kem.c

#include "api.h"
#include "indcpa.h"
#include "kem.h"
#include "params.h"
#include "randombytes.h"
#include "symmetric.h"
#include "verify.h"
#include <stdint.h>
#include <string.h>

int PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_keypair_derand(uint8_t *pk, uint8_t *sk, const uint8_t *coins) {
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_indcpa_keypair_derand(pk, sk, coins);
    memcpy(sk + RUDRAKSH_SK_Z_OFFSET, coins + 2u * RUDRAKSH_SYMBYTES, RUDRAKSH_SYMBYTES);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_hash_h(sk + RUDRAKSH_SK_PKH_OFFSET, pk, RUDRAKSH_PUBLICKEYBYTES);
    memcpy(sk + RUDRAKSH_SK_PK_OFFSET, pk, RUDRAKSH_PUBLICKEYBYTES);
    return 0;
}

int PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_keypair(uint8_t *pk, uint8_t *sk) {
    uint8_t coins[3u * RUDRAKSH_SYMBYTES];

    randombytes(coins, sizeof coins);
    return PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_keypair_derand(pk, sk, coins);
}

int PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_enc_derand(uint8_t *ct, uint8_t *ss, const uint8_t *pk, const uint8_t *coins) {
    uint8_t buf[2u * RUDRAKSH_SYMBYTES];
    uint8_t kr[2u * RUDRAKSH_SYMBYTES];

    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_hash_h(buf, pk, RUDRAKSH_PUBLICKEYBYTES);
    memcpy(buf + RUDRAKSH_SYMBYTES, coins, RUDRAKSH_SYMBYTES);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_hash_g(kr, buf, sizeof buf);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_indcpa_enc(ct, coins, pk, kr + RUDRAKSH_SYMBYTES);
    memcpy(ss, kr, RUDRAKSH_SSBYTES);
    return 0;
}

int PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_enc(uint8_t *ct, uint8_t *ss, const uint8_t *pk) {
    uint8_t coins[RUDRAKSH_SYMBYTES];

    randombytes(coins, sizeof coins);
    return PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_enc_derand(ct, ss, pk, coins);
}

int PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_crypto_kem_dec(uint8_t *ss, const uint8_t *ct, const uint8_t *sk) {
    int fail;
    uint8_t msg[RUDRAKSH_MSGBYTES];
    uint8_t buf[2u * RUDRAKSH_SYMBYTES];
    uint8_t kr[2u * RUDRAKSH_SYMBYTES];
    uint8_t cmp[RUDRAKSH_CIPHERTEXTBYTES];
    uint8_t reject[RUDRAKSH_SSBYTES];
    const uint8_t *pk = sk + RUDRAKSH_SK_PK_OFFSET;

    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_indcpa_dec(msg, ct, sk);

    memcpy(buf, sk + RUDRAKSH_SK_PKH_OFFSET, RUDRAKSH_SYMBYTES);
    memcpy(buf + RUDRAKSH_SYMBYTES, msg, RUDRAKSH_MSGBYTES);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_hash_g(kr, buf, sizeof buf);

    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_indcpa_enc(cmp, msg, pk, kr + RUDRAKSH_SYMBYTES);
    fail = PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_verify(ct, cmp, RUDRAKSH_CIPHERTEXTBYTES);

    memcpy(ss, kr, RUDRAKSH_SSBYTES);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_rkprf(reject, ct, sk + RUDRAKSH_SK_Z_OFFSET);
    PQCLEAN_RUDRAKSHKEMPOLY64_CLEAN_cmov(ss, reject, RUDRAKSH_SSBYTES, (uint8_t)fail);

    return 0;
}