| /* |
| * TLS 1.3 key schedule |
| * |
| * Copyright The Mbed TLS Contributors |
| * 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. |
| */ |
| |
| #include "common.h" |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| |
| #include <stdint.h> |
| #include <string.h> |
| |
| #include "mbedtls/hkdf.h" |
| #include "mbedtls/debug.h" |
| #include "mbedtls/error.h" |
| #include "mbedtls/platform.h" |
| |
| #include "ssl_misc.h" |
| #include "ssl_tls13_keys.h" |
| #include "ssl_tls13_invasive.h" |
| |
| #include "psa/crypto.h" |
| |
| #define MBEDTLS_SSL_TLS1_3_LABEL( name, string ) \ |
| .name = string, |
| |
| struct mbedtls_ssl_tls13_labels_struct const mbedtls_ssl_tls13_labels = |
| { |
| /* This seems to work in C, despite the string literal being one |
| * character too long due to the 0-termination. */ |
| MBEDTLS_SSL_TLS1_3_LABEL_LIST |
| }; |
| |
| #undef MBEDTLS_SSL_TLS1_3_LABEL |
| |
| /* |
| * This function creates a HkdfLabel structure used in the TLS 1.3 key schedule. |
| * |
| * The HkdfLabel is specified in RFC 8446 as follows: |
| * |
| * struct HkdfLabel { |
| * uint16 length; // Length of expanded key material |
| * opaque label<7..255>; // Always prefixed by "tls13 " |
| * opaque context<0..255>; // Usually a communication transcript hash |
| * }; |
| * |
| * Parameters: |
| * - desired_length: Length of expanded key material |
| * Even though the standard allows expansion to up to |
| * 2**16 Bytes, TLS 1.3 never uses expansion to more than |
| * 255 Bytes, so we require `desired_length` to be at most |
| * 255. This allows us to save a few Bytes of code by |
| * hardcoding the writing of the high bytes. |
| * - (label, label_len): label + label length, without "tls13 " prefix |
| * The label length MUST be less than or equal to |
| * MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN |
| * It is the caller's responsibility to ensure this. |
| * All (label, label length) pairs used in TLS 1.3 |
| * can be obtained via MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN(). |
| * - (ctx, ctx_len): context + context length |
| * The context length MUST be less than or equal to |
| * MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN |
| * It is the caller's responsibility to ensure this. |
| * - dst: Target buffer for HkdfLabel structure, |
| * This MUST be a writable buffer of size |
| * at least SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN Bytes. |
| * - dst_len: Pointer at which to store the actual length of |
| * the HkdfLabel structure on success. |
| */ |
| |
| static const char tls13_label_prefix[6] = "tls13 "; |
| |
| #define SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( label_len, context_len ) \ |
| ( 2 /* expansion length */ \ |
| + 1 /* label length */ \ |
| + label_len \ |
| + 1 /* context length */ \ |
| + context_len ) |
| |
| #define SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN \ |
| SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( \ |
| sizeof(tls13_label_prefix) + \ |
| MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN, \ |
| MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN ) |
| |
| static void ssl_tls13_hkdf_encode_label( |
| size_t desired_length, |
| const unsigned char *label, size_t label_len, |
| const unsigned char *ctx, size_t ctx_len, |
| unsigned char *dst, size_t *dst_len ) |
| { |
| size_t total_label_len = |
| sizeof(tls13_label_prefix) + label_len; |
| size_t total_hkdf_lbl_len = |
| SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( total_label_len, ctx_len ); |
| |
| unsigned char *p = dst; |
| |
| /* Add the size of the expanded key material. |
| * We're hardcoding the high byte to 0 here assuming that we never use |
| * TLS 1.3 HKDF key expansion to more than 255 Bytes. */ |
| #if MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN > 255 |
| #error "The implementation of ssl_tls13_hkdf_encode_label() is not fit for the \ |
| value of MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN" |
| #endif |
| |
| *p++ = 0; |
| *p++ = MBEDTLS_BYTE_0( desired_length ); |
| |
| /* Add label incl. prefix */ |
| *p++ = MBEDTLS_BYTE_0( total_label_len ); |
| memcpy( p, tls13_label_prefix, sizeof(tls13_label_prefix) ); |
| p += sizeof(tls13_label_prefix); |
| memcpy( p, label, label_len ); |
| p += label_len; |
| |
| /* Add context value */ |
| *p++ = MBEDTLS_BYTE_0( ctx_len ); |
| if( ctx_len != 0 ) |
| memcpy( p, ctx, ctx_len ); |
| |
| /* Return total length to the caller. */ |
| *dst_len = total_hkdf_lbl_len; |
| } |
| |
| MBEDTLS_STATIC_TESTABLE |
| psa_status_t mbedtls_psa_hkdf_extract( psa_algorithm_t hash_alg, |
| const unsigned char *salt, size_t salt_len, |
| const unsigned char *ikm, size_t ikm_len, |
| unsigned char *prk, size_t prk_size, |
| size_t *prk_len ) |
| { |
| unsigned char null_salt[PSA_MAC_MAX_SIZE] = { '\0' }; |
| mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT; |
| psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; |
| psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; |
| psa_status_t destroy_status = PSA_ERROR_CORRUPTION_DETECTED; |
| psa_algorithm_t alg = PSA_ALG_HMAC( hash_alg ); |
| |
| if( salt == NULL || salt_len == 0 ) |
| { |
| size_t hash_len; |
| |
| if( salt_len != 0 ) |
| { |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| |
| hash_len = PSA_HASH_LENGTH( alg ); |
| |
| if( hash_len == 0 ) |
| { |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| |
| /* salt_len <= sizeof( salt ) because |
| PSA_HASH_LENGTH( alg ) <= PSA_MAC_MAX_SIZE. */ |
| salt = null_salt; |
| salt_len = hash_len; |
| } |
| |
| psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_SIGN_MESSAGE ); |
| psa_set_key_algorithm( &attributes, alg ); |
| psa_set_key_type( &attributes, PSA_KEY_TYPE_HMAC ); |
| |
| status = psa_import_key( &attributes, salt, salt_len, &key ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| status = psa_mac_compute( key, alg, ikm, ikm_len, prk, prk_size, prk_len ); |
| |
| cleanup: |
| destroy_status = psa_destroy_key( key ); |
| |
