[openssl] master update
shane.lontis at oracle.com
shane.lontis at oracle.com
Fri May 24 00:58:30 UTC 2019
The branch master has been updated
via 0f52d9ed7ed9f9a447131b79f252b8254e69781f (commit)
from e70185883ed08440c2a7d4348fef9f5de3de9295 (commit)
- Log -----------------------------------------------------------------
commit 0f52d9ed7ed9f9a447131b79f252b8254e69781f
Author: David Makepeace <david.p.makepeace at oracle.com>
Date: Thu May 23 14:36:24 2019 +1000
Cleaned up tls1_prf and added comments.
Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Shane Lontis <shane.lontis at oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8987)
-----------------------------------------------------------------------
Summary of changes:
crypto/kdf/tls1_prf.c | 152 ++++++++++++++++++++++++++++++++++++++------------
1 file changed, 117 insertions(+), 35 deletions(-)
diff --git a/crypto/kdf/tls1_prf.c b/crypto/kdf/tls1_prf.c
index 913af29..c39cf20 100644
--- a/crypto/kdf/tls1_prf.c
+++ b/crypto/kdf/tls1_prf.c
@@ -7,6 +7,44 @@
* https://www.openssl.org/source/license.html
*/
+/*
+ * Refer to "The TLS Protocol Version 1.0" Section 5
+ * (https://tools.ietf.org/html/rfc2246#section-5) and
+ * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
+ * (https://tools.ietf.org/html/rfc5246#section-5).
+ *
+ * For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
+ *
+ * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
+ * P_SHA-1(S2, label + seed)
+ *
+ * where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
+ * two halves of the secret (with the possibility of one shared byte, in the
+ * case where the length of the original secret is odd). S1 is taken from the
+ * first half of the secret, S2 from the second half.
+ *
+ * For TLS v1.2 the TLS PRF algorithm is given by:
+ *
+ * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
+ *
+ * where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
+ * those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
+ * unless defined otherwise by the cipher suite.
+ *
+ * P_<hash> is an expansion function that uses a single hash function to expand
+ * a secret and seed into an arbitrary quantity of output:
+ *
+ * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
+ * HMAC_<hash>(secret, A(2) + seed) +
+ * HMAC_<hash>(secret, A(3) + seed) + ...
+ *
+ * where + indicates concatenation. P_<hash> can be iterated as many times as
+ * is necessary to produce the required quantity of data.
+ *
+ * A(i) is defined as:
+ * A(0) = seed
+ * A(i) = HMAC_<hash>(secret, A(i-1))
+ */
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
@@ -82,7 +120,7 @@ static int kdf_tls1_prf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
if (impl->sec == NULL)
return 0;
- impl->seclen = len;
+ impl->seclen = len;
return 1;
case EVP_KDF_CTRL_RESET_TLS_SEED:
@@ -168,25 +206,41 @@ const EVP_KDF tls1_prf_kdf_meth = {
kdf_tls1_prf_derive
};
+/*
+ * Refer to "The TLS Protocol Version 1.0" Section 5
+ * (https://tools.ietf.org/html/rfc2246#section-5) and
+ * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
+ * (https://tools.ietf.org/html/rfc5246#section-5).
+ *
+ * P_<hash> is an expansion function that uses a single hash function to expand
+ * a secret and seed into an arbitrary quantity of output:
+ *
+ * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
+ * HMAC_<hash>(secret, A(2) + seed) +
+ * HMAC_<hash>(secret, A(3) + seed) + ...
+ *
+ * where + indicates concatenation. P_<hash> can be iterated as many times as
+ * is necessary to produce the required quantity of data.
