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Refine buffer handling in stream_decrypt

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This commit is contained in:
Max Lv
2017-02-04 16:22:58 +08:00
parent 68929513d3
commit 2b1b9bb403
1 changed files with 40 additions and 16 deletions
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src/stream.c
+40 -16
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@@ -243,6 +243,11 @@ stream_cipher_ctx_init(cipher_ctx_t *ctx, int method, int enc)
void
stream_cipher_ctx_release(cipher_ctx_t *cipher_ctx)
{
if (cipher_ctx->chunk != NULL) {
bfree(cipher_ctx->chunk);
ss_free(cipher_ctx->chunk);
cipher_ctx->chunk = NULL;
}
mbedtls_cipher_free(cipher_ctx->evp);
ss_free(cipher_ctx->evp);
}
@@ -489,22 +494,38 @@ stream_decrypt(buffer_t *ciphertext, cipher_ctx_t *cipher_ctx, size_t capacity)
static buffer_t tmp = { 0, 0, 0, NULL };
size_t nonce_len = 0;
int err = CRYPTO_OK;
int err = CRYPTO_OK;
brealloc(&tmp, ciphertext->len, capacity);
buffer_t *plaintext = &tmp;
plaintext->len = ciphertext->len;
if (!cipher_ctx->init) {
if (ciphertext->len <= cipher->nonce_len)
return CRYPTO_ERROR;
if (cipher_ctx->chunk == NULL) {
cipher_ctx->chunk = (buffer_t *)ss_malloc(sizeof(buffer_t));
memset(cipher_ctx->chunk, 0, sizeof(buffer_t));
balloc(cipher_ctx->chunk, cipher->nonce_len);
}
uint8_t *nonce = cipher_ctx->nonce;
nonce_len = cipher->nonce_len;
size_t left_len = min(cipher->nonce_len - cipher_ctx->chunk->len,
ciphertext->len);
if (left_len > 0) {
memcpy(cipher_ctx->chunk->data, ciphertext->data, left_len);
memmove(ciphertext->data, ciphertext->data + left_len,
ciphertext->len - left_len);
cipher_ctx->chunk->len += left_len;
ciphertext->len -= left_len;
}
if (cipher_ctx->chunk->len < cipher->nonce_len)
return CRYPTO_NEED_MORE;
uint8_t *nonce = cipher_ctx->nonce;
size_t nonce_len = cipher->nonce_len;
plaintext->len -= nonce_len;
memcpy(nonce, ciphertext->data, nonce_len);
memcpy(nonce, cipher_ctx->chunk->data, nonce_len);
cipher_ctx_set_nonce(cipher_ctx, nonce, nonce_len, 0);
cipher_ctx->counter = 0;
cipher_ctx->init = 1;
@@ -519,30 +540,33 @@ stream_decrypt(buffer_t *ciphertext, cipher_ctx_t *cipher_ctx, size_t capacity)
}
}
if (ciphertext->len <= 0)
return CRYPTO_NEED_MORE;
if (cipher->method >= SALSA20) {
int padding = cipher_ctx->counter % SODIUM_BLOCK_SIZE;
brealloc(plaintext, (plaintext->len + padding) * 2, capacity);
if (padding) {
brealloc(ciphertext, ciphertext->len + padding, capacity);
memmove(ciphertext->data + nonce_len + padding, ciphertext->data + nonce_len,
ciphertext->len - nonce_len);
sodium_memzero(ciphertext->data + nonce_len, padding);
memmove(ciphertext->data + padding, ciphertext->data,
ciphertext->len);
sodium_memzero(ciphertext->data, padding);
}
crypto_stream_xor_ic((uint8_t *)plaintext->data,
(const uint8_t *)(ciphertext->data + nonce_len),
(uint64_t)(ciphertext->len - nonce_len + padding),
(const uint8_t *)(ciphertext->data),
(uint64_t)(ciphertext->len + padding),
(const uint8_t *)cipher_ctx->nonce,
cipher_ctx->counter / SODIUM_BLOCK_SIZE, cipher->key,
cipher->method);
cipher_ctx->counter += ciphertext->len - nonce_len;
cipher_ctx->counter += ciphertext->len;
if (padding) {
memmove(plaintext->data, plaintext->data + padding, plaintext->len);
}
} else {
err = cipher_ctx_update(cipher_ctx, (uint8_t *)plaintext->data, &plaintext->len,
(const uint8_t *)(ciphertext->data + nonce_len),
ciphertext->len - nonce_len);
(const uint8_t *)(ciphertext->data),
ciphertext->len);
}
if (err) {
@@ -552,7 +576,7 @@ stream_decrypt(buffer_t *ciphertext, cipher_ctx_t *cipher_ctx, size_t capacity)
#ifdef DEBUG
dump("PLAIN", plaintext->data, plaintext->len);
dump("CIPHER", ciphertext->data + nonce_len, ciphertext->len - nonce_len);
dump("CIPHER", ciphertext->data, ciphertext->len);
#endif
brealloc(ciphertext, plaintext->len, capacity);