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pqcrypto/crypto_kem/kyber768-90s/avx2/kem.c
John M. Schanck 127e9ec326 Round 3 Kyber
2021-03-24 21:02:49 +00:00

127 lines
4.9 KiB
C

#include "indcpa.h"
#include "kem.h"
#include "params.h"
#include "randombytes.h"
#include "symmetric.h"
#include "verify.h"
#include <stddef.h>
#include <stdint.h>
/*************************************************
* Name: PQCLEAN_KYBER76890S_AVX2_crypto_kem_keypair
*
* Description: Generates public and private key
* for CCA-secure Kyber key encapsulation mechanism
*
* Arguments: - unsigned char *pk: pointer to output public key
* (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
* - unsigned char *sk: pointer to output private key
* (an already allocated array of KYBER_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_KYBER76890S_AVX2_crypto_kem_keypair(unsigned char pk[KYBER_PUBLICKEYBYTES],
unsigned char sk[KYBER_SECRETKEYBYTES]) {
size_t i;
PQCLEAN_KYBER76890S_AVX2_indcpa_keypair(pk, sk);
for (i = 0; i < KYBER_INDCPA_PUBLICKEYBYTES; i++) {
sk[i + KYBER_INDCPA_SECRETKEYBYTES] = pk[i];
}
hash_h(sk + KYBER_SECRETKEYBYTES - 2 * KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
/* Value z for pseudo-random output on reject */
randombytes(sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES);
return 0;
}
/*************************************************
* Name: PQCLEAN_KYBER76890S_AVX2_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 KYBER_CIPHERTEXTBYTES bytes)
* - unsigned char *ss: pointer to output shared secret
* (an already allocated array of KYBER_SSBYTES bytes)
* - const unsigned char *pk: pointer to input public key
* (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_KYBER76890S_AVX2_crypto_kem_enc(unsigned char ct[KYBER_CIPHERTEXTBYTES],
unsigned char ss[KYBER_SSBYTES],
const unsigned char pk[KYBER_PUBLICKEYBYTES]) {
uint8_t buf[2 * KYBER_SYMBYTES];
/* Will contain key, coins */
uint8_t kr[2 * KYBER_SYMBYTES];
randombytes(buf, KYBER_SYMBYTES);
/* Don't release system RNG output */
hash_h(buf, buf, KYBER_SYMBYTES);
/* Multitarget countermeasure for coins + contributory KEM */
hash_h(buf + KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
hash_g(kr, buf, 2 * KYBER_SYMBYTES);
/* coins are in kr+KYBER_SYMBYTES */
PQCLEAN_KYBER76890S_AVX2_indcpa_enc(ct, buf, pk, kr + KYBER_SYMBYTES);
/* overwrite coins in kr with H(c) */
hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES);
/* hash concatenation of pre-k and H(c) to k */
kdf(ss, kr, 2 * KYBER_SYMBYTES);
return 0;
}
/*************************************************
* Name: PQCLEAN_KYBER76890S_AVX2_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 KYBER_SSBYTES bytes)
* - const unsigned char *ct: pointer to input cipher text
* (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
* - const unsigned char *sk: pointer to input private key
* (an already allocated array of KYBER_SECRETKEYBYTES bytes)
*
* Returns 0.
*
* On failure, ss will contain a pseudo-random value.
**************************************************/
int PQCLEAN_KYBER76890S_AVX2_crypto_kem_dec(unsigned char ss[KYBER_SSBYTES],
const unsigned char ct[KYBER_CIPHERTEXTBYTES],
const unsigned char sk[KYBER_SECRETKEYBYTES]) {
size_t i;
int fail;
uint8_t buf[2 * KYBER_SYMBYTES];
/* Will contain key, coins */
uint8_t kr[2 * KYBER_SYMBYTES];
ALIGNED_UINT8(KYBER_CIPHERTEXTBYTES) cmp;
const uint8_t *pk = sk + KYBER_INDCPA_SECRETKEYBYTES;
PQCLEAN_KYBER76890S_AVX2_indcpa_dec(buf, ct, sk);
/* Multitarget countermeasure for coins + contributory KEM */
for (i = 0; i < KYBER_SYMBYTES; i++) {
buf[KYBER_SYMBYTES + i] = sk[KYBER_SECRETKEYBYTES - 2 * KYBER_SYMBYTES + i];
}
hash_g(kr, buf, 2 * KYBER_SYMBYTES);
/* coins are in kr+KYBER_SYMBYTES */
PQCLEAN_KYBER76890S_AVX2_indcpa_enc(cmp.coeffs, buf, pk, kr + KYBER_SYMBYTES);
fail = PQCLEAN_KYBER76890S_AVX2_verify(ct, cmp.coeffs, KYBER_CIPHERTEXTBYTES);
/* overwrite coins in kr with H(c) */
hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES);
/* Overwrite pre-k with z on re-encryption failure */
PQCLEAN_KYBER76890S_AVX2_cmov(kr, sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES, fail);
/* hash concatenation of pre-k and H(c) to k */
kdf(ss, kr, 2 * KYBER_SYMBYTES);
return 0;
}