| return( ( status == PSA_SUCCESS ) ? destroy_status : status ); |
| } |
| |
| MBEDTLS_STATIC_TESTABLE |
| psa_status_t mbedtls_psa_hkdf_expand( psa_algorithm_t hash_alg, |
| 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; |
| mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT; |
| psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; |
| psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; |
| psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; |
| psa_status_t destroy_status = PSA_ERROR_CORRUPTION_DETECTED; |
| unsigned char t[PSA_MAC_MAX_SIZE]; |
| psa_algorithm_t alg = PSA_ALG_HMAC( hash_alg ); |
| |
| if( okm == NULL ) |
| { |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| |
| hash_len = PSA_HASH_LENGTH( alg ); |
| |
| if( prk_len < hash_len || hash_len == 0 ) |
| { |
| return( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| |
| 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( PSA_ERROR_INVALID_ARGUMENT ); |
| } |
| |
| psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_SIGN_MESSAGE ); |
| psa_set_key_algorithm( &attributes, alg ); |
| psa_set_key_type( &attributes, PSA_KEY_TYPE_HMAC ); |
| |
| status = psa_import_key( &attributes, prk, prk_len, &key ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| memset( t, 0, hash_len ); |
| |
| /* |
| * 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; |
| size_t len; |
| |
| status = psa_mac_sign_setup( &operation, key, alg ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| status = psa_mac_update( &operation, t, t_len ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| status = psa_mac_update( &operation, info, info_len ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| /* The constant concatenated to the end of each T(n) is a single octet. */ |
| status = psa_mac_update( &operation, &c, 1 ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| status = psa_mac_sign_finish( &operation, t, PSA_MAC_MAX_SIZE, &len ); |
| if( status != PSA_SUCCESS ) |
| { |
| goto cleanup; |
| } |
| |
| num_to_copy = i != n ? hash_len : okm_len - where; |
| memcpy( okm + where, t, num_to_copy ); |
| where += hash_len; |
| t_len = hash_len; |
| } |
| |
| cleanup: |
| if( status != PSA_SUCCESS ) |
| psa_mac_abort( &operation ); |
| destroy_status = psa_destroy_key( key ); |
| |
| mbedtls_platform_zeroize( t, sizeof( t ) ); |
| |
| return( ( status == PSA_SUCCESS ) ? destroy_status : status ); |
| } |
| |
| int mbedtls_ssl_tls13_hkdf_expand_label( |
| psa_algorithm_t hash_alg, |
| const unsigned char *secret, size_t secret_len, |
| const unsigned char *label, size_t label_len, |
| const unsigned char *ctx, size_t ctx_len, |
| unsigned char *buf, size_t buf_len ) |
| { |
| unsigned char hkdf_label[ SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN ]; |
| size_t hkdf_label_len; |
| |
| if( label_len > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN ) |
| { |
| /* Should never happen since this is an internal |
| * function, and we know statically which labels |
| * are allowed. */ |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| if( ctx_len > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN ) |
| { |
| /* Should not happen, as above. */ |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| if( buf_len > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN ) |
| { |
| /* Should not happen, as above. */ |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| ssl_tls13_hkdf_encode_label( buf_len, |
| label, label_len, |
| ctx, ctx_len, |
| hkdf_label, |
| &hkdf_label_len ); |
| |
| return( psa_ssl_status_to_mbedtls( |
| mbedtls_psa_hkdf_expand( hash_alg, |
| secret, secret_len, |
| hkdf_label, hkdf_label_len, |
| buf, buf_len ) ) ); |
| } |
| |
| /* |
| * The traffic keying material is generated from the following inputs: |
| * |
| * - One secret value per sender. |
| * - A purpose value indicating the specific value being generated |
| * - The desired lengths of key and IV. |
| * |
| * The expansion itself is based on HKDF: |
| * |
| * [sender]_write_key = HKDF-Expand-Label( Secret, "key", "", key_length ) |
| * [sender]_write_iv = HKDF-Expand-Label( Secret, "iv" , "", iv_length ) |
| * |
| * [sender] denotes the sending side and the Secret value is provided |
| * by the function caller. Note that we generate server and client side |
| * keys in a single function call. |
| */ |
| int mbedtls_ssl_tls13_make_traffic_keys( |
| psa_algorithm_t hash_alg, |
| const unsigned char *client_secret, |
| const unsigned char *server_secret, size_t secret_len, |
| size_t key_len, size_t iv_len, |
| mbedtls_ssl_key_set *keys ) |
| { |
| int ret = 0; |
| |
| ret = mbedtls_ssl_tls13_hkdf_expand_label( hash_alg, |
| client_secret, secret_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ), |
| NULL, 0, |
| keys->client_write_key, key_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| ret = mbedtls_ssl_tls13_hkdf_expand_label( hash_alg, |
| server_secret, secret_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ), |
| NULL, 0, |
| keys->server_write_key, key_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| ret = mbedtls_ssl_tls13_hkdf_expand_label( hash_alg, |
| client_secret, secret_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ), |
| NULL, 0, |
| keys->client_write_iv, iv_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| ret = mbedtls_ssl_tls13_hkdf_expand_label( hash_alg, |
| server_secret, secret_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ), |
| NULL, 0, |
| keys->server_write_iv, iv_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| keys->key_len = key_len; |
| keys->iv_len = iv_len; |
| |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_derive_secret( |
| psa_algorithm_t hash_alg, |
| const unsigned char *secret, size_t secret_len, |
| const unsigned char *label, size_t label_len, |
| const unsigned char *ctx, size_t ctx_len, |
| int ctx_hashed, |
| unsigned char *dstbuf, size_t dstbuf_len ) |
| { |
| int ret; |
| unsigned char hashed_context[ PSA_HASH_MAX_SIZE ]; |
