transport.h

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/* 2025-2026 Quantum Resistant Cryptographic Solutions Corporation
 * All Rights Reserved.
 *
 * NOTICE:
 * This software and all accompanying materials are the exclusive property of
 * Quantum Resistant Cryptographic Solutions Corporation (QRCS). The intellectual
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 *
 * CRYPTOGRAPHIC ALGORITHMS AND IMPLEMENTATIONS:
 * - This software includes implementations of cryptographic primitives and
 *   algorithms that are standardized or in the public domain, such as AES
 *   and SHA-3, which are not proprietary to QRCS.
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 *   algorithms designed by QRCS, including but not limited to RCS, SCB, CSX, QMAC, and
 *   related components, which are proprietary to QRCS.
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 *   Public Research and Evaluation License (QRCS-PREL), 2025-2026.
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 * EXPERIMENTAL CRYPTOGRAPHY NOTICE:
 * Portions of this software may include experimental, novel, or evolving
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 * ARISING FROM THE USE OR MISUSE OF THIS SOFTWARE.
 *
 * FULL LICENSE:
 * This software is subject to the Quantum Resistant Cryptographic Solutions
 * Public Research and Evaluation License (QRCS-PREL), 2025-2026. The complete license terms
 * are provided in the accompanying LICENSE file or at https://www.qrcscorp.ca.
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 * Written by: John G. Underhill
 * Contact: contact@qrcscorp.ca
 */
 
#ifndef UDIF_TRANSPORT_H
#define UDIF_TRANSPORT_H
 
#include "udif.h"
#include "certificate.h"

 
static const char UDIF_TRANSPORT_CUSTOM[] = "UDIF:HS-MAC:V1";
 
/* === Session Management === */

UDIF_EXPORT_API typedef struct udif_session_state
{
    qsc_rcs_state txcpr;                        
    qsc_rcs_state rxcpr;                        
    uint64_t txseq;                             
    uint64_t rxseq;                             
    uint64_t epoch;                             
    uint64_t last_ratchet;                      
    uint8_t local_serial[UDIF_CERTIFICATE_SERIAL_SIZE];     
    uint8_t remote_serial[UDIF_CERTIFICATE_SERIAL_SIZE];    
    uint8_t session_id[UDIF_CRYPTO_HASH_SIZE];       
    uint8_t ratchet_state[UDIF_CRYPTO_HASH_SIZE];    
    bool established;                           
    bool initiator;                             
    /* Handshake state (only used during handshake, cleared after) */
    struct {
        uint8_t local_kem_sk[UDIF_KEM_PRIVATEKEY_SIZE];  
        uint8_t kem_ss[UDIF_KEM_SECRET_SIZE];            
        uint8_t nonce_local[32U];                        
        uint8_t nonce_remote[32U];                       
        uint8_t transcript[4096U];                       
        size_t transcript_len;                           
        bool in_progress;                                
    } handshake;
} udif_session_state;

UDIF_EXPORT_API void udif_session_initialize(udif_session_state* session);

UDIF_EXPORT_API udif_errors udif_session_handshake_init(udif_session_state* session, udif_network_packet* packet, const udif_child_certificate* local_cert, const uint8_t local_privkey[UDIF_ASYMMETRIC_SIGNING_KEY_SIZE], 
    const uint8_t local_serial[UDIF_CERTIFICATE_SERIAL_SIZE], const uint8_t remote_serial[UDIF_CERTIFICATE_SERIAL_SIZE], bool (*rng_generate)(uint8_t*, size_t));

UDIF_EXPORT_API udif_errors udif_session_handshake_resp(udif_session_state* session, udif_network_packet* packet, const udif_network_packet* init_packet,
    const udif_child_certificate* local_cert, const uint8_t local_privkey[UDIF_ASYMMETRIC_SIGNING_KEY_SIZE], const uint8_t local_serial[UDIF_CERTIFICATE_SERIAL_SIZE], 
    const udif_child_certificate* remote_cert, bool (*rng_generate)(uint8_t*, size_t));

UDIF_EXPORT_API udif_errors udif_session_handshake_confirm(udif_session_state* session, udif_network_packet* packet, 
    const udif_network_packet* resp_packet, const udif_child_certificate* remote_cert);

UDIF_EXPORT_API udif_errors udif_session_handshake_finish(udif_session_state* session, udif_network_packet* packet, const udif_network_packet* confirm_packet);
 
/* === Data Encryption === */

UDIF_EXPORT_API udif_errors udif_session_encrypt(udif_session_state* session, udif_network_packet* packet, const uint8_t* plaintext, size_t plntextlen);

UDIF_EXPORT_API udif_errors udif_session_decrypt(udif_session_state* session, uint8_t* plaintext, size_t* plntextlen, const udif_network_packet* packet);
 
/* === Forward Secrecy === */

UDIF_EXPORT_API udif_errors udif_session_ratchet(udif_session_state* session, udif_network_packet* packetout, const udif_network_packet* packetin, bool (*rng_generate)(uint8_t*, size_t));

UDIF_EXPORT_API bool udif_session_needs_ratchet(const udif_session_state* session, uint64_t currtime);
 
/* === Session State === */

UDIF_EXPORT_API void udif_session_dispose(udif_session_state* session);

UDIF_EXPORT_API void udif_session_clear(udif_session_state* session);

UDIF_EXPORT_API bool udif_session_is_established(const udif_session_state* session);

UDIF_EXPORT_API udif_errors udif_session_get_statistics(const udif_session_state* session, uint64_t* txseq, uint64_t* rxseq, uint64_t* epoch);
 
/* === Packet Operations === */

UDIF_EXPORT_API udif_errors udif_packet_serialize(uint8_t* stream, size_t* streamlen, const udif_network_packet* packet);

UDIF_EXPORT_API udif_errors udif_packet_deserialize(udif_network_packet* packet, const uint8_t* stream, size_t streamlen);

UDIF_EXPORT_API udif_errors udif_packet_validate(const udif_session_state* session, const udif_network_packet* packet, uint8_t expected_flag);

UDIF_EXPORT_API void udif_packet_set_time(udif_network_packet* packet, uint64_t currtime);

UDIF_EXPORT_API bool udif_packet_is_fresh(const udif_network_packet* packet, uint64_t currtime);

UDIF_EXPORT_API void udif_packet_clear(udif_network_packet* packet);
 
#endif