535 lines
16 KiB
C
535 lines
16 KiB
C
/*
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* NIST SP800-38C compliant CCM implementation
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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/*
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* Definition of CCM:
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* http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf
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* RFC 3610 "Counter with CBC-MAC (CCM)"
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*
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* Related:
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* RFC 5116 "An Interface and Algorithms for Authenticated Encryption"
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*/
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#include "common.h"
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#if defined(MBEDTLS_CCM_C)
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#include "mbedtls/ccm.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/error.h"
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#include "mbedtls/constant_time.h"
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#include <string.h>
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#include "mbedtls/platform.h"
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#if !defined(MBEDTLS_CCM_ALT)
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#define CCM_VALIDATE_RET(cond) \
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MBEDTLS_INTERNAL_VALIDATE_RET(cond, MBEDTLS_ERR_CCM_BAD_INPUT)
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#define CCM_VALIDATE(cond) \
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MBEDTLS_INTERNAL_VALIDATE(cond)
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#define CCM_ENCRYPT 0
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#define CCM_DECRYPT 1
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/*
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* Initialize context
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*/
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void mbedtls_ccm_init(mbedtls_ccm_context *ctx)
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{
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CCM_VALIDATE(ctx != NULL);
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memset(ctx, 0, sizeof(mbedtls_ccm_context));
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}
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int mbedtls_ccm_setkey(mbedtls_ccm_context *ctx,
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mbedtls_cipher_id_t cipher,
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const unsigned char *key,
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unsigned int keybits)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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const mbedtls_cipher_info_t *cipher_info;
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CCM_VALIDATE_RET(ctx != NULL);
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CCM_VALIDATE_RET(key != NULL);
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cipher_info = mbedtls_cipher_info_from_values(cipher, keybits,
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MBEDTLS_MODE_ECB);
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if (cipher_info == NULL) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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if (cipher_info->block_size != 16) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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mbedtls_cipher_free(&ctx->cipher_ctx);
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if ((ret = mbedtls_cipher_setup(&ctx->cipher_ctx, cipher_info)) != 0) {
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return ret;
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}
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if ((ret = mbedtls_cipher_setkey(&ctx->cipher_ctx, key, keybits,
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MBEDTLS_ENCRYPT)) != 0) {
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return ret;
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}
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return 0;
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}
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/*
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* Free context
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*/
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void mbedtls_ccm_free(mbedtls_ccm_context *ctx)
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{
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if (ctx == NULL) {
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return;
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}
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mbedtls_cipher_free(&ctx->cipher_ctx);
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mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ccm_context));
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}
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/*
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* Macros for common operations.
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* Results in smaller compiled code than static inline functions.
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*/
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/*
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* Update the CBC-MAC state in y using a block in b
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* (Always using b as the source helps the compiler optimise a bit better.)
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*/
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#define UPDATE_CBC_MAC \
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for (i = 0; i < 16; i++) \
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y[i] ^= b[i]; \
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\
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if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, y, 16, y, &olen)) != 0) \
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return ret;
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/*
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* Encrypt or decrypt a partial block with CTR
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* Warning: using b for temporary storage! src and dst must not be b!
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* This avoids allocating one more 16 bytes buffer while allowing src == dst.
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*/
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#define CTR_CRYPT(dst, src, len) \
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do \
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{ \
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if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctr, \
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16, b, &olen)) != 0) \
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{ \
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return ret; \
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} \
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\
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for (i = 0; i < (len); i++) \
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(dst)[i] = (src)[i] ^ b[i]; \
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} while (0)
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/*
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* Authenticated encryption or decryption
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*/
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static int ccm_auth_crypt(mbedtls_ccm_context *ctx, int mode, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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unsigned char *tag, size_t tag_len)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char i;
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unsigned char q;
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size_t len_left, olen;
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unsigned char b[16];
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unsigned char y[16];
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unsigned char ctr[16];
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const unsigned char *src;
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unsigned char *dst;
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/*
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* Check length requirements: SP800-38C A.1
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* Additional requirement: a < 2^16 - 2^8 to simplify the code.