| if( ctx_hashed == MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED ) |
| { |
| psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; |
| |
| status = psa_hash_compute( hash_alg, ctx, ctx_len, hashed_context, |
| PSA_HASH_LENGTH( hash_alg ), &ctx_len ); |
| if( status != PSA_SUCCESS ) |
| { |
| ret = psa_ssl_status_to_mbedtls( status ); |
| return ret; |
| } |
| } |
| else |
| { |
| if( ctx_len > sizeof(hashed_context) ) |
| { |
| /* This should never happen since this function is internal |
| * and the code sets `ctx_hashed` correctly. |
| * Let's double-check nonetheless to not run at the risk |
| * of getting a stack overflow. */ |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| memcpy( hashed_context, ctx, ctx_len ); |
| } |
| |
| return( mbedtls_ssl_tls13_hkdf_expand_label( hash_alg, |
| secret, secret_len, |
| label, label_len, |
| hashed_context, ctx_len, |
| dstbuf, dstbuf_len ) ); |
| |
| } |
| |
| int mbedtls_ssl_tls13_evolve_secret( |
| psa_algorithm_t hash_alg, |
| const unsigned char *secret_old, |
| const unsigned char *input, size_t input_len, |
| unsigned char *secret_new ) |
| { |
| int ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; |
| size_t hlen, ilen; |
| unsigned char tmp_secret[ PSA_MAC_MAX_SIZE ] = { 0 }; |
| unsigned char tmp_input [ MBEDTLS_ECP_MAX_BYTES ] = { 0 }; |
| size_t secret_len; |
| |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| hlen = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* For non-initial runs, call Derive-Secret( ., "derived", "") |
| * on the old secret. */ |
| if( secret_old != NULL ) |
| { |
| ret = mbedtls_ssl_tls13_derive_secret( |
| hash_alg, |
| secret_old, hlen, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( derived ), |
| NULL, 0, /* context */ |
| MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED, |
| tmp_secret, hlen ); |
| if( ret != 0 ) |
| goto cleanup; |
| } |
| |
| if( input != NULL ) |
| { |
| memcpy( tmp_input, input, input_len ); |
| ilen = input_len; |
| } |
| else |
| { |
| ilen = hlen; |
| } |
| |
| /* HKDF-Extract takes a salt and input key material. |
| * The salt is the old secret, and the input key material |
| * is the input secret (PSK / ECDHE). */ |
| ret = psa_ssl_status_to_mbedtls( |
| mbedtls_psa_hkdf_extract( hash_alg, |
| tmp_secret, hlen, |
| tmp_input, ilen, |
| secret_new, hlen, &secret_len ) ); |
| |
| cleanup: |
| |
| mbedtls_platform_zeroize( tmp_secret, sizeof(tmp_secret) ); |
| mbedtls_platform_zeroize( tmp_input, sizeof(tmp_input) ); |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_derive_early_secrets( |
| psa_algorithm_t hash_alg, |
| unsigned char const *early_secret, |
| unsigned char const *transcript, size_t transcript_len, |
| mbedtls_ssl_tls13_early_secrets *derived ) |
| { |
| int ret; |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| /* |
| * 0 |
| * | |
| * v |
| * PSK -> HKDF-Extract = Early Secret |
| * | |
| * +-----> Derive-Secret(., "c e traffic", ClientHello) |
| * | = client_early_traffic_secret |
| * | |
| * +-----> Derive-Secret(., "e exp master", ClientHello) |
| * | = early_exporter_master_secret |
| * v |
| */ |
| |
| /* Create client_early_traffic_secret */ |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| early_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( c_e_traffic ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->client_early_traffic_secret, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| /* Create early exporter */ |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| early_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( e_exp_master ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->early_exporter_master_secret, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_derive_handshake_secrets( |
| psa_algorithm_t hash_alg, |
| unsigned char const *handshake_secret, |
| unsigned char const *transcript, size_t transcript_len, |
| mbedtls_ssl_tls13_handshake_secrets *derived ) |
| { |
| int ret; |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| /* |
| * |
| * Handshake Secret |
| * | |
| * +-----> Derive-Secret( ., "c hs traffic", |
| * | ClientHello...ServerHello ) |
| * | = client_handshake_traffic_secret |
| * | |
| * +-----> Derive-Secret( ., "s hs traffic", |
| * | ClientHello...ServerHello ) |
| * | = server_handshake_traffic_secret |
| * |
| */ |
| |
| /* |
| * Compute client_handshake_traffic_secret with |
| * Derive-Secret( ., "c hs traffic", ClientHello...ServerHello ) |
| */ |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| handshake_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( c_hs_traffic ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->client_handshake_traffic_secret, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| /* |
| * Compute server_handshake_traffic_secret with |
| * Derive-Secret( ., "s hs traffic", ClientHello...ServerHello ) |
| */ |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| handshake_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( s_hs_traffic ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->server_handshake_traffic_secret, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_derive_application_secrets( |
| psa_algorithm_t hash_alg, |
| unsigned char const *application_secret, |
| unsigned char const *transcript, size_t transcript_len, |
| mbedtls_ssl_tls13_application_secrets *derived ) |
| { |
| int ret; |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| /* Generate {client,server}_application_traffic_secret_0 |
| * |
| * Master Secret |
| * | |
| * +-----> Derive-Secret( ., "c ap traffic", |
| * | ClientHello...server Finished ) |
| * | = client_application_traffic_secret_0 |
| * | |
| * +-----> Derive-Secret( ., "s ap traffic", |
| * | ClientHello...Server Finished ) |
| * | = server_application_traffic_secret_0 |
| * | |
| * +-----> Derive-Secret( ., "exp master", |
| * | ClientHello...server Finished) |
| * | = exporter_master_secret |
| * |
