1034 lines
36 KiB
C
1034 lines
36 KiB
C
/*
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* TLS 1.3 key schedule
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 ( the "License" ); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
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#include <stdint.h>
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#include <string.h>
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#include "mbedtls/hkdf.h"
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#include "mbedtls/debug.h"
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#include "mbedtls/error.h"
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#include "ssl_misc.h"
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#include "ssl_tls13_keys.h"
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#define MBEDTLS_SSL_TLS1_3_LABEL( name, string ) \
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.name = string,
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struct mbedtls_ssl_tls1_3_labels_struct const mbedtls_ssl_tls1_3_labels =
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{
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/* This seems to work in C, despite the string literal being one
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* character too long due to the 0-termination. */
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MBEDTLS_SSL_TLS1_3_LABEL_LIST
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};
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#undef MBEDTLS_SSL_TLS1_3_LABEL
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/*
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* This function creates a HkdfLabel structure used in the TLS 1.3 key schedule.
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*
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* The HkdfLabel is specified in RFC 8446 as follows:
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*
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* struct HkdfLabel {
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* uint16 length; // Length of expanded key material
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* opaque label<7..255>; // Always prefixed by "tls13 "
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* opaque context<0..255>; // Usually a communication transcript hash
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* };
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*
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* Parameters:
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* - desired_length: Length of expanded key material
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* Even though the standard allows expansion to up to
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* 2**16 Bytes, TLS 1.3 never uses expansion to more than
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* 255 Bytes, so we require `desired_length` to be at most
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* 255. This allows us to save a few Bytes of code by
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* hardcoding the writing of the high bytes.
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* - (label, llen): label + label length, without "tls13 " prefix
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* The label length MUST be less than or equal to
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* MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN
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* It is the caller's responsibility to ensure this.
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* All (label, label length) pairs used in TLS 1.3
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* can be obtained via MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN().
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* - (ctx, clen): context + context length
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* The context length MUST be less than or equal to
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* MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN
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* It is the caller's responsibility to ensure this.
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* - dst: Target buffer for HkdfLabel structure,
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* This MUST be a writable buffer of size
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* at least SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN Bytes.
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* - dlen: Pointer at which to store the actual length of
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* the HkdfLabel structure on success.
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*/
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static const char tls1_3_label_prefix[6] = "tls13 ";
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#define SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( label_len, context_len ) \
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( 2 /* expansion length */ \
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+ 1 /* label length */ \
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+ label_len \
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+ 1 /* context length */ \
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+ context_len )
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#define SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN \
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SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( \
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sizeof(tls1_3_label_prefix) + \
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MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN, \
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MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
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static void ssl_tls1_3_hkdf_encode_label(
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size_t desired_length,
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const unsigned char *label, size_t llen,
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const unsigned char *ctx, size_t clen,
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unsigned char *dst, size_t *dlen )
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{
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size_t total_label_len =
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sizeof(tls1_3_label_prefix) + llen;
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size_t total_hkdf_lbl_len =
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SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( total_label_len, clen );
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unsigned char *p = dst;
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/* Add the size of the expanded key material.
