static int pkey_hmac_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src) {
HMAC_PKEY_CTX *sctx, *dctx;
if (!pkey_hmac_init(dst)) {
return 0;
}
sctx = src->data;
dctx = dst->data;
dctx->md = sctx->md;
HMAC_CTX_init(&dctx->ctx);
if (!HMAC_CTX_copy_ex(&dctx->ctx, &sctx->ctx)) {
return 0;
}
if (sctx->ktmp.data) {
if (!ASN1_OCTET_STRING_set(&dctx->ktmp, sctx->ktmp.data,
sctx->ktmp.length)) {
return 0;
}
}
return 1;
}
static int aead_tls_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
size_t *out_len, size_t max_out_len,
const uint8_t *nonce, size_t nonce_len,
const uint8_t *in, size_t in_len,
const uint8_t *ad, size_t ad_len) {
AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX *)ctx->aead_state;
if (tls_ctx->cipher_ctx.encrypt) {
/* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_INVALID_OPERATION);
return 0;
}
if (in_len < HMAC_size(&tls_ctx->hmac_ctx)) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
if (max_out_len < in_len) {
/* This requires that the caller provide space for the MAC, even though it
* will always be removed on return. */
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_BUFFER_TOO_SMALL);
return 0;
}
if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_INVALID_NONCE_SIZE);
return 0;
}
if (ad_len != 13 - 2 /* length bytes */) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_INVALID_AD_SIZE);
return 0;
}
if (in_len > INT_MAX) {
/* EVP_CIPHER takes int as input. */
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_TOO_LARGE);
return 0;
}
/* Configure the explicit IV. */
if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
!tls_ctx->implicit_iv &&
!EVP_DecryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
return 0;
}
/* Decrypt to get the plaintext + MAC + padding. */
size_t total = 0;
int len;
if (!EVP_DecryptUpdate(&tls_ctx->cipher_ctx, out, &len, in, (int)in_len)) {
return 0;
}
total += len;
if (!EVP_DecryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
return 0;
}
total += len;
assert(total == in_len);
/* Remove CBC padding. Code from here on is timing-sensitive with respect to
* |padding_ok| and |data_plus_mac_len| for CBC ciphers. */
int padding_ok;
unsigned data_plus_mac_len, data_len;
if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE) {
padding_ok = EVP_tls_cbc_remove_padding(
&data_plus_mac_len, out, total,
EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx),
(unsigned)HMAC_size(&tls_ctx->hmac_ctx));
/* Publicly invalid. This can be rejected in non-constant time. */
if (padding_ok == 0) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
} else {
padding_ok = 1;
data_plus_mac_len = total;
/* |data_plus_mac_len| = |total| = |in_len| at this point. |in_len| has
* already been checked against the MAC size at the top of the function. */
assert(data_plus_mac_len >= HMAC_size(&tls_ctx->hmac_ctx));
}
data_len = data_plus_mac_len - HMAC_size(&tls_ctx->hmac_ctx);
/* At this point, |padding_ok| is 1 or -1. If 1, the padding is valid and the
* first |data_plus_mac_size| bytes after |out| are the plaintext and
* MAC. Either way, |data_plus_mac_size| is large enough to extract a MAC. */
/* To allow for CBC mode which changes cipher length, |ad| doesn't include the
* length for legacy ciphers. */
uint8_t ad_fixed[13];
memcpy(ad_fixed, ad, 11);
ad_fixed[11] = (uint8_t)(data_len >> 8);
ad_fixed[12] = (uint8_t)(data_len & 0xff);
ad_len += 2;
/* Compute the MAC and extract the one in the record. */
uint8_t mac[EVP_MAX_MD_SIZE];
