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openssl/ssl/tls13_enc.c
Joseph Birr-Pixton b0c9fc9b48 TLS1.3: Correct intermediate secret derivation 
This label for this derivation was incorrectly "derived" or "der" depending
on the pointer size of the build(!). The correct string is "derived secret".

(cherry picked from commit 936dcf272033c1bf59a5e859ec63e2557194f191)

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2989)
2017-03-19 20:59:59 +00:00

607 lines
21 KiB
C
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/*
* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdlib.h>
#include "ssl_locl.h"
#include <openssl/evp.h>
#include <openssl/kdf.h>
#define TLS13_MAX_LABEL_LEN 246
/* Always filled with zeros */
static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
/*
* Given a |secret|; a |label| of length |labellen|; and a |hash| of the
* handshake messages, derive a new secret |outlen| bytes long and store it in
* the location pointed to be |out|. The |hash| value may be NULL. Returns 1 on
* success 0 on failure.
*/
int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
const unsigned char *label, size_t labellen,
const unsigned char *hash,
unsigned char *out, size_t outlen)
{
const unsigned char label_prefix[] = "TLS 1.3, ";
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
int ret;
size_t hkdflabellen;
size_t hashlen;
/*
* 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
* prefix and label + bytes for the label itself + bytes for the hash
*/
unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
+ EVP_MAX_MD_SIZE];
WPACKET pkt;
if (pctx == NULL)
return 0;
hashlen = EVP_MD_size(md);
if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
|| !WPACKET_put_bytes_u16(&pkt, outlen)
|| !WPACKET_start_sub_packet_u8(&pkt)
|| !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_close(&pkt)
|| !WPACKET_sub_memcpy_u8(&pkt, hash, (hash == NULL) ? 0 : hashlen)
|| !WPACKET_get_total_written(&pkt, &hkdflabellen)
|| !WPACKET_finish(&pkt)) {
EVP_PKEY_CTX_free(pctx);
WPACKET_cleanup(&pkt);
return 0;
}
ret = EVP_PKEY_derive_init(pctx) <= 0
|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
<= 0
|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
|| EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
|| EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
|| EVP_PKEY_derive(pctx, out, &outlen) <= 0;
EVP_PKEY_CTX_free(pctx);
return ret == 0;
}
/*
* Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
* success 0 on failure.
*/
int tls13_derive_key(SSL *s, const EVP_MD *md, const unsigned char *secret,
unsigned char *key, size_t keylen)
{
static const unsigned char keylabel[] = "key";
return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
NULL, key, keylen);
}
/*
* Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
* success 0 on failure.
*/
int tls13_derive_iv(SSL *s, const EVP_MD *md, const unsigned char *secret,
unsigned char *iv, size_t ivlen)
{
static const unsigned char ivlabel[] = "iv";
return tls13_hkdf_expand(s, md, secret, ivlabel, sizeof(ivlabel) - 1,
NULL, iv, ivlen);
}
int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
const unsigned char *secret,
unsigned char *fin, size_t finlen)
{
static const unsigned char finishedlabel[] = "finished";
return tls13_hkdf_expand(s, md, secret, finishedlabel,
sizeof(finishedlabel) - 1, NULL, fin, finlen);
}
/*
* Given the previous secret |prevsecret| and a new input secret |insecret| of
* length |insecretlen|, generate a new secret and store it in the location
* pointed to by |outsecret|. Returns 1 on success 0 on failure.