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* We're hardcoding the high byte to 0 here assuming that we never use
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* TLS 1.3 HKDF key expansion to more than 255 Bytes. */
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#if MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN > 255
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#error "The implementation of ssl_tls1_3_hkdf_encode_label() is not fit for the \
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value of MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN"
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#endif
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*p++ = 0;
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*p++ = MBEDTLS_BYTE_0( desired_length );
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/* Add label incl. prefix */
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*p++ = MBEDTLS_BYTE_0( total_label_len );
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memcpy( p, tls1_3_label_prefix, sizeof(tls1_3_label_prefix) );
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p += sizeof(tls1_3_label_prefix);
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memcpy( p, label, llen );
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p += llen;
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/* Add context value */
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*p++ = MBEDTLS_BYTE_0( clen );
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if( clen != 0 )
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memcpy( p, ctx, clen );
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/* Return total length to the caller. */
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*dlen = total_hkdf_lbl_len;
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}
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int mbedtls_ssl_tls1_3_hkdf_expand_label(
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mbedtls_md_type_t hash_alg,
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const unsigned char *secret, size_t slen,
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const unsigned char *label, size_t llen,
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const unsigned char *ctx, size_t clen,
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unsigned char *buf, size_t blen )
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{
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const mbedtls_md_info_t *md;
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unsigned char hkdf_label[ SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN ];
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size_t hkdf_label_len;
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if( llen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN )
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{
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/* Should never happen since this is an internal
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* function, and we know statically which labels
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* are allowed. */
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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}
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if( clen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
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{
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/* Should not happen, as above. */
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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}
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if( blen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN )
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{
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/* Should not happen, as above. */
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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}
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md = mbedtls_md_info_from_type( hash_alg );
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if( md == NULL )
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return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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ssl_tls1_3_hkdf_encode_label( blen,
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label, llen,
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ctx, clen,
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hkdf_label,
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&hkdf_label_len );
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return( mbedtls_hkdf_expand( md,
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secret, slen,
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hkdf_label, hkdf_label_len,
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buf, blen ) );
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}
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/*
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* The traffic keying material is generated from the following inputs:
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*
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* - One secret value per sender.
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* - A purpose value indicating the specific value being generated
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* - The desired lengths of key and IV.
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*
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* The expansion itself is based on HKDF:
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*
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* [sender]_write_key = HKDF-Expand-Label( Secret, "key", "", key_length )
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* [sender]_write_iv = HKDF-Expand-Label( Secret, "iv" , "", iv_length )
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*
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* [sender] denotes the sending side and the Secret value is provided
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* by the function caller. Note that we generate server and client side
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* keys in a single function call.
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*/
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int mbedtls_ssl_tls1_3_make_traffic_keys(
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mbedtls_md_type_t hash_alg,
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const unsigned char *client_secret,
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const unsigned char *server_secret,
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size_t slen, size_t key_len, size_t iv_len,
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mbedtls_ssl_key_set *keys )
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{
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int ret = 0;
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ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
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client_secret, slen,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
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NULL, 0,
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keys->client_write_key, key_len );
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if( ret != 0 )
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return( ret );
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ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
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server_secret, slen,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
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NULL, 0,
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keys->server_write_key, key_len );
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if( ret != 0 )
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return( ret );
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ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
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client_secret, slen,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
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NULL, 0,
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keys->client_write_iv, iv_len );
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if( ret != 0 )
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return( ret );
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ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
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server_secret, slen,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
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NULL, 0,
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keys->server_write_iv, iv_len );
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if( ret != 0 )
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return( ret );
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keys->key_len = key_len;
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keys->iv_len = iv_len;
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return( 0 );
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}
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int mbedtls_ssl_tls1_3_derive_secret(
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mbedtls_md_type_t hash_alg,
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const unsigned char *secret, size_t slen,
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const unsigned char *label, size_t llen,
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const unsigned char *ctx, size_t clen,
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int ctx_hashed,
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unsigned char *dstbuf, size_t buflen )
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{
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int ret;
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unsigned char hashed_context[ MBEDTLS_MD_MAX_SIZE ];
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const mbedtls_md_info_t *md;
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md = mbedtls_md_info_from_type( hash_alg );
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if( md == NULL )
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return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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if( ctx_hashed == MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED )
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{
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ret = mbedtls_md( md, ctx, clen, hashed_context );
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if( ret != 0 )
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return( ret );
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clen = mbedtls_md_get_size( md );
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}
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else
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{
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if( clen > sizeof(hashed_context) )
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{
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/* This should never happen since this function is internal
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* and the code sets `ctx_hashed` correctly.