size_t mac_len;
uint8_t record_mac_tmp[EVP_MAX_MD_SIZE];
uint8_t *record_mac;
if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
EVP_tls_cbc_record_digest_supported(tls_ctx->hmac_ctx.md)) {
if (!EVP_tls_cbc_digest_record(tls_ctx->hmac_ctx.md, mac, &mac_len,
ad_fixed, out, data_plus_mac_len, total,
tls_ctx->mac_key, tls_ctx->mac_key_len)) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));
record_mac = record_mac_tmp;
EVP_tls_cbc_copy_mac(record_mac, mac_len, out, data_plus_mac_len, total);
} else {
/* We should support the constant-time path for all CBC-mode ciphers
* implemented. */
assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) != EVP_CIPH_CBC_MODE);
HMAC_CTX hmac_ctx;
HMAC_CTX_init(&hmac_ctx);
unsigned mac_len_u;
if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) ||
!HMAC_Update(&hmac_ctx, ad_fixed, ad_len) ||
!HMAC_Update(&hmac_ctx, out, data_len) ||
!HMAC_Final(&hmac_ctx, mac, &mac_len_u)) {
HMAC_CTX_cleanup(&hmac_ctx);
return 0;
}
mac_len = mac_len_u;
HMAC_CTX_cleanup(&hmac_ctx);
assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));
record_mac = &out[data_len];
}
/* Perform the MAC check and the padding check in constant-time. It should be
* safe to simply perform the padding check first, but it would not be under a
* different choice of MAC location on padding failure. See
* EVP_tls_cbc_remove_padding. */
unsigned good = constant_time_eq_int(CRYPTO_memcmp(record_mac, mac, mac_len),
0);
good &= constant_time_eq_int(padding_ok, 1);
if (!good) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
/* End of timing-sensitive code. */
*out_len = data_len;
return 1;
}
static int aead_tls_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
size_t *out_len, size_t max_out_len,
const uint8_t *nonce, size_t nonce_len,
const uint8_t *in, size_t in_len,
const uint8_t *ad, size_t ad_len) {
AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX *)ctx->aead_state;
size_t total = 0;
if (!tls_ctx->cipher_ctx.encrypt) {
/* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
OPENSSL_PUT_ERROR(CIPHER, aead_tls_seal, CIPHER_R_INVALID_OPERATION);
return 0;
}
if (in_len + EVP_AEAD_max_overhead(ctx->aead) < in_len ||
in_len > INT_MAX) {
/* EVP_CIPHER takes int as input. */
OPENSSL_PUT_ERROR(CIPHER, aead_tls_seal, CIPHER_R_TOO_LARGE);
return 0;
}
if (max_out_len < in_len + EVP_AEAD_max_overhead(ctx->aead)) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_seal, CIPHER_R_BUFFER_TOO_SMALL);
return 0;
}
if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_seal, CIPHER_R_INVALID_NONCE_SIZE);
return 0;
}
if (ad_len != 13 - 2 /* length bytes */) {
OPENSSL_PUT_ERROR(CIPHER, aead_tls_seal, CIPHER_R_INVALID_AD_SIZE);
return 0;
}
/* To allow for CBC mode which changes cipher length, |ad| doesn't include the
* length for legacy ciphers. */
uint8_t ad_extra[2];
ad_extra[0] = (uint8_t)(in_len >> 8);
ad_extra[1] = (uint8_t)(in_len & 0xff);
/* Compute the MAC. This must be first in case the operation is being done
* in-place. */
uint8_t mac[EVP_MAX_MD_SIZE];
unsigned mac_len;
HMAC_CTX hmac_ctx;
HMAC_CTX_init(&hmac_ctx);
if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) ||
!HMAC_Update(&hmac_ctx, ad, ad_len) ||
!HMAC_Update(&hmac_ctx, ad_extra, sizeof(ad_extra)) ||
!HMAC_Update(&hmac_ctx, in, in_len) ||
!HMAC_Final(&hmac_ctx, mac, &mac_len)) {
HMAC_CTX_cleanup(&hmac_ctx);
return 0;
}
HMAC_CTX_cleanup(&hmac_ctx);
/* Configure the explicit IV. */
if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
