130 lines
3.9 KiB
C
130 lines
3.9 KiB
C
// Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
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// SPDX-License-Identifier: Apache-2.0
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#include <assert.h>
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#include <openssl/digest.h>
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#include <openssl/hkdf.h>
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#include <openssl/hmac.h>
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#include <openssl/mem.h>
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#include "../../internal.h"
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// tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246,
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// section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and
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// |secret| as the secret. |label|, |seed1|, and |seed2| are concatenated to
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// form the seed parameter. It returns true on success and false on failure.
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static int tls1_P_hash(uint8_t *out, size_t out_len,
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const EVP_MD *md,
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const uint8_t *secret, size_t secret_len,
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const char *label, size_t label_len,
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const uint8_t *seed1, size_t seed1_len,
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const uint8_t *seed2, size_t seed2_len) {
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HMAC_CTX ctx, ctx_tmp, ctx_init;
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uint8_t A1[EVP_MAX_MD_SIZE];
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unsigned A1_len;
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int ret = 0;
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const size_t chunk = EVP_MD_size(md);
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HMAC_CTX_init(&ctx);
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HMAC_CTX_init(&ctx_tmp);
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HMAC_CTX_init(&ctx_init);
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if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) ||
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!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
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!HMAC_Update(&ctx, (const uint8_t *) label, label_len) ||
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!HMAC_Update(&ctx, seed1, seed1_len) ||
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!HMAC_Update(&ctx, seed2, seed2_len) ||
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!HMAC_Final(&ctx, A1, &A1_len)) {
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goto err;
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}
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for (;;) {
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unsigned len_u;
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uint8_t hmac[EVP_MAX_MD_SIZE];
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if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) ||
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!HMAC_Update(&ctx, A1, A1_len) ||
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// Save a copy of |ctx| to compute the next A1 value below.
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(out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) ||
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!HMAC_Update(&ctx, (const uint8_t *) label, label_len) ||
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!HMAC_Update(&ctx, seed1, seed1_len) ||
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!HMAC_Update(&ctx, seed2, seed2_len) ||
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!HMAC_Final(&ctx, hmac, &len_u)) {
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goto err;
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}
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size_t len = len_u;
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assert(len == chunk);
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// XOR the result into |out|.
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if (len > out_len) {
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len = out_len;
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}
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for (size_t i = 0; i < len; i++) {
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out[i] ^= hmac[i];
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}
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out += len;
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out_len -= len;
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if (out_len == 0) {
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break;
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}
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// Calculate the next A1 value.
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if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) {
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goto err;
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}
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}
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ret = 1;
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err:
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OPENSSL_cleanse(A1, sizeof(A1));
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HMAC_CTX_cleanup(&ctx);
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HMAC_CTX_cleanup(&ctx_tmp);
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HMAC_CTX_cleanup(&ctx_init);
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return ret;
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}
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int CRYPTO_tls1_prf(const EVP_MD *digest,
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uint8_t *out, size_t out_len,
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const uint8_t *secret, size_t secret_len,
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const char *label, size_t label_len,
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const uint8_t *seed1, size_t seed1_len,
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const uint8_t *seed2, size_t seed2_len) {
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// We have to avoid the underlying HMAC services updating the indicator state,
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// so we lock the state here.
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FIPS_service_indicator_lock_state();
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SET_DIT_AUTO_RESET;
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int ret = 0;
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const EVP_MD *original_digest = digest;
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if (out_len == 0) {
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ret = 1;
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goto end;
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}
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OPENSSL_memset(out, 0, out_len);
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if (digest == EVP_md5_sha1()) {
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// If using the MD5/SHA1 PRF, |secret| is partitioned between MD5 and SHA-1.
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size_t secret_half = secret_len - (secret_len / 2);
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if (!tls1_P_hash(out, out_len, EVP_md5(), secret, secret_half, label,
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label_len, seed1, seed1_len, seed2, seed2_len)) {
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goto end;
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}
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// Note that, if |secret_len| is odd, the two halves share a byte.
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secret += secret_len - secret_half;
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secret_len = secret_half;
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digest = EVP_sha1();
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}
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ret = tls1_P_hash(out, out_len, digest, secret, secret_len, label, label_len,
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seed1, seed1_len, seed2, seed2_len);
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end:
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FIPS_service_indicator_unlock_state();
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if(ret) {
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TLSKDF_verify_service_indicator(original_digest, label, label_len);
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}
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return ret;
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}
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