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* Let's double-check nonetheless to not run at the risk
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* of getting a stack overflow. */
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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}
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memcpy( hashed_context, ctx, clen );
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}
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return( mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
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secret, slen,
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label, llen,
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hashed_context, clen,
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dstbuf, buflen ) );
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}
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int mbedtls_ssl_tls1_3_evolve_secret(
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mbedtls_md_type_t hash_alg,
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const unsigned char *secret_old,
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const unsigned char *input, size_t input_len,
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unsigned char *secret_new )
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{
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int ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
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size_t hlen, ilen;
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unsigned char tmp_secret[ MBEDTLS_MD_MAX_SIZE ] = { 0 };
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unsigned char tmp_input [ MBEDTLS_MD_MAX_SIZE ] = { 0 };
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const mbedtls_md_info_t *md;
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md = mbedtls_md_info_from_type( hash_alg );
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if( md == NULL )
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return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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hlen = mbedtls_md_get_size( md );
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/* For non-initial runs, call Derive-Secret( ., "derived", "")
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* on the old secret. */
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if( secret_old != NULL )
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{
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ret = mbedtls_ssl_tls1_3_derive_secret(
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hash_alg,
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secret_old, hlen,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( derived ),
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NULL, 0, /* context */
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MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED,
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tmp_secret, hlen );
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if( ret != 0 )
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goto cleanup;
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}
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if( input != NULL )
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{
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memcpy( tmp_input, input, input_len );
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ilen = input_len;
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}
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else
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{
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ilen = hlen;
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}
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/* HKDF-Extract takes a salt and input key material.
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* The salt is the old secret, and the input key material
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* is the input secret (PSK / ECDHE). */
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ret = mbedtls_hkdf_extract( md,
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tmp_secret, hlen,
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tmp_input, ilen,
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secret_new );
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if( ret != 0 )
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goto cleanup;
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ret = 0;
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cleanup:
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mbedtls_platform_zeroize( tmp_secret, sizeof(tmp_secret) );
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mbedtls_platform_zeroize( tmp_input, sizeof(tmp_input) );
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return( ret );
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}
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int mbedtls_ssl_tls1_3_derive_early_secrets(
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mbedtls_md_type_t md_type,
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unsigned char const *early_secret,
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unsigned char const *transcript, size_t transcript_len,
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mbedtls_ssl_tls1_3_early_secrets *derived )
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{
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int ret;
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mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
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size_t const md_size = mbedtls_md_get_size( md_info );
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/* We should never call this function with an unknown hash,
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* but add an assertion anyway. */
