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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
* Copyright (c) 2025-present Eclipse ThreadX Contributors
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** Transport Layer Security (TLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_tls.h"
#ifdef NX_SECURE_ENABLE_DTLS
#include "nx_secure_dtls.h"
#endif /* NX_SECURE_ENABLE_DTLS */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_1_3_finished_hash_generate PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function generates the Finished message hash using the hash */
/* data collected in the TLS session control block during the */
/* handshake. TLS 1.3 uses a different construction for the finished */
/* hash separate from the earlier versions. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* is_server Non-zero for server hash */
/* hash_size Return the size of the hash */
/* finished_hash Pointer to hash output buffer */
/* available_size Available size of buffer */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* [nx_crypto_init] Initialize crypto */
/* [nx_crypto_operation] Crypto operation */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_send_finished Send Finished message */
/* _nx_secure_tls_process_finished Process Finished message */
/* */
/**************************************************************************/
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
UINT _nx_secure_tls_1_3_finished_hash_generate(NX_SECURE_TLS_SESSION *tls_session,
UINT is_server, UINT *hash_size, UCHAR *finished_hash,
ULONG available_size)
{
UINT status;
const NX_CRYPTO_METHOD *hmac_method = NX_NULL;
const NX_CRYPTO_METHOD *hash_method = NX_NULL;
CHAR *metadata = NX_NULL;
UINT metadata_size;
VOID *handler = NX_NULL;
UCHAR *finished_key = NX_NULL;
UINT finished_key_len;
//UINT hash_index;
UCHAR *transcript_hash;
NX_SECURE_TLS_KEY_SECRETS *secrets;
/* We need to extract the Finished hash and verify that the handshake to this point
has not been corrupted or tampered with. */
/* From the RFC 8446 (TLS 1.3):
finished_key = HKDF-Expand-Label(BaseKey, "finished", "", Hash.length)
Structure of this message:
struct {
opaque verify_data[Hash.length];
} Finished;
The verify_data value is computed as follows:
verify_data =
HMAC(finished_key,
Transcript-Hash(Handshake Context,
Certificate*, CertificateVerify*))
*/
if (tls_session -> nx_secure_tls_session_ciphersuite == NX_NULL)
{
return(NX_SECURE_TLS_UNKNOWN_CIPHERSUITE);
}
if (available_size < tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash_size)
{
/* Packet buffer too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
/* Get our generated secrets. */
secrets = &tls_session->nx_secure_tls_key_material.nx_secure_tls_key_secrets;
/* Get our HMAC and hash methods. */
hash_method = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash;
hmac_method = tls_session -> nx_secure_tls_crypto_table->nx_secure_tls_hmac_method;
*hash_size = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash_size;
/* Get our Finished Hash metadata space. */
metadata = tls_session -> nx_secure_tls_handshake_hash.nx_secure_tls_handshake_hash_scratch;
metadata_size = tls_session -> nx_secure_tls_handshake_hash.nx_secure_tls_handshake_hash_scratch_size;
/* Now select the finished key (generated in _nx_secure_tls_1_3_generate_keys) based on the current request. */
if(is_server)
{
finished_key = secrets->tls_server_finished_key;
finished_key_len = secrets->tls_server_finished_key_len;
}
else
{
/* Client. */
finished_key = secrets->tls_client_finished_key;
finished_key_len = secrets->tls_client_finished_key_len;
}
/* Get the transcript hash context up to now - Server Finished received for Client, all messages before Finished sent for Server. */
transcript_hash = tls_session->nx_secure_tls_key_material.nx_secure_tls_transcript_hashes[NX_SECURE_TLS_TRANSCRIPT_IDX_SERVER_FINISHED];
/* Initialize HMAC. */
if (hash_method -> nx_crypto_init)
{
status = hmac_method -> nx_crypto_init((NX_CRYPTO_METHOD*)hmac_method,
finished_key,
(finished_key_len << 3),
handler,
metadata,
metadata_size);
if (status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
/* Initialize HMAC with our hash method. */
status = hmac_method->nx_crypto_operation(NX_CRYPTO_HMAC_SET_HASH, NX_NULL, (NX_CRYPTO_METHOD*)hash_method, NX_NULL, 0, NX_NULL, 0,
NX_NULL, NX_NULL, 0, metadata, metadata_size, NX_NULL, NX_NULL);
if (status != NX_CRYPTO_SUCCESS)
{
return(status);
}
if (hmac_method -> nx_crypto_operation != NX_NULL)
{
status = hmac_method -> nx_crypto_operation(NX_CRYPTO_HASH_INITIALIZE,
handler,
(NX_CRYPTO_METHOD*)hmac_method,
finished_key,
(NX_CRYPTO_KEY_SIZE)(finished_key_len << 3),
NX_NULL,
0,
NX_NULL,
NX_NULL,
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if (status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
/* Update the HMAC with the transcript hash context. */
if (hmac_method -> nx_crypto_operation != NX_NULL)
{
status = hmac_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
handler,
(NX_CRYPTO_METHOD*)hmac_method,
NX_NULL, /* Key. */
0,
transcript_hash, /* Input. */
*hash_size,
NX_NULL,
NX_NULL, /* output */
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if (status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
/* Finally, calculate the Finished hash data. */
if (hmac_method -> nx_crypto_operation != NX_NULL)
{
status = hmac_method -> nx_crypto_operation(NX_CRYPTO_HASH_CALCULATE,
handler,
(NX_CRYPTO_METHOD*)hmac_method,
NX_NULL,
0,
NX_NULL,
0,
NX_NULL,
finished_hash,
*hash_size,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if (status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
else
{
return(NX_SECURE_TLS_MISSING_CRYPTO_ROUTINE);
}
return(NX_SUCCESS);
}
#endif
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