| */ |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| application_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( c_ap_traffic ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->client_application_traffic_secret_N, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| application_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( s_ap_traffic ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->server_application_traffic_secret_N, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| application_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( exp_master ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->exporter_master_secret, |
| hash_len ); |
| if( ret != 0 ) |
| return( ret ); |
| |
| return( 0 ); |
| } |
| |
| /* Generate resumption_master_secret for use with the ticket exchange. |
| * |
| * This is not integrated with mbedtls_ssl_tls13_derive_application_secrets() |
| * because it uses the transcript hash up to and including ClientFinished. */ |
| int mbedtls_ssl_tls13_derive_resumption_master_secret( |
| psa_algorithm_t hash_alg, |
| unsigned char const *application_secret, |
| unsigned char const *transcript, size_t transcript_len, |
| mbedtls_ssl_tls13_application_secrets *derived ) |
| { |
| int ret; |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| application_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( res_master ), |
| transcript, transcript_len, |
| MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED, |
| derived->resumption_master_secret, |
| hash_len ); |
| |
| if( ret != 0 ) |
| return( ret ); |
| |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_key_schedule_stage_application( mbedtls_ssl_context *ssl ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| psa_algorithm_t const hash_alg = mbedtls_psa_translate_md( |
| handshake->ciphersuite_info->mac ); |
| |
| /* |
| * Compute MasterSecret |
| */ |
| ret = mbedtls_ssl_tls13_evolve_secret( hash_alg, |
| handshake->tls13_master_secrets.handshake, |
| NULL, 0, |
| handshake->tls13_master_secrets.app ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_evolve_secret", ret ); |
| return( ret ); |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Master secret", |
| handshake->tls13_master_secrets.app, PSA_HASH_LENGTH( hash_alg ) ); |
| |
| return( 0 ); |
| } |
| |
| static int ssl_tls13_calc_finished_core( psa_algorithm_t hash_alg, |
| unsigned char const *base_key, |
| unsigned char const *transcript, |
| unsigned char *dst, |
| size_t *dst_len ) |
| { |
| mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT; |
| psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; |
| psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; |
| size_t hash_len = PSA_HASH_LENGTH( hash_alg ); |
| unsigned char finished_key[PSA_MAC_MAX_SIZE]; |
| int ret; |
| psa_algorithm_t alg; |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| /* TLS 1.3 Finished message |
| * |
| * struct { |
| * opaque verify_data[Hash.length]; |
| * } Finished; |
| * |
| * verify_data = |
| * HMAC( finished_key, |
| * Hash( Handshake Context + |
| * Certificate* + |
| * CertificateVerify* ) |
| * ) |
| * |
| * finished_key = |
| * HKDF-Expand-Label( BaseKey, "finished", "", Hash.length ) |
| */ |
| |
| ret = mbedtls_ssl_tls13_hkdf_expand_label( |
| hash_alg, base_key, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( finished ), |
| NULL, 0, |
| finished_key, hash_len ); |
| if( ret != 0 ) |
| goto exit; |
| |
| alg = PSA_ALG_HMAC( hash_alg ); |
| psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_SIGN_MESSAGE ); |
| psa_set_key_algorithm( &attributes, alg ); |
| psa_set_key_type( &attributes, PSA_KEY_TYPE_HMAC ); |
| |
| status = psa_import_key( &attributes, finished_key, hash_len, &key ); |
| if( status != PSA_SUCCESS ) |
| { |
| ret = psa_ssl_status_to_mbedtls( status ); |
| goto exit; |
| } |
| |
| status = psa_mac_compute( key, alg, transcript, hash_len, |
| dst, hash_len, dst_len ); |
| ret = psa_ssl_status_to_mbedtls( status ); |
| |
| exit: |
| |
| status = psa_destroy_key( key ); |
| if( ret == 0 ) |
| ret = psa_ssl_status_to_mbedtls( status ); |
| |
| mbedtls_platform_zeroize( finished_key, sizeof( finished_key ) ); |
| |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_calculate_verify_data( mbedtls_ssl_context* ssl, |
| unsigned char* dst, |
| size_t dst_len, |
| size_t *actual_len, |
| int from ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| |
| unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE]; |
| size_t transcript_len; |
| |
| unsigned char *base_key = NULL; |
| size_t base_key_len = 0; |
| mbedtls_ssl_tls13_handshake_secrets *tls13_hs_secrets = |
| &ssl->handshake->tls13_hs_secrets; |
| |
| mbedtls_md_type_t const md_type = ssl->handshake->ciphersuite_info->mac; |
| |
| psa_algorithm_t hash_alg = mbedtls_psa_translate_md( |
| ssl->handshake->ciphersuite_info->mac ); |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_tls13_calculate_verify_data" ) ); |
| |
| if( from == MBEDTLS_SSL_IS_CLIENT ) |
| { |
| base_key = tls13_hs_secrets->client_handshake_traffic_secret; |
| base_key_len = sizeof( tls13_hs_secrets->client_handshake_traffic_secret ); |
| } |
| else |
| { |
| base_key = tls13_hs_secrets->server_handshake_traffic_secret; |
| base_key_len = sizeof( tls13_hs_secrets->server_handshake_traffic_secret ); |
| } |
| |
| if( dst_len < hash_len ) |
| { |
| ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; |
| goto exit; |
| } |
| |
| ret = mbedtls_ssl_get_handshake_transcript( ssl, md_type, |
| transcript, sizeof( transcript ), |
| &transcript_len ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_get_handshake_transcript", ret ); |
| goto exit; |
| } |
| MBEDTLS_SSL_DEBUG_BUF( 4, "handshake hash", transcript, transcript_len ); |
| |
| ret = ssl_tls13_calc_finished_core( hash_alg, base_key, transcript, dst, actual_len ); |
| if( ret != 0 ) |
| goto exit; |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "verify_data for finished message", dst, hash_len ); |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_tls13_calculate_verify_data" ) ); |