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if( md_info == 0 )
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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/*
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* 0
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* |
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* v
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* PSK -> HKDF-Extract = Early Secret
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* |
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* +-----> Derive-Secret(., "c e traffic", ClientHello)
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* | = client_early_traffic_secret
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* |
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* +-----> Derive-Secret(., "e exp master", ClientHello)
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* | = early_exporter_master_secret
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* v
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*/
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/* Create client_early_traffic_secret */
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ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
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early_secret, md_size,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( c_e_traffic ),
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transcript, transcript_len,
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MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
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derived->client_early_traffic_secret,
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md_size );
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if( ret != 0 )
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return( ret );
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/* Create early exporter */
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ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
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early_secret, md_size,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( e_exp_master ),
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transcript, transcript_len,
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MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
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derived->early_exporter_master_secret,
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md_size );
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if( ret != 0 )
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return( ret );
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return( 0 );
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}
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int mbedtls_ssl_tls1_3_derive_handshake_secrets(
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mbedtls_md_type_t md_type,
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unsigned char const *handshake_secret,
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unsigned char const *transcript, size_t transcript_len,
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mbedtls_ssl_tls1_3_handshake_secrets *derived )
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{
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int ret;
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mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
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size_t const md_size = mbedtls_md_get_size( md_info );
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|
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/* We should never call this function with an unknown hash,
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* but add an assertion anyway. */
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if( md_info == 0 )
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return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
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|
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/*
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*
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* Handshake Secret
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* |
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* +-----> Derive-Secret( ., "c hs traffic",
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* | ClientHello...ServerHello )
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* | = client_handshake_traffic_secret
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* |
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* +-----> Derive-Secret( ., "s hs traffic",
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* | ClientHello...ServerHello )
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* | = server_handshake_traffic_secret
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*
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*/
|
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|
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/*
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* Compute client_handshake_traffic_secret with
|
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* Derive-Secret( ., "c hs traffic", ClientHello...ServerHello )
|
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*/
|
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ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
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handshake_secret, md_size,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( c_hs_traffic ),
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transcript, transcript_len,
|
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MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
|
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derived->client_handshake_traffic_secret,
|
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md_size );
|
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if( ret != 0 )