!tls_ctx->implicit_iv &&
!EVP_EncryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
return 0;
}
/* Encrypt the input. */
int len;
if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out, &len, in,
(int)in_len)) {
return 0;
}
total = len;
/* Feed the MAC into the cipher. */
if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, mac,
(int)mac_len)) {
return 0;
}
total += len;
unsigned block_size = EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx);
if (block_size > 1) {
assert(block_size <= 256);
assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE);
/* Compute padding and feed that into the cipher. */
uint8_t padding[256];
unsigned padding_len = block_size - ((in_len + mac_len) % block_size);
memset(padding, padding_len - 1, padding_len);
if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, padding,
(int)padding_len)) {
return 0;
}
total += len;
}
if (!EVP_EncryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
return 0;
}
total += len;
*out_len = total;
return 1;
}
/* tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246,
* section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and
* |secret| as the secret. |seed1| through |seed3| are concatenated to form the
* seed parameter. It returns one on success and zero on failure. */
static int tls1_P_hash(uint8_t *out, size_t out_len, const EVP_MD *md,
const uint8_t *secret, size_t secret_len,
const uint8_t *seed1, size_t seed1_len,
const uint8_t *seed2, size_t seed2_len,
const uint8_t *seed3, size_t seed3_len) {
size_t chunk;
HMAC_CTX ctx, ctx_tmp, ctx_init;
uint8_t A1[EVP_MAX_MD_SIZE];
unsigned A1_len;
int ret = 0;
chunk = EVP_MD_size(md);
HMAC_CTX_init(&ctx);
HMAC_CTX_init(&ctx_tmp);
HMAC_CTX_init(&ctx_init);
if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) ||
!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
(seed1_len && !HMAC_Update(&ctx, seed1, seed1_len)) ||
(seed2_len && !HMAC_Update(&ctx, seed2, seed2_len)) ||
(seed3_len && !HMAC_Update(&ctx, seed3, seed3_len)) ||
!HMAC_Final(&ctx, A1, &A1_len)) {
goto err;
}
for (;;) {
/* Reinit mac contexts. */
if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
!HMAC_Update(&ctx, A1, A1_len) ||
(out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) ||
(seed1_len && !HMAC_Update(&ctx, seed1, seed1_len)) ||
(seed2_len && !HMAC_Update(&ctx, seed2, seed2_len)) ||
(seed3_len && !HMAC_Update(&ctx, seed3, seed3_len))) {
goto err;
}
unsigned len;
uint8_t hmac[EVP_MAX_MD_SIZE];
if (!HMAC_Final(&ctx, hmac, &len)) {
goto err;
}
assert(len == chunk);
/* XOR the result into |out|. */
if (len > out_len) {
len = out_len;
}
unsigned i;
for (i = 0; i < len; i++) {
out[i] ^= hmac[i];
}
out += len;
out_len -= len;
if (out_len == 0) {
break;
}
/* Calculate the next A1 value. */
if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) {
goto err;
}
}
ret = 1;
err:
HMAC_CTX_cleanup(&ctx);
HMAC_CTX_cleanup(&ctx_tmp);
HMAC_CTX_cleanup(&ctx_init);
OPENSSL_cleanse(A1, sizeof(A1));
return ret;
}
int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src) {
HMAC_CTX_init(dest);
return HMAC_CTX_copy_ex(dest, src);
}
/* tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246,
* section 5. It writes |out_len| bytes to |out|, using |md| as the hash and
* |secret| as the secret. |seed1| through |seed3| are concatenated to form the
* seed parameter. It returns one on success and zero on failure. */
static int tls1_P_hash(uint8_t *out, size_t out_len, const EVP_MD *md,
