#include "api.h"
#include "niederreiter.h"
#include "randombytes.h"
#include "rng.h"

#include <string.h>

/* Generates a keypair - pk is the public key and sk is the secret key. */
int PQCLEAN_LEDAKEMLT12_CLEAN_crypto_kem_keypair(unsigned char *pk, unsigned char *sk) {
    AES_XOF_struct niederreiter_keys_expander;
    randombytes(((privateKeyNiederreiter_t *)sk)->prng_seed, TRNG_BYTE_LENGTH);
    PQCLEAN_LEDAKEMLT12_CLEAN_seedexpander_from_trng(&niederreiter_keys_expander,
            ((privateKeyNiederreiter_t *)sk)->prng_seed);
    PQCLEAN_LEDAKEMLT12_CLEAN_niederreiter_keygen((publicKeyNiederreiter_t *) pk,
            (privateKeyNiederreiter_t *) sk,
            &niederreiter_keys_expander);
    return 0;
}

/* Encrypt - pk is the public key, ct is a key encapsulation message
  (ciphertext), ss is the shared secret.*/
int PQCLEAN_LEDAKEMLT12_CLEAN_crypto_kem_enc( unsigned char *ct, unsigned char *ss, const unsigned char *pk) {
    AES_XOF_struct niederreiter_encap_key_expander;
    unsigned char encapsulated_key_seed[TRNG_BYTE_LENGTH];
    DIGIT error_vector[N0 * NUM_DIGITS_GF2X_ELEMENT];

    randombytes(encapsulated_key_seed, TRNG_BYTE_LENGTH);
    PQCLEAN_LEDAKEMLT12_CLEAN_seedexpander_from_trng(&niederreiter_encap_key_expander, encapsulated_key_seed);

    PQCLEAN_LEDAKEMLT12_CLEAN_rand_circulant_blocks_sequence(error_vector, &niederreiter_encap_key_expander);

    HASH_FUNCTION(ss, (const uint8_t *) error_vector, (N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B));

    PQCLEAN_LEDAKEMLT12_CLEAN_niederreiter_encrypt((DIGIT *) ct, (publicKeyNiederreiter_t *) pk, error_vector);
    return 0;
}


/* Decrypt - ct is a key encapsulation message (ciphertext), sk is the private
   key, ss is the shared secret */
int PQCLEAN_LEDAKEMLT12_CLEAN_crypto_kem_dec(unsigned char *ss,
        const unsigned char *ct,
        const unsigned char *sk ) {
    DIGIT decoded_error_vector[N0 * NUM_DIGITS_GF2X_ELEMENT];

    PQCLEAN_LEDAKEMLT12_CLEAN_niederreiter_decrypt(decoded_error_vector,
            (privateKeyNiederreiter_t *)sk,
            (DIGIT *)ct);
    HASH_FUNCTION(ss, (const unsigned char *) decoded_error_vector, (N0 * NUM_DIGITS_GF2X_ELEMENT * DIGIT_SIZE_B));

    return 0;
}