|
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return( ret );
|
|
|
|
/*
|
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* Compute server_handshake_traffic_secret with
|
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* Derive-Secret( ., "s hs traffic", ClientHello...ServerHello )
|
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*/
|
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|
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ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
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handshake_secret, md_size,
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MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( s_hs_traffic ),
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transcript, transcript_len,
|
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MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
|
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derived->server_handshake_traffic_secret,
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md_size );
|
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if( ret != 0 )
|
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return( ret );
|
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|
|
return( 0 );
|
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}
|
|
|
|
int mbedtls_ssl_tls1_3_derive_application_secrets(
|
|
mbedtls_md_type_t md_type,
|
|
unsigned char const *application_secret,
|
|
unsigned char const *transcript, size_t transcript_len,
|
|
mbedtls_ssl_tls1_3_application_secrets *derived )
|
|
{
|
|
int ret;
|
|
mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
|
|
size_t const md_size = mbedtls_md_get_size( md_info );
|
|
|
|
/* We should never call this function with an unknown hash,
|
|
* but add an assertion anyway. */
|
|
if( md_info == 0 )
|
|
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_tls1_3_derive_secret( md_type,
|
|
application_secret, md_size,
|
|
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,
|
|
md_size );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
|
|
application_secret, md_size,
|
|
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,
|
|
md_size );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
|
|
application_secret, md_size,
|
|
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( exp_master ),
|
|
transcript, transcript_len,
|
|
MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
|
|
derived->exporter_master_secret,
|
|
md_size );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
/* Generate resumption_master_secret for use with the ticket exchange.
|
|
*
|
|
* This is not integrated with mbedtls_ssl_tls1_3_derive_application_secrets()
|
|
* because it uses the transcript hash up to and including ClientFinished. */
|
|
int mbedtls_ssl_tls1_3_derive_resumption_master_secret(
|
|
mbedtls_md_type_t md_type,
|
|
unsigned char const *application_secret,
|
|
unsigned char const *transcript, size_t transcript_len,
|
|
mbedtls_ssl_tls1_3_application_secrets *derived )
|
|
{
|
|
int ret;
|
|
mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
|
|
size_t const md_size = mbedtls_md_get_size( md_info );
|
|
|
|
/* We should never call this function with an unknown hash,
|
|
* but add an assertion anyway. */
|
|
if( md_info == 0 )
|
|
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
|
|
|
|
ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
|
|
application_secret, md_size,
|
|
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( res_master ),
|
|
transcript, transcript_len,
|
|
MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED,
|
|
derived->resumption_master_secret,
|
|
md_size );
|
|
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
static int ssl_tls1_3_calc_finished_core( mbedtls_md_type_t md_type,
|
|
unsigned char const *base_key,
|
|
unsigned char const *transcript,
|
|
unsigned char *dst )
|
|
{
|
|
const mbedtls_md_info_t* const md_info = mbedtls_md_info_from_type( md_type );
|
|
size_t const md_size = mbedtls_md_get_size( md_info );
|
|
unsigned char finished_key[MBEDTLS_MD_MAX_SIZE];
|
|
int ret;
|
|
|
|
/* We should never call this function with an unknown hash,
|
|
* but add an assertion anyway. */
|
|
if( md_info == 0 )
|
|
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_tls1_3_hkdf_expand_label(
|
|
md_type, base_key, md_size,
|
|
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( finished ),
|
|
NULL, 0,
|
|
finished_key, md_size );
|
|
if( ret != 0 )
|
|
goto exit;
|
|
|
|
ret = mbedtls_md_hmac( md_info, finished_key, md_size, transcript, md_size, dst );
|
|
if( ret != 0 )
|
|
goto exit;
|
|
|
|
exit:
|
|
|
|
mbedtls_platform_zeroize( finished_key, sizeof( finished_key ) );
|
|
return( ret );
|
|
}
|
|
|
|
int mbedtls_ssl_tls1_3_create_psk_binder( mbedtls_ssl_context *ssl,
|
|
const mbedtls_md_type_t md_type,
|
|
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[MBEDTLS_MD_MAX_SIZE];
|
|
unsigned char early_secret[MBEDTLS_MD_MAX_SIZE];
|
|
mbedtls_md_info_t const *md_info = mbedtls_md_info_from_type( md_type );
|
|
size_t const md_size = mbedtls_md_get_size( md_info );
|
|
|
|
#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( md_info == 0 )
|
|
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_tls1_3_evolve_secret( md_type,
|
|
NULL, /* Old secret */
|
|
psk, psk_len, /* Input */
|
|
early_secret );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
|
|
goto exit;
|
|
}
|
|
|
|
if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION )
|
|
{
|
|
ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
|
|
early_secret, md_size,
|
|
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( res_binder ),
|
|
NULL, 0, MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED,
|
|
binder_key, md_size );
|
|
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Derive Early Secret with 'res binder'" ) );
|
|
}
|
|
else
|
|
{
|
|
ret = mbedtls_ssl_tls1_3_derive_secret( md_type,
|
|
early_secret, md_size,
|
|
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( ext_binder ),
|
|