| |
| exit: |
| /* Erase handshake secrets */ |
| mbedtls_platform_zeroize( base_key, base_key_len ); |
| mbedtls_platform_zeroize( transcript, sizeof( transcript ) ); |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_create_psk_binder( mbedtls_ssl_context *ssl, |
| const psa_algorithm_t hash_alg, |
| unsigned char const *psk, size_t psk_len, |
| int psk_type, |
| unsigned char const *transcript, |
| unsigned char *result ) |
| { |
| int ret = 0; |
| unsigned char binder_key[PSA_MAC_MAX_SIZE]; |
| unsigned char early_secret[PSA_MAC_MAX_SIZE]; |
| size_t const hash_len = PSA_HASH_LENGTH( hash_alg ); |
| size_t actual_len; |
| |
| #if !defined(MBEDTLS_DEBUG_C) |
| ssl = NULL; /* make sure we don't use it except for debug */ |
| ((void) ssl); |
| #endif |
| |
| /* We should never call this function with an unknown hash, |
| * but add an assertion anyway. */ |
| if( ! PSA_ALG_IS_HASH( hash_alg ) ) |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| |
| /* |
| * 0 |
| * | |
| * v |
| * PSK -> HKDF-Extract = Early Secret |
| * | |
| * +-----> Derive-Secret(., "ext binder" | "res binder", "") |
| * | = binder_key |
| * v |
| */ |
| |
| ret = mbedtls_ssl_tls13_evolve_secret( hash_alg, |
| NULL, /* Old secret */ |
| psk, psk_len, /* Input */ |
| early_secret ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_evolve_secret", ret ); |
| goto exit; |
| } |
| |
| if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION ) |
| { |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| early_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( res_binder ), |
| NULL, 0, MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED, |
| binder_key, hash_len ); |
| MBEDTLS_SSL_DEBUG_MSG( 4, ( "Derive Early Secret with 'res binder'" ) ); |
| } |
| else |
| { |
| ret = mbedtls_ssl_tls13_derive_secret( hash_alg, |
| early_secret, hash_len, |
| MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( ext_binder ), |
| NULL, 0, MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED, |
| binder_key, hash_len ); |
| MBEDTLS_SSL_DEBUG_MSG( 4, ( "Derive Early Secret with 'ext binder'" ) ); |
| } |
| |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_derive_secret", ret ); |
| goto exit; |
| } |
| |
| /* |
| * The binding_value is computed in the same way as the Finished message |
| * but with the BaseKey being the binder_key. |
| */ |
| |
| ret = ssl_tls13_calc_finished_core( hash_alg, binder_key, transcript, |
| result, &actual_len ); |
| if( ret != 0 ) |
| goto exit; |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder", result, actual_len ); |
| |
| exit: |
| |
| mbedtls_platform_zeroize( early_secret, sizeof( early_secret ) ); |
| mbedtls_platform_zeroize( binder_key, sizeof( binder_key ) ); |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_populate_transform( mbedtls_ssl_transform *transform, |
| int endpoint, |
| int ciphersuite, |
| mbedtls_ssl_key_set const *traffic_keys, |
| mbedtls_ssl_context *ssl /* DEBUG ONLY */ ) |
| { |
| #if !defined(MBEDTLS_USE_PSA_CRYPTO) |
| int ret; |
| mbedtls_cipher_info_t const *cipher_info; |
| #endif /* MBEDTLS_USE_PSA_CRYPTO */ |
| const mbedtls_ssl_ciphersuite_t *ciphersuite_info; |
| unsigned char const *key_enc; |
| unsigned char const *iv_enc; |
| unsigned char const *key_dec; |
| unsigned char const *iv_dec; |
| |
| #if defined(MBEDTLS_USE_PSA_CRYPTO) |
| psa_key_type_t key_type; |
| psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; |
| psa_algorithm_t alg; |
| size_t key_bits; |
| psa_status_t status = PSA_SUCCESS; |
| #endif |
| |
| #if !defined(MBEDTLS_DEBUG_C) |
| ssl = NULL; /* make sure we don't use it except for those cases */ |
| (void) ssl; |
| #endif |
| |
| ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuite ); |
| if( ciphersuite_info == NULL ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite info for %d not found", |
| ciphersuite ) ); |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| } |
| |
| #if !defined(MBEDTLS_USE_PSA_CRYPTO) |
| cipher_info = mbedtls_cipher_info_from_type( ciphersuite_info->cipher ); |
| if( cipher_info == NULL ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher info for %u not found", |
| ciphersuite_info->cipher ) ); |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| } |
| |
| /* |
| * Setup cipher contexts in target transform |
| */ |
| if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_enc, |
| cipher_info ) ) != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret ); |
| return( ret ); |
| } |
| |
| if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_dec, |
| cipher_info ) ) != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret ); |
| return( ret ); |
| } |
| #endif /* MBEDTLS_USE_PSA_CRYPTO */ |
| |
| #if defined(MBEDTLS_SSL_SRV_C) |
| if( endpoint == MBEDTLS_SSL_IS_SERVER ) |
| { |
| key_enc = traffic_keys->server_write_key; |
| key_dec = traffic_keys->client_write_key; |
| iv_enc = traffic_keys->server_write_iv; |
| iv_dec = traffic_keys->client_write_iv; |
| } |
| else |
| #endif /* MBEDTLS_SSL_SRV_C */ |
| #if defined(MBEDTLS_SSL_CLI_C) |
| if( endpoint == MBEDTLS_SSL_IS_CLIENT ) |
| { |
| key_enc = traffic_keys->client_write_key; |
| key_dec = traffic_keys->server_write_key; |
| iv_enc = traffic_keys->client_write_iv; |
| iv_dec = traffic_keys->server_write_iv; |
| } |
| else |
| #endif /* MBEDTLS_SSL_CLI_C */ |
| { |
| /* should not happen */ |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| memcpy( transform->iv_enc, iv_enc, traffic_keys->iv_len ); |
| memcpy( transform->iv_dec, iv_dec, traffic_keys->iv_len ); |
| |
| #if !defined(MBEDTLS_USE_PSA_CRYPTO) |
| if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_enc, |
| key_enc, cipher_info->key_bitlen, |
| MBEDTLS_ENCRYPT ) ) != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret ); |
| return( ret ); |
| } |
| |
| if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_dec, |
| key_dec, cipher_info->key_bitlen, |
| MBEDTLS_DECRYPT ) ) != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret ); |
| return( ret ); |
