| /** |
| * 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_H |
| #define MBEDTLS_CONSTANT_TIME_H |
| |
| #include <stddef.h> |
| |
| |
| /** Constant-time buffer comparison without branches. |
| * |
| * This is equivalent to the standard memcmp function, but is likely to be |
| * compiled to code using bitwise operation rather than a branch. |
| * |
| * This function can be used to write constant-time code by replacing branches |
| * with bit operations using masks. |
| * |
| * \param a Pointer to the first buffer. |
| * \param b Pointer to the second buffer. |
| * \param n The number of bytes to compare in the buffer. |
| * |
| * \return Zero if the content of the two buffer is the same, |
| * otherwise non-zero. |
| */ |
| int mbedtls_ct_memcmp( const void *a, |
| const void *b, |
| size_t n ); |
| |
| #endif /* MBEDTLS_CONSTANT_TIME_H */ |