diff options
Diffstat (limited to 'thirdparty/mbedtls/library/hkdf.c')
| -rw-r--r-- | thirdparty/mbedtls/library/hkdf.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/thirdparty/mbedtls/library/hkdf.c b/thirdparty/mbedtls/library/hkdf.c new file mode 100644 index 0000000000..82d8a429f4 --- /dev/null +++ b/thirdparty/mbedtls/library/hkdf.c @@ -0,0 +1,192 @@ +/* + * HKDF implementation -- RFC 5869 + * + * Copyright (C) 2016-2018, ARM Limited, All Rights Reserved + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * This file is part of mbed TLS (https://tls.mbed.org) + */ +#if !defined(MBEDTLS_CONFIG_FILE) +#include "mbedtls/config.h" +#else +#include MBEDTLS_CONFIG_FILE +#endif + +#if defined(MBEDTLS_HKDF_C) + +#include <string.h> +#include "mbedtls/hkdf.h" +#include "mbedtls/platform_util.h" + +int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt, + size_t salt_len, const unsigned char *ikm, size_t ikm_len, + const unsigned char *info, size_t info_len, + unsigned char *okm, size_t okm_len ) +{ + int ret; + unsigned char prk[MBEDTLS_MD_MAX_SIZE]; + + ret = mbedtls_hkdf_extract( md, salt, salt_len, ikm, ikm_len, prk ); + + if( ret == 0 ) + { + ret = mbedtls_hkdf_expand( md, prk, mbedtls_md_get_size( md ), + info, info_len, okm, okm_len ); + } + + mbedtls_platform_zeroize( prk, sizeof( prk ) ); + + return( ret ); +} + +int mbedtls_hkdf_extract( const mbedtls_md_info_t *md, + const unsigned char *salt, size_t salt_len, + const unsigned char *ikm, size_t ikm_len, + unsigned char *prk ) +{ + unsigned char null_salt[MBEDTLS_MD_MAX_SIZE] = { '\0' }; + + if( salt == NULL ) + { + size_t hash_len; + + if( salt_len != 0 ) + { + return MBEDTLS_ERR_HKDF_BAD_INPUT_DATA; + } + + hash_len = mbedtls_md_get_size( md ); + + if( hash_len == 0 ) + { + return MBEDTLS_ERR_HKDF_BAD_INPUT_DATA; + } + + salt = null_salt; + salt_len = hash_len; + } + + return( mbedtls_md_hmac( md, salt, salt_len, ikm, ikm_len, prk ) ); +} + +int mbedtls_hkdf_expand( const mbedtls_md_info_t *md, const unsigned char *prk, + size_t prk_len, const unsigned char *info, + size_t info_len, unsigned char *okm, size_t okm_len ) +{ + size_t hash_len; + size_t where = 0; + size_t n; + size_t t_len = 0; + size_t i; + int ret = 0; + mbedtls_md_context_t ctx; + unsigned char t[MBEDTLS_MD_MAX_SIZE]; + + if( okm == NULL ) + { + return( MBEDTLS_ERR_HKDF_BAD_INPUT_DATA ); + } + + hash_len = mbedtls_md_get_size( md ); + + if( prk_len < hash_len || hash_len == 0 ) + { + return( MBEDTLS_ERR_HKDF_BAD_INPUT_DATA ); + } + + if( info == NULL ) + { + info = (const unsigned char *) ""; + info_len = 0; + } + + n = okm_len / hash_len; + + if( (okm_len % hash_len) != 0 ) + { + n++; + } + + /* + * Per RFC 5869 Section 2.3, okm_len must not exceed + * 255 times the hash length + */ + if( n > 255 ) + { + return( MBEDTLS_ERR_HKDF_BAD_INPUT_DATA ); + } + + mbedtls_md_init( &ctx ); + + if( (ret = mbedtls_md_setup( &ctx, md, 1) ) != 0 ) + { + goto exit; + } + + /* + * Compute T = T(1) | T(2) | T(3) | ... | T(N) + * Where T(N) is defined in RFC 5869 Section 2.3 + */ + for( i = 1; i <= n; i++ ) + { + size_t num_to_copy; + unsigned char c = i & 0xff; + + ret = mbedtls_md_hmac_starts( &ctx, prk, prk_len ); + if( ret != 0 ) + { + goto exit; + } + + ret = mbedtls_md_hmac_update( &ctx, t, t_len ); + if( ret != 0 ) + { + goto exit; + } + + ret = mbedtls_md_hmac_update( &ctx, info, info_len ); + if( ret != 0 ) + { + goto exit; + } + + /* The constant concatenated to the end of each T(n) is a single octet. + * */ + ret = mbedtls_md_hmac_update( &ctx, &c, 1 ); + if( ret != 0 ) + { + goto exit; + } + + ret = mbedtls_md_hmac_finish( &ctx, t ); + if( ret != 0 ) + { + goto exit; + } + + num_to_copy = i != n ? hash_len : okm_len - where; + memcpy( okm + where, t, num_to_copy ); + where += hash_len; + t_len = hash_len; + } + +exit: + mbedtls_md_free( &ctx ); + mbedtls_platform_zeroize( t, sizeof( t ) ); + + return( ret ); +} + +#endif /* MBEDTLS_HKDF_C */ |