| } |
| #endif /* MBEDTLS_USE_PSA_CRYPTO */ |
| |
| /* |
| * Setup other fields in SSL transform |
| */ |
| |
| if( ( ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_SHORT_TAG ) != 0 ) |
| transform->taglen = 8; |
| else |
| transform->taglen = 16; |
| |
| transform->ivlen = traffic_keys->iv_len; |
| transform->maclen = 0; |
| transform->fixed_ivlen = transform->ivlen; |
| transform->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; |
| |
| /* We add the true record content type (1 Byte) to the plaintext and |
| * then pad to the configured granularity. The minimum length of the |
| * type-extended and padded plaintext is therefore the padding |
| * granularity. */ |
| transform->minlen = |
| transform->taglen + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY; |
| |
| #if defined(MBEDTLS_USE_PSA_CRYPTO) |
| /* |
| * Setup psa keys and alg |
| */ |
| if( ( status = mbedtls_ssl_cipher_to_psa( ciphersuite_info->cipher, |
| transform->taglen, |
| &alg, |
| &key_type, |
| &key_bits ) ) != PSA_SUCCESS ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_cipher_to_psa", psa_ssl_status_to_mbedtls( status ) ); |
| return( psa_ssl_status_to_mbedtls( status ) ); |
| } |
| |
| transform->psa_alg = alg; |
| |
| if ( alg != MBEDTLS_SSL_NULL_CIPHER ) |
| { |
| psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT ); |
| psa_set_key_algorithm( &attributes, alg ); |
| psa_set_key_type( &attributes, key_type ); |
| |
| if( ( status = psa_import_key( &attributes, |
| key_enc, |
| PSA_BITS_TO_BYTES( key_bits ), |
| &transform->psa_key_enc ) ) != PSA_SUCCESS ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "psa_import_key", psa_ssl_status_to_mbedtls( status ) ); |
| return( psa_ssl_status_to_mbedtls( status ) ); |
| } |
| |
| psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_DECRYPT ); |
| |
| if( ( status = psa_import_key( &attributes, |
| key_dec, |
| PSA_BITS_TO_BYTES( key_bits ), |
| &transform->psa_key_dec ) ) != PSA_SUCCESS ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "psa_import_key", psa_ssl_status_to_mbedtls( status ) ); |
| return( psa_ssl_status_to_mbedtls( status ) ); |
| } |
| } |
| #endif /* MBEDTLS_USE_PSA_CRYPTO */ |
| |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_key_schedule_stage_early( mbedtls_ssl_context *ssl ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| psa_algorithm_t hash_alg; |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| |
| if( handshake->ciphersuite_info == NULL ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher suite info not found" ) ); |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| hash_alg = mbedtls_psa_translate_md( handshake->ciphersuite_info->mac ); |
| |
| ret = mbedtls_ssl_tls13_evolve_secret( hash_alg, NULL, NULL, 0, |
| handshake->tls13_master_secrets.early ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_evolve_secret", ret ); |
| return( ret ); |
| } |
| |
| return( 0 ); |
| } |
| |
| static int mbedtls_ssl_tls13_get_cipher_key_info( |
| const mbedtls_ssl_ciphersuite_t *ciphersuite_info, |
| size_t *key_len, size_t *iv_len ) |
| { |
| psa_key_type_t key_type; |
| psa_algorithm_t alg; |
| size_t taglen; |
| size_t key_bits; |
| psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; |
| |
| if( ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_SHORT_TAG ) |
| taglen = 8; |
| else |
| taglen = 16; |
| |
| status = mbedtls_ssl_cipher_to_psa( ciphersuite_info->cipher, taglen, |
| &alg, &key_type, &key_bits ); |
| if( status != PSA_SUCCESS ) |
| return psa_ssl_status_to_mbedtls( status ); |
| |
| *key_len = PSA_BITS_TO_BYTES( key_bits ); |
| |
| /* TLS 1.3 only have AEAD ciphers, IV length is unconditionally 12 bytes */ |
| *iv_len = 12; |
| |
| return 0; |
| } |
| |
| /* mbedtls_ssl_tls13_generate_handshake_keys() generates keys necessary for |
| * protecting the handshake messages, as described in Section 7 of TLS 1.3. */ |
| int mbedtls_ssl_tls13_generate_handshake_keys( mbedtls_ssl_context *ssl, |
| mbedtls_ssl_key_set *traffic_keys ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| |
| mbedtls_md_type_t md_type; |
| |
| psa_algorithm_t hash_alg; |
| size_t hash_len; |
| |
| unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE]; |
| size_t transcript_len; |
| |
| size_t key_len, iv_len; |
| |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info; |
| mbedtls_ssl_tls13_handshake_secrets *tls13_hs_secrets = &handshake->tls13_hs_secrets; |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_tls13_generate_handshake_keys" ) ); |
| |
| ret = mbedtls_ssl_tls13_get_cipher_key_info( ciphersuite_info, |
| &key_len, &iv_len ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_get_cipher_key_info", ret ); |
| return ret; |
| } |
| |
| md_type = ciphersuite_info->mac; |
| |
| hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac ); |
| hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| ret = mbedtls_ssl_get_handshake_transcript( ssl, md_type, |
| transcript, |
| sizeof( transcript ), |
| &transcript_len ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_get_handshake_transcript", |
| ret ); |
| return( ret ); |
| } |
| |
| ret = mbedtls_ssl_tls13_derive_handshake_secrets( hash_alg, |
| handshake->tls13_master_secrets.handshake, |
| transcript, transcript_len, tls13_hs_secrets ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_derive_handshake_secrets", |
| ret ); |
| return( ret ); |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Client handshake traffic secret", |
| tls13_hs_secrets->client_handshake_traffic_secret, |
| hash_len ); |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Server handshake traffic secret", |
| tls13_hs_secrets->server_handshake_traffic_secret, |
| hash_len ); |
| |
| /* |
| * Export client handshake traffic secret |
| */ |
| if( ssl->f_export_keys != NULL ) |
| { |
| ssl->f_export_keys( ssl->p_export_keys, |
| MBEDTLS_SSL_KEY_EXPORT_TLS1_3_CLIENT_HANDSHAKE_TRAFFIC_SECRET, |
| tls13_hs_secrets->client_handshake_traffic_secret, |
| hash_len, |
| handshake->randbytes, |
| handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN, |
| MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ ); |
| |
| ssl->f_export_keys( ssl->p_export_keys, |
| MBEDTLS_SSL_KEY_EXPORT_TLS1_3_SERVER_HANDSHAKE_TRAFFIC_SECRET, |
| tls13_hs_secrets->server_handshake_traffic_secret, |
| hash_len, |
| handshake->randbytes, |
| handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN, |
| MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ ); |
| } |
| |
| ret = mbedtls_ssl_tls13_make_traffic_keys( hash_alg, |
| tls13_hs_secrets->client_handshake_traffic_secret, |
| tls13_hs_secrets->server_handshake_traffic_secret, |
| hash_len, key_len, iv_len, traffic_keys ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_make_traffic_keys", ret ); |
| goto exit; |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "client_handshake write_key", |
| traffic_keys->client_write_key, |
| traffic_keys->key_len); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "server_handshake write_key", |
| traffic_keys->server_write_key, |
| traffic_keys->key_len); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "client_handshake write_iv", |
| traffic_keys->client_write_iv, |
| traffic_keys->iv_len); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "server_handshake write_iv", |
| traffic_keys->server_write_iv, |
| traffic_keys->iv_len); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_tls13_generate_handshake_keys" ) ); |
| |
| exit: |
| |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_key_schedule_stage_handshake( mbedtls_ssl_context *ssl ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| #if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED) && defined(MBEDTLS_ECDH_C) |
| psa_status_t status = PSA_ERROR_GENERIC_ERROR; |
| #endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED && MBEDTLS_ECDH_C */ |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| psa_algorithm_t const hash_alg = mbedtls_psa_translate_md( |
| handshake->ciphersuite_info->mac ); |
| |
| #if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED) |
| /* |
| * Compute ECDHE secret used to compute the handshake secret from which |
| * client_handshake_traffic_secret and server_handshake_traffic_secret |
| * are derived in the handshake secret derivation stage. |
| */ |
| if( mbedtls_ssl_tls13_ephemeral_enabled( ssl ) ) |
| { |
| if( mbedtls_ssl_tls13_named_group_is_ecdhe( handshake->offered_group_id ) ) |
| { |
| #if defined(MBEDTLS_ECDH_C) |
| /* Compute ECDH shared secret. */ |
| status = psa_raw_key_agreement( |
| PSA_ALG_ECDH, handshake->ecdh_psa_privkey, |
| handshake->ecdh_psa_peerkey, handshake->ecdh_psa_peerkey_len, |
| handshake->premaster, sizeof( handshake->premaster ), |
| &handshake->pmslen ); |
| if( status != PSA_SUCCESS ) |
| { |
| ret = psa_ssl_status_to_mbedtls( status ); |
| MBEDTLS_SSL_DEBUG_RET( 1, "psa_raw_key_agreement", ret ); |
| return( ret ); |
| } |
| |
| status = psa_destroy_key( handshake->ecdh_psa_privkey ); |
| if( status != PSA_SUCCESS ) |
| { |
| ret = psa_ssl_status_to_mbedtls( status ); |
| MBEDTLS_SSL_DEBUG_RET( 1, "psa_destroy_key", ret ); |
| return( ret ); |
| } |
| |
| handshake->ecdh_psa_privkey = MBEDTLS_SVC_KEY_ID_INIT; |
| #endif /* MBEDTLS_ECDH_C */ |
| } |
| else if( mbedtls_ssl_tls13_named_group_is_dhe( handshake->offered_group_id ) ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "DHE not supported." ) ); |
| return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); |
| } |
| } |
| #else |
| return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); |
| #endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */ |
| |
| /* |
| * Compute the Handshake Secret |
| */ |
| ret = mbedtls_ssl_tls13_evolve_secret( hash_alg, |
| handshake->tls13_master_secrets.early, |
| handshake->premaster, handshake->pmslen, |
| handshake->tls13_master_secrets.handshake ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_evolve_secret", ret ); |
| return( ret ); |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Handshake secret", |
| handshake->tls13_master_secrets.handshake, |
| PSA_HASH_LENGTH( hash_alg ) ); |
| |
| #if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED) |
| mbedtls_platform_zeroize( handshake->premaster, sizeof( handshake->premaster ) ); |
| #endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */ |
| return( 0 ); |
| } |
| |
| /* Generate application traffic keys since any records following a 1-RTT Finished message |
| * MUST be encrypted under the application traffic key. |
| */ |
| int mbedtls_ssl_tls13_generate_application_keys( |
| mbedtls_ssl_context *ssl, |
| mbedtls_ssl_key_set *traffic_keys ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| |
| /* Address at which to store the application secrets */ |
| mbedtls_ssl_tls13_application_secrets * const app_secrets = |
| &ssl->session_negotiate->app_secrets; |
| |
| /* Holding the transcript up to and including the ServerFinished */ |
| unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE]; |
| size_t transcript_len; |
| |
| /* Variables relating to the hash for the chosen ciphersuite. */ |
| mbedtls_md_type_t md_type; |
| |
| psa_algorithm_t hash_alg; |
| size_t hash_len; |
| |
| /* Variables relating to the cipher for the chosen ciphersuite. */ |
| size_t key_len, iv_len; |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> derive application traffic keys" ) ); |
| |
| /* Extract basic information about hash and ciphersuite */ |
| |
| ret = mbedtls_ssl_tls13_get_cipher_key_info( handshake->ciphersuite_info, |
| &key_len, &iv_len ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_get_cipher_key_info", ret ); |
| goto cleanup; |
| } |
| |
| md_type = handshake->ciphersuite_info->mac; |
| |
| hash_alg = mbedtls_psa_translate_md( handshake->ciphersuite_info->mac ); |
| hash_len = PSA_HASH_LENGTH( hash_alg ); |
| |
| /* Compute current handshake transcript. It's the caller's responsibility |
| * to call this at the right time, that is, after the ServerFinished. */ |
| |