*/
int tls13_generate_secret(SSL *s, const EVP_MD *md,
const unsigned char *prevsecret,
const unsigned char *insecret,
size_t insecretlen,
unsigned char *outsecret)
{
size_t mdlen, prevsecretlen;
int ret;
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
static const char derived_secret_label[] = "derived secret";
unsigned char preextractsec[EVP_MAX_MD_SIZE];
if (pctx == NULL)
return 0;
mdlen = EVP_MD_size(md);
if (insecret == NULL) {
insecret = default_zeros;
insecretlen = mdlen;
}
if (prevsecret == NULL) {
prevsecret = default_zeros;
prevsecretlen = 0;
} else {
EVP_MD_CTX *mctx = EVP_MD_CTX_new();
unsigned char hash[EVP_MAX_MD_SIZE];
/* The pre-extract derive step uses a hash of no messages */
if (mctx == NULL
|| EVP_DigestInit_ex(mctx, md, NULL) <= 0
|| EVP_DigestFinal_ex(mctx, hash, NULL) <= 0) {
EVP_MD_CTX_free(mctx);
return 0;
}
EVP_MD_CTX_free(mctx);
/* Generate the pre-extract secret */
if (!tls13_hkdf_expand(s, md, prevsecret,
(unsigned char *)derived_secret_label,
sizeof(derived_secret_label) - 1, hash,
preextractsec, mdlen))
return 0;
prevsecret = preextractsec;
prevsecretlen = mdlen;
}
ret = EVP_PKEY_derive_init(pctx) <= 0
|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
<= 0
|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
|| EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
|| EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
<= 0
|| EVP_PKEY_derive(pctx, outsecret, &mdlen)
<= 0;
EVP_PKEY_CTX_free(pctx);
if (prevsecret == preextractsec)
OPENSSL_cleanse(preextractsec, mdlen);
return ret == 0;
}
/*
* Given an input secret |insecret| of length |insecretlen| generate the
* handshake secret. This requires the early secret to already have been
* generated. Returns 1 on success 0 on failure.
*/
int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
size_t insecretlen)
{
return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
insecret, insecretlen,
(unsigned char *)&s->handshake_secret);
}
/*
* Given the handshake secret |prev| of length |prevlen| generate the master
* secret and store its length in |*secret_size|. Returns 1 on success 0 on
* failure.
*/
int tls13_generate_master_secret(SSL *s, unsigned char *out,
unsigned char *prev, size_t prevlen,
size_t *secret_size)
{
const EVP_MD *md = ssl_handshake_md(s);
*secret_size = EVP_MD_size(md);
return tls13_generate_secret(s, md, prev, NULL, 0, out);
}
/*
* Generates the mac for the Finished message. Returns the length of the MAC or
* 0 on error.
*/
size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
unsigned char *out)
{
const EVP_MD *md = ssl_handshake_md(s);
unsigned char hash[EVP_MAX_MD_SIZE];
size_t hashlen, ret = 0;
EVP_PKEY *key = NULL;
EVP_MD_CTX *ctx = EVP_MD_CTX_new();
if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
goto err;
if (str == s->method->ssl3_enc->server_finished_label)
key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
s->server_finished_secret, hashlen);
else
key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
s->client_finished_secret, hashlen);
if (key == NULL
|| ctx == NULL
|| EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
|| EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
|| EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
goto err;
ret = hashlen;
err:
EVP_PKEY_free(key);
EVP_MD_CTX_free(ctx);
return ret;
}
/*
* There isn't really a key block in TLSv1.3, but we still need this function
* for initialising the cipher and hash. Returns 1 on success or 0 on failure.
*/
int tls13_setup_key_block(SSL *s)
{
const EVP_CIPHER *c;
const EVP_MD *hash;
int mac_type = NID_undef;
s->session->cipher = s->s3->tmp.new_cipher;
if (!ssl_cipher_get_evp
(s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
return 0;
}
s->s3->tmp.new_sym_enc = c;
s->s3->tmp.new_hash = hash;
return 1;
}
static int derive_secret_key_and_iv(SSL *s, int send, const EVP_MD *md,
const EVP_CIPHER *ciph,
const unsigned char *insecret,
const unsigned char *hash,
const unsigned char *label,
size_t labellen, unsigned char *secret,
unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
{
unsigned char key[EVP_MAX_KEY_LENGTH];
size_t ivlen, keylen, taglen;
size_t hashlen = EVP_MD_size(md);
if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, secret,
hashlen)) {
SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
goto err;
}
/* TODO(size_t): convert me */
keylen = EVP_CIPHER_key_length(ciph);
if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
uint32_t algenc;
ivlen = EVP_CCM_TLS_IV_LEN;
if (s->s3->tmp.new_cipher == NULL) {
/* We've not selected a cipher yet - we must be doing early data */
algenc = s->session->cipher->algorithm_enc;
} else {