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* 'length' checked later (when writing it to the first block)
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*
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* Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4).
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*/
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if (tag_len == 2 || tag_len > 16 || tag_len % 2 != 0) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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/* Also implies q is within bounds */
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if (iv_len < 7 || iv_len > 13) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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if (add_len >= 0xFF00) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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q = 16 - 1 - (unsigned char) iv_len;
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/*
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* First block B_0:
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* 0 .. 0 flags
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* 1 .. iv_len nonce (aka iv)
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* iv_len+1 .. 15 length
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*
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* With flags as (bits):
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* 7 0
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* 6 add present?
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* 5 .. 3 (t - 2) / 2
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* 2 .. 0 q - 1
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*/
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b[0] = 0;
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b[0] |= (add_len > 0) << 6;
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b[0] |= ((tag_len - 2) / 2) << 3;
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b[0] |= q - 1;
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memcpy(b + 1, iv, iv_len);
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for (i = 0, len_left = length; i < q; i++, len_left >>= 8) {
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b[15-i] = MBEDTLS_BYTE_0(len_left);
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}
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if (len_left > 0) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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/* Start CBC-MAC with first block */
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memset(y, 0, 16);
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UPDATE_CBC_MAC;
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/*
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* If there is additional data, update CBC-MAC with
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* add_len, add, 0 (padding to a block boundary)
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*/
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if (add_len > 0) {
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size_t use_len;
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len_left = add_len;
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src = add;
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memset(b, 0, 16);
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MBEDTLS_PUT_UINT16_BE(add_len, b, 0);
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use_len = len_left < 16 - 2 ? len_left : 16 - 2;
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memcpy(b + 2, src, use_len);
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len_left -= use_len;
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src += use_len;
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UPDATE_CBC_MAC;
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while (len_left > 0) {
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use_len = len_left > 16 ? 16 : len_left;
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memset(b, 0, 16);
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memcpy(b, src, use_len);
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UPDATE_CBC_MAC;
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len_left -= use_len;
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src += use_len;
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}
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}
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/*
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* Prepare counter block for encryption:
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* 0 .. 0 flags
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* 1 .. iv_len nonce (aka iv)
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* iv_len+1 .. 15 counter (initially 1)
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*
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* With flags as (bits):
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* 7 .. 3 0
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* 2 .. 0 q - 1
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*/
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ctr[0] = q - 1;
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memcpy(ctr + 1, iv, iv_len);
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memset(ctr + 1 + iv_len, 0, q);
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ctr[15] = 1;
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/*
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* Authenticate and {en,de}crypt the message.
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*
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* The only difference between encryption and decryption is
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* the respective order of authentication and {en,de}cryption.
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*/
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len_left = length;
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src = input;
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dst = output;
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while (len_left > 0) {
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size_t use_len = len_left > 16 ? 16 : len_left;
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if (mode == CCM_ENCRYPT) {
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memset(b, 0, 16);
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memcpy(b, src, use_len);
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UPDATE_CBC_MAC;
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}
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CTR_CRYPT(dst, src, use_len);
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if (mode == CCM_DECRYPT) {
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memset(b, 0, 16);
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memcpy(b, dst, use_len);
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UPDATE_CBC_MAC;
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}
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dst += use_len;
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src += use_len;
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len_left -= use_len;
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/*
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* Increment counter.
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* No need to check for overflow thanks to the length check above.