+ *
+ * A(i) is defined as:
+ * A(0) = seed
+ * A(i) = HMAC_<hash>(secret, A(i-1))
+ */
static int tls1_prf_P_hash(const EVP_MD *md,
const unsigned char *sec, size_t sec_len,
const unsigned char *seed, size_t seed_len,
unsigned char *out, size_t olen)
{
- int chunk;
- EVP_MAC_CTX *ctx = NULL, *ctx_tmp = NULL, *ctx_init = NULL;
- unsigned char A1[EVP_MAX_MD_SIZE];
- size_t A1_len;
+ size_t chunk;
+ EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL, *ctx_init = NULL;
+ unsigned char Ai[EVP_MAX_MD_SIZE];
+ size_t Ai_len;
int ret = 0;
- chunk = EVP_MD_size(md);
- if (!ossl_assert(chunk > 0))
- goto err;
-
ctx = EVP_MAC_CTX_new_id(EVP_MAC_HMAC);
- ctx_tmp = EVP_MAC_CTX_new_id(EVP_MAC_HMAC);
+ ctx_Ai = EVP_MAC_CTX_new_id(EVP_MAC_HMAC);
ctx_init = EVP_MAC_CTX_new_id(EVP_MAC_HMAC);
- if (ctx == NULL || ctx_tmp == NULL || ctx_init == NULL)
+ if (ctx == NULL || ctx_Ai == NULL || ctx_init == NULL)
goto err;
if (EVP_MAC_ctrl(ctx_init, EVP_MAC_CTRL_SET_FLAGS, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW) != 1)
goto err;
@@ -196,59 +250,85 @@ static int tls1_prf_P_hash(const EVP_MD *md,
goto err;
if (!EVP_MAC_init(ctx_init))
goto err;
- if (!EVP_MAC_CTX_copy(ctx, ctx_init))
+ chunk = EVP_MAC_size(ctx_init);
+ if (chunk == 0)
goto err;
- if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
+ /* A(0) = seed */
+ if (!EVP_MAC_CTX_copy(ctx_Ai, ctx_init))
goto err;
- if (!EVP_MAC_final(ctx, A1, &A1_len))
+ if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
goto err;
for (;;) {
- /* Reinit mac contexts */
+ /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
+ if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len))
+ goto err;
+
+ /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
if (!EVP_MAC_CTX_copy(ctx, ctx_init))
goto err;
- if (!EVP_MAC_update(ctx, A1, A1_len))
+ if (!EVP_MAC_update(ctx, Ai, Ai_len))
goto err;
- if (olen > (size_t)chunk && !EVP_MAC_CTX_copy(ctx_tmp, ctx))
+ /* save state for calculating next A(i) value */
+ if (olen > chunk && !EVP_MAC_CTX_copy(ctx_Ai, ctx))
goto err;
if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
goto err;
-
- if (olen > (size_t)chunk) {
- size_t mac_len;
- if (!EVP_MAC_final(ctx, out, &mac_len))
- goto err;
- out += mac_len;
- olen -= mac_len;
- /* calc the next A1 value */
- if (!EVP_MAC_final(ctx_tmp, A1, &A1_len))
+ if (olen <= chunk) {
+ /* last chunk - use Ai as temp bounce buffer */
+ if (!EVP_MAC_final(ctx, Ai, &Ai_len))
goto err;
- } else { /* last one */
-
- if (!EVP_MAC_final(ctx, A1, &A1_len))
- goto err;
- memcpy(out, A1, olen);
+ memcpy(out, Ai, olen);
break;
}
+ if (!EVP_MAC_final(ctx, out, NULL))
+ goto err;
+ out += chunk;
+ olen -= chunk;
}
ret = 1;
err:
EVP_MAC_CTX_free(ctx);
- EVP_MAC_CTX_free(ctx_tmp);
+ EVP_MAC_CTX_free(ctx_Ai);
EVP_MAC_CTX_free(ctx_init);
- OPENSSL_cleanse(A1, sizeof(A1));
+ OPENSSL_cleanse(Ai, sizeof(Ai));
return ret;
}
+/*
+ * Refer to "The TLS Protocol Version 1.0" Section 5
+ * (https://tools.ietf.org/html/rfc2246#section-5) and
+ * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
+ * (https://tools.ietf.org/html/rfc5246#section-5).
+ *
+ * For TLS v1.0 and TLS v1.1:
+ *
+ * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
+ * P_SHA-1(S2, label + seed)
+ *
+ * S1 is taken from the first half of the secret, S2 from the second half.
+ *
+ * L_S = length in bytes of secret;
+ * L_S1 = L_S2 = ceil(L_S / 2);
+ *
+ * For TLS v1.2:
+ *
+ * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
+ */
static int tls1_prf_alg(const EVP_MD *md,
const unsigned char *sec, size_t slen,
const unsigned char *seed, size_t seed_len,
unsigned char *out, size_t olen)
{
if (EVP_MD_type(md) == NID_md5_sha1) {
+ /* TLS v1.0 and TLS v1.1 */
size_t i;
unsigned char *tmp;
- if (!tls1_prf_P_hash(EVP_md5(), sec, slen/2 + (slen & 1),
+ /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
+ size_t L_S1 = (slen + 1) / 2;
+ size_t L_S2 = L_S1;
+
+ if (!tls1_prf_P_hash(EVP_md5(), sec, L_S1,
seed, seed_len, out, olen))
return 0;
@@ -256,7 +336,7 @@ static int tls1_prf_alg(const EVP_MD *md,
KDFerr(KDF_F_TLS1_PRF_ALG, ERR_R_MALLOC_FAILURE);
return 0;
}
- if (!tls1_prf_P_hash(EVP_sha1(), sec + slen/2, slen/2 + (slen & 1),
+ if (!tls1_prf_P_hash(EVP_sha1(), sec + slen - L_S2, L_S2,
seed, seed_len, tmp, olen)) {
OPENSSL_clear_free(tmp, olen);
return 0;
@@ -266,6 +346,8 @@ static int tls1_prf_alg(const EVP_MD *md,
OPENSSL_clear_free(tmp, olen);
return 1;
}
+
+ /* TLS v1.2 */
if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))
return 0;
More information about the openssl-commits
mailing list