pqc/crypto_kem/newhope512cpa/clean/kem.c

#include "api.h"
#include "cpapke.h"
#include "fips202.h"
#include "params.h"
#include "randombytes.h"
#include "verify.h"
#include <string.h>

/*************************************************
* Name:        crypto_kem_keypair
*
* Description: Generates public and private key
*              for CCA secure NewHope key encapsulation
*              mechanism
*
* Arguments:   - unsigned char *pk: pointer to output public key (an already allocated array of CRYPTO_PUBLICKEYBYTES bytes)
*              - unsigned char *sk: pointer to output private key (an already allocated array of CRYPTO_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_NEWHOPE512CPA_CLEAN_crypto_kem_keypair(unsigned char *pk, unsigned char *sk) {
    PQCLEAN_NEWHOPE512CPA_CLEAN_cpapke_keypair(pk, sk);                                                        /* First put the actual secret key into sk */

    return 0;
}

/*************************************************
* Name:        crypto_kem_enc
*
* Description: Generates cipher text and shared
*              secret for given public key
*
* Arguments:   - unsigned char *ct:       pointer to output cipher text (an already allocated array of CRYPTO_CIPHERTEXTBYTES bytes)
*              - unsigned char *ss:       pointer to output shared secret (an already allocated array of CRYPTO_BYTES bytes)
*              - const unsigned char *pk: pointer to input public key (an already allocated array of CRYPTO_PUBLICKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_NEWHOPE512CPA_CLEAN_crypto_kem_enc(unsigned char *ct, unsigned char *ss, const unsigned char *pk) {
    unsigned char buf[2 * NEWHOPE_SYMBYTES];

    buf[0] = 0x02;
    randombytes(buf + 1, NEWHOPE_SYMBYTES);

    shake256(buf, 2 * NEWHOPE_SYMBYTES, buf, NEWHOPE_SYMBYTES + 1);                    /* Don't release system RNG output */

    PQCLEAN_NEWHOPE512CPA_CLEAN_cpapke_enc(ct, buf, pk, buf + NEWHOPE_SYMBYTES);                               /* coins are in buf+NEWHOPE_SYMBYTES */

    shake256(ss, NEWHOPE_SYMBYTES, buf, NEWHOPE_SYMBYTES);                         /* hash pre-k to ss */
    return 0;
}


/*************************************************
* Name:        crypto_kem_dec
*
* Description: Generates shared secret for given
*              cipher text and private key
*
* Arguments:   - unsigned char *ss:       pointer to output shared secret (an already allocated array of CRYPTO_BYTES bytes)
*              - const unsigned char *ct: pointer to input cipher text (an already allocated array of CRYPTO_CIPHERTEXTBYTES bytes)
*              - const unsigned char *sk: pointer to input private key (an already allocated array of CRYPTO_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_NEWHOPE512CPA_CLEAN_crypto_kem_dec(unsigned char *ss, const unsigned char *ct, const unsigned char *sk) {
    PQCLEAN_NEWHOPE512CPA_CLEAN_cpapke_dec(ss, ct, sk);

    shake256(ss, NEWHOPE_SYMBYTES, ss, NEWHOPE_SYMBYTES);                          /* hash pre-k to ss */

    return 0;
}