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*/
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for (i = 0; i < q; i++) {
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if (++ctr[15-i] != 0) {
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break;
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}
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}
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}
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/*
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* Authentication: reset counter and crypt/mask internal tag
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*/
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for (i = 0; i < q; i++) {
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ctr[15-i] = 0;
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}
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CTR_CRYPT(y, y, 16);
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memcpy(tag, y, tag_len);
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return 0;
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}
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/*
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* Authenticated encryption
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*/
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int mbedtls_ccm_star_encrypt_and_tag(mbedtls_ccm_context *ctx, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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unsigned char *tag, size_t tag_len)
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{
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CCM_VALIDATE_RET(ctx != NULL);
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CCM_VALIDATE_RET(iv != NULL);
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CCM_VALIDATE_RET(add_len == 0 || add != NULL);
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CCM_VALIDATE_RET(length == 0 || input != NULL);
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CCM_VALIDATE_RET(length == 0 || output != NULL);
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CCM_VALIDATE_RET(tag_len == 0 || tag != NULL);
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return ccm_auth_crypt(ctx, CCM_ENCRYPT, length, iv, iv_len,
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add, add_len, input, output, tag, tag_len);
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}
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int mbedtls_ccm_encrypt_and_tag(mbedtls_ccm_context *ctx, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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unsigned char *tag, size_t tag_len)
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{
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CCM_VALIDATE_RET(ctx != NULL);
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CCM_VALIDATE_RET(iv != NULL);
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CCM_VALIDATE_RET(add_len == 0 || add != NULL);
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CCM_VALIDATE_RET(length == 0 || input != NULL);
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CCM_VALIDATE_RET(length == 0 || output != NULL);
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CCM_VALIDATE_RET(tag_len == 0 || tag != NULL);
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if (tag_len == 0) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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return mbedtls_ccm_star_encrypt_and_tag(ctx, length, iv, iv_len, add,
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add_len, input, output, tag, tag_len);
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}
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/*
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* Authenticated decryption
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*/
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int mbedtls_ccm_star_auth_decrypt(mbedtls_ccm_context *ctx, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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const unsigned char *tag, size_t tag_len)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char check_tag[16];
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int diff;
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CCM_VALIDATE_RET(ctx != NULL);
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CCM_VALIDATE_RET(iv != NULL);
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CCM_VALIDATE_RET(add_len == 0 || add != NULL);
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CCM_VALIDATE_RET(length == 0 || input != NULL);
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CCM_VALIDATE_RET(length == 0 || output != NULL);
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CCM_VALIDATE_RET(tag_len == 0 || tag != NULL);
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if ((ret = ccm_auth_crypt(ctx, CCM_DECRYPT, length,
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iv, iv_len, add, add_len,
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input, output, check_tag, tag_len)) != 0) {
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return ret;
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}
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/* Check tag in "constant-time" */
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diff = mbedtls_ct_memcmp(tag, check_tag, tag_len);
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if (diff != 0) {
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mbedtls_platform_zeroize(output, length);
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return MBEDTLS_ERR_CCM_AUTH_FAILED;
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}
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return 0;
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}
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int mbedtls_ccm_auth_decrypt(mbedtls_ccm_context *ctx, size_t length,
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const unsigned char *iv, size_t iv_len,
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const unsigned char *add, size_t add_len,
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const unsigned char *input, unsigned char *output,
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const unsigned char *tag, size_t tag_len)
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{
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CCM_VALIDATE_RET(ctx != NULL);
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CCM_VALIDATE_RET(iv != NULL);
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CCM_VALIDATE_RET(add_len == 0 || add != NULL);
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CCM_VALIDATE_RET(length == 0 || input != NULL);
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CCM_VALIDATE_RET(length == 0 || output != NULL);
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CCM_VALIDATE_RET(tag_len == 0 || tag != NULL);
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if (tag_len == 0) {
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return MBEDTLS_ERR_CCM_BAD_INPUT;
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}
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return mbedtls_ccm_star_auth_decrypt(ctx, length, iv, iv_len, add,
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add_len, input, output, tag, tag_len);
