mirror of
https://github.com/godotengine/godot.git
synced 2025-11-03 23:21:15 +00:00
36 lines
947 B
C++
36 lines
947 B
C++
|
/**
|
||
|
|
* \file ctr.h
|
||
|
|
*
|
||
|
|
* \brief This file contains common functionality for counter algorithms.
|
||
|
|
*
|
||
|
|
* Copyright The Mbed TLS Contributors
|
||
|
|
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef MBEDTLS_CTR_H
|
||
|
|
#define MBEDTLS_CTR_H
|
||
|
|
|
||
|
|
#include "common.h"
|
||
|
|
|
||
|
|
/**
|
||
|
|
* \brief Increment a big-endian 16-byte value.
|
||
|
|
* This is quite performance-sensitive for AES-CTR and CTR-DRBG.
|
||
|
|
*
|
||
|
|
* \param n A 16-byte value to be incremented.
|
||
|
|
*/
|
||
|
|
static inline void mbedtls_ctr_increment_counter(uint8_t n[16])
|
||
|
|
{
|
||
|
|
// The 32-bit version seems to perform about the same as a 64-bit version
|
||
|
|
// on 64-bit architectures, so no need to define a 64-bit version.
|
||
|
|
for (int i = 3;; i--) {
|
||
|
|
uint32_t x = MBEDTLS_GET_UINT32_BE(n, i << 2);
|
||
|
|
x += 1;
|
||
|
|
MBEDTLS_PUT_UINT32_BE(x, n, i << 2);
|
||
|
|
if (x != 0 || i == 0) {
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* MBEDTLS_CTR_H */
|