| ret = mbedtls_ssl_get_handshake_transcript( ssl, md_type, |
| transcript, sizeof( transcript ), |
| &transcript_len ); |
| if( ret != 0 ) |
| goto cleanup; |
| |
| /* Compute application secrets from master secret and transcript hash. */ |
| |
| ret = mbedtls_ssl_tls13_derive_application_secrets( hash_alg, |
| handshake->tls13_master_secrets.app, |
| transcript, transcript_len, |
| app_secrets ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_tls13_derive_application_secrets", ret ); |
| goto cleanup; |
| } |
| |
| /* Derive first epoch of IV + Key for application traffic. */ |
| |
| ret = mbedtls_ssl_tls13_make_traffic_keys( hash_alg, |
| app_secrets->client_application_traffic_secret_N, |
| app_secrets->server_application_traffic_secret_N, |
| hash_len, key_len, iv_len, traffic_keys ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_make_traffic_keys", ret ); |
| goto cleanup; |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Client application traffic secret", |
| app_secrets->client_application_traffic_secret_N, |
| hash_len ); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "Server application traffic secret", |
| app_secrets->server_application_traffic_secret_N, |
| hash_len ); |
| |
| /* |
| * Export client/server application traffic secret 0 |
| */ |
| if( ssl->f_export_keys != NULL ) |
| { |
| ssl->f_export_keys( ssl->p_export_keys, |
| MBEDTLS_SSL_KEY_EXPORT_TLS1_3_CLIENT_APPLICATION_TRAFFIC_SECRET, |
| app_secrets->client_application_traffic_secret_N, hash_len, |
| handshake->randbytes, |
| handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN, |
| MBEDTLS_SSL_TLS_PRF_NONE /* TODO: this should be replaced by |
| a new constant for TLS 1.3! */ ); |
| |
| ssl->f_export_keys( ssl->p_export_keys, |
| MBEDTLS_SSL_KEY_EXPORT_TLS1_3_SERVER_APPLICATION_TRAFFIC_SECRET, |
| app_secrets->server_application_traffic_secret_N, hash_len, |
| handshake->randbytes, |
| handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN, |
| MBEDTLS_SSL_TLS_PRF_NONE /* TODO: this should be replaced by |
| a new constant for TLS 1.3! */ ); |
| } |
| |
| MBEDTLS_SSL_DEBUG_BUF( 4, "client application_write_key:", |
| traffic_keys->client_write_key, key_len ); |
| MBEDTLS_SSL_DEBUG_BUF( 4, "server application write key", |
| traffic_keys->server_write_key, key_len ); |
| MBEDTLS_SSL_DEBUG_BUF( 4, "client application write IV", |
| traffic_keys->client_write_iv, iv_len ); |
| MBEDTLS_SSL_DEBUG_BUF( 4, "server application write IV", |
| traffic_keys->server_write_iv, iv_len ); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= derive application traffic keys" ) ); |
| |
| cleanup: |
| /* randbytes is not used again */ |
| mbedtls_platform_zeroize( ssl->handshake->randbytes, |
| sizeof( ssl->handshake->randbytes ) ); |
| |
| mbedtls_platform_zeroize( transcript, sizeof( transcript ) ); |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_compute_handshake_transform( mbedtls_ssl_context *ssl ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| mbedtls_ssl_key_set traffic_keys; |
| mbedtls_ssl_transform *transform_handshake = NULL; |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| |
| /* Compute handshake secret */ |
| ret = mbedtls_ssl_tls13_key_schedule_stage_handshake( ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_derive_master_secret", ret ); |
| goto cleanup; |
| } |
| |
| /* Next evolution in key schedule: Establish handshake secret and |
| * key material. */ |
| ret = mbedtls_ssl_tls13_generate_handshake_keys( ssl, &traffic_keys ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_handshake_keys", |
| ret ); |
| goto cleanup; |
| } |
| |
| transform_handshake = mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) ); |
| if( transform_handshake == NULL ) |
| { |
| ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; |
| goto cleanup; |
| } |
| |
| ret = mbedtls_ssl_tls13_populate_transform( |
| transform_handshake, |
| ssl->conf->endpoint, |
| ssl->session_negotiate->ciphersuite, |
| &traffic_keys, |
| ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_populate_transform", ret ); |
| goto cleanup; |
| } |
| handshake->transform_handshake = transform_handshake; |
| |
| cleanup: |
| mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) ); |
| if( ret != 0 ) |
| mbedtls_free( transform_handshake ); |
| |
| return( ret ); |
| } |
| |
| int mbedtls_ssl_tls13_generate_resumption_master_secret( |
| mbedtls_ssl_context *ssl ) |
| { |
| /* Erase master secrets */ |
| mbedtls_platform_zeroize( &ssl->handshake->tls13_master_secrets, |
| sizeof( ssl->handshake->tls13_master_secrets ) ); |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_tls13_compute_application_transform( mbedtls_ssl_context *ssl ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| mbedtls_ssl_key_set traffic_keys; |
| mbedtls_ssl_transform *transform_application = NULL; |
| |
| ret = mbedtls_ssl_tls13_key_schedule_stage_application( ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_tls13_key_schedule_stage_application", ret ); |
| goto cleanup; |
| } |
| |
| ret = mbedtls_ssl_tls13_generate_application_keys( ssl, &traffic_keys ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_tls13_generate_application_keys", ret ); |
| goto cleanup; |
| } |
| |
| transform_application = |
| mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) ); |
| if( transform_application == NULL ) |
| { |
| ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; |
| goto cleanup; |
| } |
| |
| ret = mbedtls_ssl_tls13_populate_transform( |
| transform_application, |
| ssl->conf->endpoint, |
| ssl->session_negotiate->ciphersuite, |
| &traffic_keys, |
| ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_populate_transform", ret ); |
| goto cleanup; |
| } |
| |
| ssl->transform_application = transform_application; |
| |
| cleanup: |
| |
| mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) ); |
| if( ret != 0 ) |
| { |
| mbedtls_free( transform_application ); |
| } |
| return( ret ); |
| } |
| |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ |
