilen The length of the payload in the \p input buffer. + * \param output The buffer for the payload, called "message M" by the + * PKCS#1 terminology. This must be a writable buffer of + * length \p output_max_len bytes. + * \param olen The address at which to store the length of + * the payload. This must not be \c NULL. + * \param output_max_len The length in bytes of the output buffer \p output. + * + * \return \c 0 on success. + * \return #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE + * The output buffer is too small for the unpadded payload. + * \return #MBEDTLS_ERR_RSA_INVALID_PADDING + * The input doesn't contain properly formatted padding. + */ +int mbedtls_ct_rsaes_pkcs1_v15_unpadding( int mode, + unsigned char *input, + size_t ilen, + unsigned char *output, + size_t output_max_len, + size_t *olen ); + +#endif /* MBEDTLS_PKCS1_V15 && MBEDTLS_RSA_C && ! MBEDTLS_RSA_ALT */ + +#endif /* MBEDTLS_CONSTANT_TIME_INTERNAL_H */ |