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}
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#endif /* !MBEDTLS_CCM_ALT */
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#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
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/*
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* Examples 1 to 3 from SP800-38C Appendix C
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*/
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#define NB_TESTS 3
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#define CCM_SELFTEST_PT_MAX_LEN 24
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#define CCM_SELFTEST_CT_MAX_LEN 32
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/*
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* The data is the same for all tests, only the used length changes
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*/
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static const unsigned char key_test_data[] = {
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0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
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0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
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};
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static const unsigned char iv_test_data[] = {
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1a, 0x1b
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};
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static const unsigned char ad_test_data[] = {
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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0x10, 0x11, 0x12, 0x13
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};
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static const unsigned char msg_test_data[CCM_SELFTEST_PT_MAX_LEN] = {
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0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
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0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
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0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
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};
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static const size_t iv_len_test_data[NB_TESTS] = { 7, 8, 12 };
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static const size_t add_len_test_data[NB_TESTS] = { 8, 16, 20 };
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static const size_t msg_len_test_data[NB_TESTS] = { 4, 16, 24 };
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static const size_t tag_len_test_data[NB_TESTS] = { 4, 6, 8 };
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static const unsigned char res_test_data[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = {
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{ 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
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{ 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
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0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
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0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
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{ 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
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0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
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0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
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0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
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};
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int mbedtls_ccm_self_test(int verbose)
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{
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mbedtls_ccm_context ctx;
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/*
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* Some hardware accelerators require the input and output buffers
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* would be in RAM, because the flash is not accessible.
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* Use buffers on the stack to hold the test vectors data.
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*/
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unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN];
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unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN];
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size_t i;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_ccm_init(&ctx);
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if (mbedtls_ccm_setkey(&ctx, MBEDTLS_CIPHER_ID_AES, key_test_data,
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8 * sizeof(key_test_data)) != 0) {
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if (verbose != 0) {
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mbedtls_printf(" CCM: setup failed");
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}
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return 1;
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}
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for (i = 0; i < NB_TESTS; i++) {
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if (verbose != 0) {
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mbedtls_printf(" CCM-AES #%u: ", (unsigned int) i + 1);
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}
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memset(plaintext, 0, CCM_SELFTEST_PT_MAX_LEN);
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memset(ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN);
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memcpy(plaintext, msg_test_data, msg_len_test_data[i]);
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ret = mbedtls_ccm_encrypt_and_tag(&ctx, msg_len_test_data[i],
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iv_test_data, iv_len_test_data[i],
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ad_test_data, add_len_test_data[i],
|
|
plaintext, ciphertext,
|
|
ciphertext + msg_len_test_data[i],
|
|
tag_len_test_data[i]);
|
|
|
|
if (ret != 0 ||
|
|
memcmp(ciphertext, res_test_data[i],
|
|
msg_len_test_data[i] + tag_len_test_data[i]) != 0) {
|
|
if (verbose != 0) {
|
|
mbedtls_printf("failed\n");
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
memset(plaintext, 0, CCM_SELFTEST_PT_MAX_LEN);
|
|
|
|
ret = mbedtls_ccm_auth_decrypt(&ctx, msg_len_test_data[i],
|
|
iv_test_data, iv_len_test_data[i],
|
|
ad_test_data, add_len_test_data[i],
|
|
ciphertext, plaintext,
|
|
ciphertext + msg_len_test_data[i],
|
|
tag_len_test_data[i]);
|
|
|
|
if (ret != 0 ||
|
|
memcmp(plaintext, msg_test_data, msg_len_test_data[i]) != 0) {
|
|
if (verbose != 0) {
|
|
mbedtls_printf("failed\n");
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
if (verbose != 0) {
|
|
mbedtls_printf("passed\n");
|
|
}
|
|
}
|
|
|
|
mbedtls_ccm_free(&ctx);
|
|
|
|
if (verbose != 0) {
|
|
mbedtls_printf("\n");
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
|
|
|
|
#endif /* MBEDTLS_CCM_C */
|