492 lines
15 KiB
C
492 lines
15 KiB
C
/**
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* \file chachapoly.c
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*
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* \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539.
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_CHACHAPOLY_C)
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#include "mbedtls/chachapoly.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/error.h"
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#include <string.h>
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#include "mbedtls/platform.h"
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#if !defined(MBEDTLS_CHACHAPOLY_ALT)
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#define CHACHAPOLY_STATE_INIT (0)
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#define CHACHAPOLY_STATE_AAD (1)
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#define CHACHAPOLY_STATE_CIPHERTEXT (2) /* Encrypting or decrypting */
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#define CHACHAPOLY_STATE_FINISHED (3)
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/**
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* \brief Adds nul bytes to pad the AAD for Poly1305.
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*
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* \param ctx The ChaCha20-Poly1305 context.
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*/
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static int chachapoly_pad_aad(mbedtls_chachapoly_context *ctx)
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{
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uint32_t partial_block_len = (uint32_t) (ctx->aad_len % 16U);
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unsigned char zeroes[15];
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if (partial_block_len == 0U) {
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return 0;
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}
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memset(zeroes, 0, sizeof(zeroes));
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return mbedtls_poly1305_update(&ctx->poly1305_ctx,
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zeroes,
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16U - partial_block_len);
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}
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/**
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* \brief Adds nul bytes to pad the ciphertext for Poly1305.
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*
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* \param ctx The ChaCha20-Poly1305 context.
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*/
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static int chachapoly_pad_ciphertext(mbedtls_chachapoly_context *ctx)
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{
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uint32_t partial_block_len = (uint32_t) (ctx->ciphertext_len % 16U);
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unsigned char zeroes[15];
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if (partial_block_len == 0U) {
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return 0;
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}
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memset(zeroes, 0, sizeof(zeroes));
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return mbedtls_poly1305_update(&ctx->poly1305_ctx,
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zeroes,
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16U - partial_block_len);
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}
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void mbedtls_chachapoly_init(mbedtls_chachapoly_context *ctx)
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{
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mbedtls_chacha20_init(&ctx->chacha20_ctx);
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mbedtls_poly1305_init(&ctx->poly1305_ctx);
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ctx->aad_len = 0U;
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ctx->ciphertext_len = 0U;
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ctx->state = CHACHAPOLY_STATE_INIT;
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ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT;
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}
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void mbedtls_chachapoly_free(mbedtls_chachapoly_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_chacha20_free(&ctx->chacha20_ctx);
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mbedtls_poly1305_free(&ctx->poly1305_ctx);
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ctx->aad_len = 0U;
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ctx->ciphertext_len = 0U;
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ctx->state = CHACHAPOLY_STATE_INIT;
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ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT;
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}
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int mbedtls_chachapoly_setkey(mbedtls_chachapoly_context *ctx,
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const unsigned char key[32])
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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ret = mbedtls_chacha20_setkey(&ctx->chacha20_ctx, key);
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return ret;
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}
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int mbedtls_chachapoly_starts(mbedtls_chachapoly_context *ctx,
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const unsigned char nonce[12],
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mbedtls_chachapoly_mode_t mode)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char poly1305_key[64];
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/* Set counter = 0, will be update to 1 when generating Poly1305 key */
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ret = mbedtls_chacha20_starts(&ctx->chacha20_ctx, nonce, 0U);
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if (ret != 0) {
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goto cleanup;
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}
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/* Generate the Poly1305 key by getting the ChaCha20 keystream output with
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* counter = 0. This is the same as encrypting a buffer of zeroes.
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* Only the first 256-bits (32 bytes) of the key is used for Poly1305.
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* The other 256 bits are discarded.
