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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** Transport Layer Security (TLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_tls.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_record_hash_initialize PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function initializes a hash method for generating a MAC for */
/* a TLS message during the encrypted portion of the TLS handshake and */
/* session. The hashing must be done in pieces to support the packet */
/* chaining feature of NX_PACKET. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* sequence_num Record sequence number */
/* header Record header */
/* header_length Length of record header */
/* hash_length Length of hash */
/* mac_secret Key used for MAC generation */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* [nx_crypto_operation] Crypto operation */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_send_record Send the TLS record */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _nx_secure_tls_record_hash_initialize(NX_SECURE_TLS_SESSION *tls_session,
ULONG sequence_num[NX_SECURE_TLS_SEQUENCE_NUMBER_SIZE],
UCHAR *header, UINT header_length, UINT *hash_length,
UCHAR *mac_secret)
{
UINT status;
const NX_CRYPTO_METHOD *authentication_method;
UINT hash_size;
UCHAR adjusted_sequence_num[8];
/* We need to generate a Message Authentication Code (MAC) for each record during an "active" TLS session
(following a ChangeCipherSpec message). The hash algorithm is determined by the ciphersuite, and HMAC
is used with that hash algorithm to protect the TLS record contents from tampering.
The MAC is generated as:
HMAC_hash(MAC_write_secret, seq_num + type + version + length + data);
*/
if (tls_session -> nx_secure_tls_session_ciphersuite == NX_NULL)
{
/* Likely internal error since at this point ciphersuite negotiation was theoretically completed. */
return(NX_SECURE_TLS_UNKNOWN_CIPHERSUITE);
}
/* Get our authentication method from the ciphersuite. */
authentication_method = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash;
/* Assert that we have an authentication mechanism. */
NX_ASSERT(authentication_method -> nx_crypto_operation != NX_NULL);
/* Get the hash size and MAC secret for our current session. */
hash_size = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash_size;
/* Correct the endianness of our sequence number before hashing. */
adjusted_sequence_num[0] = (UCHAR)(sequence_num[1] >> 24);
adjusted_sequence_num[1] = (UCHAR)(sequence_num[1] >> 16);
adjusted_sequence_num[2] = (UCHAR)(sequence_num[1] >> 8);
adjusted_sequence_num[3] = (UCHAR)(sequence_num[1]);
adjusted_sequence_num[4] = (UCHAR)(sequence_num[0] >> 24);
adjusted_sequence_num[5] = (UCHAR)(sequence_num[0] >> 16);
adjusted_sequence_num[6] = (UCHAR)(sequence_num[0] >> 8);
adjusted_sequence_num[7] = (UCHAR)(sequence_num[0]);
if (authentication_method -> nx_crypto_init)
{
status = authentication_method -> nx_crypto_init((NX_CRYPTO_METHOD*)authentication_method,
mac_secret,
(NX_CRYPTO_KEY_SIZE)(hash_size << 3),
&tls_session -> nx_secure_hash_mac_handler,
tls_session -> nx_secure_hash_mac_metadata_area,
tls_session -> nx_secure_hash_mac_metadata_size);
if (status != NX_SUCCESS)
{
return(status);
}
}
/* Call the initialization routine for our hash method. */
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_INITIALIZE,
tls_session -> nx_secure_hash_mac_handler,
(NX_CRYPTO_METHOD*)authentication_method,
mac_secret,
(NX_CRYPTO_KEY_SIZE)(hash_size << 3),
NX_NULL,
0,
NX_NULL,
NX_NULL,
0,
tls_session -> nx_secure_hash_mac_metadata_area,
tls_session -> nx_secure_hash_mac_metadata_size,
NX_NULL,
NX_NULL);
/* Check for error in encryption routine. */
if (status != NX_SUCCESS)
{
return(status);
}
/* Update the hash with the sequence number. */
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
tls_session -> nx_secure_hash_mac_handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
adjusted_sequence_num,
8,
NX_NULL,
NX_NULL,
0,
tls_session -> nx_secure_hash_mac_metadata_area,
tls_session -> nx_secure_hash_mac_metadata_size,
NX_NULL,
NX_NULL);
/* Check for error in encryption routine. */
if (status != NX_SUCCESS)
{
return(status);
}
#ifdef NX_SECURE_KEY_CLEAR
NX_SECURE_MEMSET(adjusted_sequence_num, 0, sizeof(adjusted_sequence_num));
#endif /* NX_SECURE_KEY_CLEAR */
/* Update the hash with the record header. */
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
tls_session -> nx_secure_hash_mac_handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
header,
header_length,
NX_NULL,
NX_NULL,
0,
tls_session -> nx_secure_hash_mac_metadata_area,
tls_session -> nx_secure_hash_mac_metadata_size,
NX_NULL,
NX_NULL);
/* Return how many bytes our hash is since the caller doesn't necessarily know. */
*hash_length = hash_size;
return(status);
}