NULL, 0, MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED,
|
|
binder_key, md_size );
|
|
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Derive Early Secret with 'ext binder'" ) );
|
|
}
|
|
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_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_tls1_3_calc_finished_core( md_type, binder_key, transcript, result );
|
|
if( ret != 0 )
|
|
goto exit;
|
|
|
|
MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder", result, md_size );
|
|
|
|
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 */ )
|
|
{
|
|
int ret;
|
|
mbedtls_cipher_info_t const *cipher_info;
|
|
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_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 );
|
|
}
|
|
|
|
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 );
|
|
}
|
|
|
|
#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( ( 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 );
|
|
}
|
|
|
|
/*
|
|
* 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->minor_ver = MBEDTLS_SSL_MINOR_VERSION_4;
|
|
|
|
/* We add the true record content type (1 Byte) to the plaintext and
|
|
* then pad to the configured granularity. The mimimum length of the
|
|
* type-extended and padded plaintext is therefore the padding
|
|
* granularity. */
|
|
transform->minlen =
|
|
transform->taglen + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY;
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
int mbedtls_ssl_tls1_3_key_schedule_stage_early( mbedtls_ssl_context *ssl )
|
|
{
|
|
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
|
|
mbedtls_md_type_t md_type;
|
|
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 );
|
|
}
|
|
|
|
md_type = handshake->ciphersuite_info->mac;
|
|
|
|
ret = mbedtls_ssl_tls1_3_evolve_secret( md_type, NULL, NULL, 0,
|
|
handshake->tls1_3_master_secrets.early );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
|
|
return( ret );
|
|
}
|
|
|
|
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;
|
|
mbedtls_md_info_t const *md_info;
|
|
size_t md_size;
|
|
|
|
unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE];
|
|
size_t transcript_len;
|
|
|
|
mbedtls_cipher_info_t const *cipher_info;
|
|
size_t keylen, ivlen;
|
|
|
|
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
|
|
const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info;
|
|
mbedtls_ssl_tls1_3_handshake_secrets *tls13_hs_secrets = &handshake->tls13_hs_secrets;
|
|
|
|
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_tls13_generate_handshake_keys" ) );
|
|
|
|
cipher_info = mbedtls_cipher_info_from_type( ciphersuite_info->cipher );
|
|
keylen = cipher_info->key_bitlen >> 3;
|
|
ivlen = cipher_info->iv_size;
|
|
|
|
md_type = ciphersuite_info->mac;
|
|
md_info = mbedtls_md_info_from_type( md_type );
|
|
md_size = mbedtls_md_get_size( md_info );
|
|
|
|
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_tls1_3_derive_handshake_secrets( md_type,
|
|
handshake->tls1_3_master_secrets.handshake,
|
|
transcript, transcript_len, tls13_hs_secrets );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_derive_handshake_secrets",
|
|
ret );
|
|
return( ret );
|
|
}
|
|
|
|
MBEDTLS_SSL_DEBUG_BUF( 4, "Client handshake traffic secret",
|
|
tls13_hs_secrets->client_handshake_traffic_secret,
|
|
md_size );
|
|
MBEDTLS_SSL_DEBUG_BUF( 4, "Server handshake traffic secret",
|
|
tls13_hs_secrets->server_handshake_traffic_secret,
|
|
md_size );
|
|
|
|
/*
|
|
* Export client handshake traffic secret
|
|
*/
|
|
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
|
|
if( ssl->f_export_keys != NULL )
|
|
{
|
|
ssl->f_export_keys( ssl->p_export_keys,
|
|
MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_HANDSHAKE_TRAFFIC_SECRET,
|
|
tls13_hs_secrets->client_handshake_traffic_secret,
|
|
md_size,
|
|
handshake->randbytes + 32,
|
|
handshake->randbytes,
|
|
MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ );
|
|
|
|
ssl->f_export_keys( ssl->p_export_keys,
|
|
MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_HANDSHAKE_TRAFFIC_SECRET,
|
|
tls13_hs_secrets->server_handshake_traffic_secret,
|
|
md_size,
|
|
handshake->randbytes + 32,
|
|
handshake->randbytes,
|
|
MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ );
|
|
}
|
|
#endif /* MBEDTLS_SSL_EXPORT_KEYS */
|
|
|
|
ret = mbedtls_ssl_tls1_3_make_traffic_keys( md_type,
|
|
tls13_hs_secrets->client_handshake_traffic_secret,
|
|
tls13_hs_secrets->server_handshake_traffic_secret,
|
|
md_size, keylen, ivlen, traffic_keys );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_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;
|
|
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
|
|
mbedtls_md_type_t const md_type = handshake->ciphersuite_info->mac;
|
|
size_t ephemeral_len = 0;
|
|
unsigned char ecdhe[MBEDTLS_ECP_MAX_BYTES];
|
|
#if defined(MBEDTLS_DEBUG_C)
|
|
mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
|
|
size_t const md_size = mbedtls_md_get_size( md_info );
|
|
#endif /* MBEDTLS_DEBUG_C */
|
|
|
|
#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_tls1_3_ephemeral_enabled( ssl ) )
|
|
{
|
|
if( mbedtls_ssl_tls13_named_group_is_ecdhe( handshake->offered_group_id ) )
|
|
{
|
|
#if defined(MBEDTLS_ECDH_C)
|
|
ret = mbedtls_ecdh_calc_secret( &handshake->ecdh_ctx,
|
|
&ephemeral_len, ecdhe, sizeof( ecdhe ),
|
|
ssl->conf->f_rng,
|
|
ssl->conf->p_rng );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
|
|
return( ret );
|
|
}
|
|
#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_tls1_3_evolve_secret( md_type,
|
|
handshake->tls1_3_master_secrets.early,
|
|
ecdhe, ephemeral_len,
|
|
handshake->tls1_3_master_secrets.handshake );
|
|
if( ret != 0 )
|
|
{
|
|
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
|
|
return( ret );
|
|
}
|
|
|
|
MBEDTLS_SSL_DEBUG_BUF( 4, "Handshake secret",
|
|
handshake->tls1_3_master_secrets.handshake, md_size );
|
|
|
|
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED)
|
|
mbedtls_platform_zeroize( ecdhe, sizeof( ecdhe ) );
|
|
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */
|
|
return( 0 );
|
|
}
|
|
|
|
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
|