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*/
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memset(poly1305_key, 0, sizeof(poly1305_key));
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ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, sizeof(poly1305_key),
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poly1305_key, poly1305_key);
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if (ret != 0) {
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goto cleanup;
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}
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ret = mbedtls_poly1305_starts(&ctx->poly1305_ctx, poly1305_key);
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if (ret == 0) {
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ctx->aad_len = 0U;
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ctx->ciphertext_len = 0U;
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ctx->state = CHACHAPOLY_STATE_AAD;
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ctx->mode = mode;
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}
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cleanup:
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mbedtls_platform_zeroize(poly1305_key, 64U);
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return ret;
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}
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int mbedtls_chachapoly_update_aad(mbedtls_chachapoly_context *ctx,
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const unsigned char *aad,
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size_t aad_len)
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{
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if (ctx->state != CHACHAPOLY_STATE_AAD) {
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return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
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}
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ctx->aad_len += aad_len;
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return mbedtls_poly1305_update(&ctx->poly1305_ctx, aad, aad_len);
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}
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int mbedtls_chachapoly_update(mbedtls_chachapoly_context *ctx,
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size_t len,
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const unsigned char *input,
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unsigned char *output)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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if ((ctx->state != CHACHAPOLY_STATE_AAD) &&
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(ctx->state != CHACHAPOLY_STATE_CIPHERTEXT)) {
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return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
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}
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if (ctx->state == CHACHAPOLY_STATE_AAD) {
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ctx->state = CHACHAPOLY_STATE_CIPHERTEXT;
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ret = chachapoly_pad_aad(ctx);
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if (ret != 0) {
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return ret;
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}
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}
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ctx->ciphertext_len += len;
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if (ctx->mode == MBEDTLS_CHACHAPOLY_ENCRYPT) {
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ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
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if (ret != 0) {
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return ret;
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}
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ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, output, len);
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if (ret != 0) {
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return ret;
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}
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} else { /* DECRYPT */
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ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, input, len);
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if (ret != 0) {
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return ret;
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}
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ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output);
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if (ret != 0) {
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return ret;
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}
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}
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return 0;
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}
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int mbedtls_chachapoly_finish(mbedtls_chachapoly_context *ctx,
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unsigned char mac[16])
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char len_block[16];
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if (ctx->state == CHACHAPOLY_STATE_INIT) {
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return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE;
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}
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if (ctx->state == CHACHAPOLY_STATE_AAD) {
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ret = chachapoly_pad_aad(ctx);
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if (ret != 0) {
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return ret;
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}
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} else if (ctx->state == CHACHAPOLY_STATE_CIPHERTEXT) {
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ret = chachapoly_pad_ciphertext(ctx);
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if (ret != 0) {
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return ret;
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}
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}
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ctx->state = CHACHAPOLY_STATE_FINISHED;
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/* The lengths of the AAD and ciphertext are processed by
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* Poly1305 as the final 128-bit block, encoded as little-endian integers.
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*/
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MBEDTLS_PUT_UINT64_LE(ctx->aad_len, len_block, 0);
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MBEDTLS_PUT_UINT64_LE(ctx->ciphertext_len, len_block, 8);
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ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, len_block, 16U);
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if (ret != 0) {
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return ret;
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}
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ret = mbedtls_poly1305_finish(&ctx->poly1305_ctx, mac);
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return ret;
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}
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static int chachapoly_crypt_and_tag(mbedtls_chachapoly_context *ctx,
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mbedtls_chachapoly_mode_t mode,
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size_t length,
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const unsigned char nonce[12],
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const unsigned char *aad,
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size_t aad_len,
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const unsigned char *input,
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unsigned char *output,
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unsigned char tag[16])
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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ret = mbedtls_chachapoly_starts(ctx, nonce, mode);
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if (ret != 0) {
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goto cleanup;
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}
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ret = mbedtls_chachapoly_update_aad(ctx, aad, aad_len);
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if (ret != 0) {
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goto cleanup;
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}
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ret = mbedtls_chachapoly_update(ctx, length, input, output);
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if (ret != 0) {
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goto cleanup;
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}
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ret = mbedtls_chachapoly_finish(ctx, tag);
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cleanup:
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return ret;
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}
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int mbedtls_chachapoly_encrypt_and_tag(mbedtls_chachapoly_context *ctx,
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size_t length,
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const unsigned char nonce[12],
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const unsigned char *aad,
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size_t aad_len,
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const unsigned char *input,
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unsigned char *output,
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unsigned char tag[16])
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{
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return chachapoly_crypt_and_tag(ctx, MBEDTLS_CHACHAPOLY_ENCRYPT,
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length, nonce, aad, aad_len,
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input, output, tag);
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}
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int mbedtls_chachapoly_auth_decrypt(mbedtls_chachapoly_context *ctx,
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size_t length,
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const unsigned char nonce[12],
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const unsigned char *aad,
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size_t aad_len,
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const unsigned char tag[16],
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const unsigned char *input,
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unsigned char *output)
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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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size_t i;