const uint8_t *secret, size_t secret_len,
const uint8_t *seed1, size_t seed1_len,
const uint8_t *seed2, size_t seed2_len,
const uint8_t *seed3, size_t seed3_len) {
size_t chunk;
HMAC_CTX ctx, ctx_tmp, ctx_init;
uint8_t A1[EVP_MAX_MD_SIZE];
unsigned A1_len;
int ret = 0;
chunk = EVP_MD_size(md);
HMAC_CTX_init(&ctx);
HMAC_CTX_init(&ctx_tmp);
HMAC_CTX_init(&ctx_init);
if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) ||
!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
(seed1_len && !HMAC_Update(&ctx, seed1, seed1_len)) ||
(seed2_len && !HMAC_Update(&ctx, seed2, seed2_len)) ||
(seed3_len && !HMAC_Update(&ctx, seed3, seed3_len)) ||
!HMAC_Final(&ctx, A1, &A1_len)) {
goto err;
}
for (;;) {
/* Reinit mac contexts. */
if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
!HMAC_Update(&ctx, A1, A1_len) ||
(out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) ||
(seed1_len && !HMAC_Update(&ctx, seed1, seed1_len)) ||
(seed2_len && !HMAC_Update(&ctx, seed2, seed2_len)) ||
(seed3_len && !HMAC_Update(&ctx, seed3, seed3_len))) {
goto err;
}
if (out_len > chunk) {
unsigned len;
if (!HMAC_Final(&ctx, out, &len)) {
goto err;
}
assert(len == chunk);
out += len;
out_len -= len;
/* Calculate the next A1 value. */
if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) {
goto err;
}
} else {
/* Last chunk. */
if (!HMAC_Final(&ctx, A1, &A1_len)) {
goto err;
}
memcpy(out, A1, out_len);
break;
}
}
ret = 1;
err:
HMAC_CTX_cleanup(&ctx);
HMAC_CTX_cleanup(&ctx_tmp);
HMAC_CTX_cleanup(&ctx_init);
OPENSSL_cleanse(A1, sizeof(A1));
return ret;
}
// tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246,
// section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and
// |secret| as the secret. |label|, |seed1|, and |seed2| are concatenated to
// form the seed parameter. It returns true on success and false on failure.
static int tls1_P_hash(uint8_t *out, size_t out_len,
const EVP_MD *md,
const uint8_t *secret, size_t secret_len,
const char *label, size_t label_len,
const uint8_t *seed1, size_t seed1_len,
const uint8_t *seed2, size_t seed2_len) {
HMAC_CTX ctx, ctx_tmp, ctx_init;
uint8_t A1[EVP_MAX_MD_SIZE];
unsigned A1_len;
int ret = 0;
const size_t chunk = EVP_MD_size(md);
HMAC_CTX_init(&ctx);
HMAC_CTX_init(&ctx_tmp);
HMAC_CTX_init(&ctx_init);
if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) ||
!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
!HMAC_Update(&ctx, (const uint8_t *) label, label_len) ||
!HMAC_Update(&ctx, seed1, seed1_len) ||
!HMAC_Update(&ctx, seed2, seed2_len) ||
!HMAC_Final(&ctx, A1, &A1_len)) {
goto err;
}
for (;;) {
unsigned len;
uint8_t hmac[EVP_MAX_MD_SIZE];
if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
!HMAC_Update(&ctx, A1, A1_len) ||
// Save a copy of |ctx| to compute the next A1 value below.
(out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) ||
!HMAC_Update(&ctx, (const uint8_t *) label, label_len) ||
!HMAC_Update(&ctx, seed1, seed1_len) ||
!HMAC_Update(&ctx, seed2, seed2_len) ||
!HMAC_Final(&ctx, hmac, &len)) {
goto err;
}
assert(len == chunk);
// XOR the result into |out|.
if (len > out_len) {
len = out_len;
}
for (unsigned i = 0; i < len; i++) {
out[i] ^= hmac[i];
}
out += len;
out_len -= len;
if (out_len == 0) {
break;
}
// Calculate the next A1 value.
if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) {
goto err;
}
}
ret = 1;
err:
OPENSSL_cleanse(A1, sizeof(A1));
HMAC_CTX_cleanup(&ctx);
HMAC_CTX_cleanup(&ctx_tmp);
HMAC_CTX_cleanup(&ctx_init);
return ret;
}