algenc = s->s3->tmp.new_cipher->algorithm_enc;
}
if (algenc & (SSL_AES128CCM8 | SSL_AES256CCM8))
taglen = EVP_CCM8_TLS_TAG_LEN;
else
taglen = EVP_CCM_TLS_TAG_LEN;
} else {
ivlen = EVP_CIPHER_iv_length(ciph);
taglen = 0;
}
if (!tls13_derive_key(s, md, secret, key, keylen)
|| !tls13_derive_iv(s, md, secret, iv, ivlen)) {
SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
goto err;
}
if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, send) <= 0
|| !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
|| (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
taglen, NULL))
|| EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_EVP_LIB);
goto err;
}
#ifdef OPENSSL_SSL_TRACE_CRYPTO
if (s->msg_callback) {
int wh = send ? TLS1_RT_CRYPTO_WRITE : 0;
if (ciph->key_len)
s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
key, ciph->key_len, s, s->msg_callback_arg);
wh |= TLS1_RT_CRYPTO_IV;
s->msg_callback(2, s->version, wh, iv, ivlen, s,
s->msg_callback_arg);
}
#endif
return 1;
err:
OPENSSL_cleanse(key, sizeof(key));
return 0;
}
int tls13_change_cipher_state(SSL *s, int which)
{
static const unsigned char client_early_traffic[] =
"client early traffic secret";
static const unsigned char client_handshake_traffic[] =
"client handshake traffic secret";
static const unsigned char client_application_traffic[] =
"client application traffic secret";
static const unsigned char server_handshake_traffic[] =
"server handshake traffic secret";
static const unsigned char server_application_traffic[] =
"server application traffic secret";
static const unsigned char resumption_master_secret[] =
"resumption master secret";
unsigned char *iv;
unsigned char secret[EVP_MAX_MD_SIZE];
unsigned char hashval[EVP_MAX_MD_SIZE];
unsigned char *hash = hashval;
unsigned char *insecret;
unsigned char *finsecret = NULL;
const char *log_label = NULL;
EVP_CIPHER_CTX *ciph_ctx;
size_t finsecretlen = 0;
const unsigned char *label;
size_t labellen, hashlen = 0;
int ret = 0;
const EVP_MD *md = NULL;
const EVP_CIPHER *cipher = NULL;
if (which & SSL3_CC_READ) {
if (s->enc_read_ctx != NULL) {
EVP_CIPHER_CTX_reset(s->enc_read_ctx);
} else {
s->enc_read_ctx = EVP_CIPHER_CTX_new();
if (s->enc_read_ctx == NULL) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
goto err;
}
}
ciph_ctx = s->enc_read_ctx;
iv = s->read_iv;
RECORD_LAYER_reset_read_sequence(&s->rlayer);
} else {
if (s->enc_write_ctx != NULL) {
EVP_CIPHER_CTX_reset(s->enc_write_ctx);
} else {
s->enc_write_ctx = EVP_CIPHER_CTX_new();
if (s->enc_write_ctx == NULL) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
goto err;
}
}
ciph_ctx = s->enc_write_ctx;
iv = s->write_iv;
RECORD_LAYER_reset_write_sequence(&s->rlayer);
}
if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
|| ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
if (which & SSL3_CC_EARLY) {
EVP_MD_CTX *mdctx = NULL;
long handlen;
void *hdata;
unsigned int hashlenui;
const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
insecret = s->early_secret;
label = client_early_traffic;
labellen = sizeof(client_early_traffic) - 1;
log_label = CLIENT_EARLY_LABEL;
handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
if (handlen <= 0) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE,
SSL_R_BAD_HANDSHAKE_LENGTH);
goto err;
}
if (sslcipher == NULL) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
}
/*
* We need to calculate the handshake digest using the digest from
* the session. We haven't yet selected our ciphersuite so we can't
* use ssl_handshake_md().
*/
mdctx = EVP_MD_CTX_new();
if (mdctx == NULL) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
goto err;
}
cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
md = ssl_md(sslcipher->algorithm2);
if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
|| !EVP_DigestUpdate(mdctx, hdata, handlen)
|| !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
EVP_MD_CTX_free(mdctx);
goto err;
}
hashlen = hashlenui;
EVP_MD_CTX_free(mdctx);
} else if (which & SSL3_CC_HANDSHAKE) {
insecret = s->handshake_secret;
finsecret = s->client_finished_secret;
finsecretlen = EVP_MD_size(ssl_handshake_md(s));
label = client_handshake_traffic;
labellen = sizeof(client_handshake_traffic) - 1;
log_label = CLIENT_HANDSHAKE_LABEL;
/*
* The hanshake hash used for the server read/client write handshake
* traffic secret is the same as the hash for the server
* write/client read handshake traffic secret. However, if we
* processed early data then we delay changing the server
* read/client write cipher state until later, and the handshake
* hashes have moved on. Therefore we use the value saved earlier
* when we did the server write/client read change cipher state.