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int diff;
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if ((ret = chachapoly_crypt_and_tag(ctx,
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MBEDTLS_CHACHAPOLY_DECRYPT, length, nonce,
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aad, aad_len, input, output, check_tag)) != 0) {
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return ret;
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}
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/* Check tag in "constant-time" */
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for (diff = 0, i = 0; i < sizeof(check_tag); i++) {
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diff |= tag[i] ^ check_tag[i];
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}
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if (diff != 0) {
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mbedtls_platform_zeroize(output, length);
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return MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED;
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}
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return 0;
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}
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#endif /* MBEDTLS_CHACHAPOLY_ALT */
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#if defined(MBEDTLS_SELF_TEST)
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static const unsigned char test_key[1][32] =
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{
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{
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0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
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0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
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0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
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0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
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}
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};
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static const unsigned char test_nonce[1][12] =
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{
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{
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0x07, 0x00, 0x00, 0x00, /* 32-bit common part */
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0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 /* 64-bit IV */
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}
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};
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static const unsigned char test_aad[1][12] =
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{
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{
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0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3,
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0xc4, 0xc5, 0xc6, 0xc7
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}
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};
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static const size_t test_aad_len[1] =
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{
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12U
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};
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static const unsigned char test_input[1][114] =
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{
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{
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0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61,
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0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e, 0x74, 0x6c,
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0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20,
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0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x61, 0x73,
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0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39,
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0x3a, 0x20, 0x49, 0x66, 0x20, 0x49, 0x20, 0x63,
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0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66,
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0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f,
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0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e, 0x65, 0x20,
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0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20,
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0x74, 0x68, 0x65, 0x20, 0x66, 0x75, 0x74, 0x75,
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0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73,
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0x63, 0x72, 0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f,
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0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69,
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0x74, 0x2e
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}
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};
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static const unsigned char test_output[1][114] =
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{
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{
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0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb,
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0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef, 0x7e, 0xc2,
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0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe,
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0xa9, 0xe2, 0xb5, 0xa7, 0x36, 0xee, 0x62, 0xd6,
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0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12,
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0x82, 0xfa, 0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b,
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0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29,
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0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36,
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0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77, 0x8b, 0x8c,
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0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58,
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0xfa, 0xb3, 0x24, 0xe4, 0xfa, 0xd6, 0x75, 0x94,
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0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc,
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0x3f, 0xf4, 0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d,
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0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
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0x61, 0x16
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}
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};
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static const size_t test_input_len[1] =
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{
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114U
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};
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static const unsigned char test_mac[1][16] =
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{
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{
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0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a,
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0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60, 0x06, 0x91
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}
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};
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/* Make sure no other definition is already present. */
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#undef ASSERT
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#define ASSERT(cond, args) \
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do \
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{ \
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if (!(cond)) \
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{ \
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if (verbose != 0) \
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mbedtls_printf args; \
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\
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return -1; \
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} \
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} \
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while (0)
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int mbedtls_chachapoly_self_test(int verbose)
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{
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mbedtls_chachapoly_context ctx;
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unsigned i;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char output[200];
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unsigned char mac[16];
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for (i = 0U; i < 1U; i++) {
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if (verbose != 0) {
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mbedtls_printf(" ChaCha20-Poly1305 test %u ", i);
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}
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mbedtls_chachapoly_init(&ctx);
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ret = mbedtls_chachapoly_setkey(&ctx, test_key[i]);
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ASSERT(0 == ret, ("setkey() error code: %i\n", ret));
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ret = mbedtls_chachapoly_encrypt_and_tag(&ctx,
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test_input_len[i],
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test_nonce[i],
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test_aad[i],
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test_aad_len[i],
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test_input[i],
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output,
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mac);
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ASSERT(0 == ret, ("crypt_and_tag() error code: %i\n", ret));
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ASSERT(0 == memcmp(output, test_output[i], test_input_len[i]),
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("failure (wrong output)\n"));
|
|
|
|
ASSERT(0 == memcmp(mac, test_mac[i], 16U),
|
|
("failure (wrong MAC)\n"));
|
|
|
|
mbedtls_chachapoly_free(&ctx);
|
|
|
|
if (verbose != 0) {
|
|
mbedtls_printf("passed\n");
|
|
}
|
|
}
|
|
|
|
if (verbose != 0) {
|
|
mbedtls_printf("\n");
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif /* MBEDTLS_SELF_TEST */
|
|
|
|
#endif /* MBEDTLS_CHACHAPOLY_C */
|