*/
hash = s->handshake_traffic_hash;
} else {
insecret = s->master_secret;
label = client_application_traffic;
labellen = sizeof(client_application_traffic) - 1;
log_label = CLIENT_APPLICATION_LABEL;
/*
* For this we only use the handshake hashes up until the server
* Finished hash. We do not include the client's Finished, which is
* what ssl_handshake_hash() would give us. Instead we use the
* previously saved value.
*/
hash = s->server_finished_hash;
}
} else {
/* Early data never applies to client-read/server-write */
if (which & SSL3_CC_HANDSHAKE) {
insecret = s->handshake_secret;
finsecret = s->server_finished_secret;
finsecretlen = EVP_MD_size(ssl_handshake_md(s));
label = server_handshake_traffic;
labellen = sizeof(server_handshake_traffic) - 1;
log_label = SERVER_HANDSHAKE_LABEL;
} else {
insecret = s->master_secret;
label = server_application_traffic;
labellen = sizeof(server_application_traffic) - 1;
log_label = SERVER_APPLICATION_LABEL;
}
}
if (!(which & SSL3_CC_EARLY)) {
md = ssl_handshake_md(s);
cipher = s->s3->tmp.new_sym_enc;
if (!ssl3_digest_cached_records(s, 1)
|| !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
}
}
/*
* Save the hash of handshakes up to now for use when we calculate the
* client application traffic secret
*/
if (label == server_application_traffic)
memcpy(s->server_finished_hash, hashval, hashlen);
if (label == server_handshake_traffic)
memcpy(s->handshake_traffic_hash, hashval, hashlen);
if (label == client_application_traffic) {
/*
* We also create the resumption master secret, but this time use the
* hash for the whole handshake including the Client Finished
*/
if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
resumption_master_secret,
sizeof(resumption_master_secret) - 1,
hashval, s->session->master_key, hashlen)) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
}
s->session->master_key_length = hashlen;
}
if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
insecret, hash, label, labellen, secret, iv,
ciph_ctx)) {
goto err;
}
if (label == server_application_traffic)
memcpy(s->server_app_traffic_secret, secret, hashlen);
else if (label == client_application_traffic)
memcpy(s->client_app_traffic_secret, secret, hashlen);
if (!ssl_log_secret(s, log_label, secret, hashlen)) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
}
if (finsecret != NULL
&& !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
finsecret, finsecretlen)) {
SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
}
ret = 1;
err:
OPENSSL_cleanse(secret, sizeof(secret));
return ret;
}
int tls13_update_key(SSL *s, int send)
{
static const unsigned char application_traffic[] =
"application traffic secret";
const EVP_MD *md = ssl_handshake_md(s);
size_t hashlen = EVP_MD_size(md);
unsigned char *insecret, *iv;
unsigned char secret[EVP_MAX_MD_SIZE];
EVP_CIPHER_CTX *ciph_ctx;
int ret = 0;
if (s->server == send)
insecret = s->server_app_traffic_secret;
else
insecret = s->client_app_traffic_secret;
if (send) {
iv = s->write_iv;
ciph_ctx = s->enc_write_ctx;
RECORD_LAYER_reset_write_sequence(&s->rlayer);
} else {
iv = s->read_iv;
ciph_ctx = s->enc_read_ctx;
RECORD_LAYER_reset_read_sequence(&s->rlayer);
}
if (!derive_secret_key_and_iv(s, send, ssl_handshake_md(s),
s->s3->tmp.new_sym_enc, insecret, NULL,
application_traffic,
sizeof(application_traffic) - 1, secret, iv,
ciph_ctx))
goto err;
memcpy(insecret, secret, hashlen);
ret = 1;
err:
OPENSSL_cleanse(secret, sizeof(secret));
return ret;
}
int tls13_alert_code(int code)
{
if (code == SSL_AD_MISSING_EXTENSION)
return code;
return tls1_alert_code(code);
}
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