127 lines
4.8 KiB
C
127 lines
4.8 KiB
C
#include "indcpa.h"
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#include "kem.h"
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#include "params.h"
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#include "randombytes.h"
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#include "symmetric.h"
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#include "verify.h"
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#include <stddef.h>
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#include <stdint.h>
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/*************************************************
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* Name: PQCLEAN_KYBER768_CLEAN_crypto_kem_keypair
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*
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* Description: Generates public and private key
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* for CCA-secure Kyber key encapsulation mechanism
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*
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* Arguments: - unsigned char *pk: pointer to output public key
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* (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
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* - unsigned char *sk: pointer to output private key
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* (an already allocated array of KYBER_SECRETKEYBYTES bytes)
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*
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* Returns 0 (success)
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**************************************************/
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int PQCLEAN_KYBER768_CLEAN_crypto_kem_keypair(unsigned char pk[KYBER_PUBLICKEYBYTES],
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unsigned char sk[KYBER_SECRETKEYBYTES]) {
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size_t i;
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PQCLEAN_KYBER768_CLEAN_indcpa_keypair(pk, sk);
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for (i = 0; i < KYBER_INDCPA_PUBLICKEYBYTES; i++) {
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sk[i + KYBER_INDCPA_SECRETKEYBYTES] = pk[i];
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}
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hash_h(sk + KYBER_SECRETKEYBYTES - 2 * KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
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/* Value z for pseudo-random output on reject */
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randombytes(sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES);
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return 0;
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}
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/*************************************************
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* Name: PQCLEAN_KYBER768_CLEAN_crypto_kem_enc
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*
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* Description: Generates cipher text and shared
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* secret for given public key
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*
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* Arguments: - unsigned char *ct: pointer to output cipher text
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* (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
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* - unsigned char *ss: pointer to output shared secret
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* (an already allocated array of KYBER_SSBYTES bytes)
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* - const unsigned char *pk: pointer to input public key
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* (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
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*
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* Returns 0 (success)
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**************************************************/
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int PQCLEAN_KYBER768_CLEAN_crypto_kem_enc(unsigned char ct[KYBER_CIPHERTEXTBYTES],
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unsigned char ss[KYBER_SSBYTES],
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const unsigned char pk[KYBER_PUBLICKEYBYTES]) {
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uint8_t buf[2 * KYBER_SYMBYTES];
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/* Will contain key, coins */
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uint8_t kr[2 * KYBER_SYMBYTES];
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randombytes(buf, KYBER_SYMBYTES);
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/* Don't release system RNG output */
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hash_h(buf, buf, KYBER_SYMBYTES);
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/* Multitarget countermeasure for coins + contributory KEM */
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hash_h(buf + KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
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hash_g(kr, buf, 2 * KYBER_SYMBYTES);
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/* coins are in kr+KYBER_SYMBYTES */
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PQCLEAN_KYBER768_CLEAN_indcpa_enc(ct, buf, pk, kr + KYBER_SYMBYTES);
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/* overwrite coins in kr with H(c) */
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hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES);
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/* hash concatenation of pre-k and H(c) to k */
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kdf(ss, kr, 2 * KYBER_SYMBYTES);
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return 0;
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}
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/*************************************************
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* Name: PQCLEAN_KYBER768_CLEAN_crypto_kem_dec
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*
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* Description: Generates shared secret for given
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* cipher text and private key
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*
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* Arguments: - unsigned char *ss: pointer to output shared secret
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* (an already allocated array of KYBER_SSBYTES bytes)
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* - const unsigned char *ct: pointer to input cipher text
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* (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
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* - const unsigned char *sk: pointer to input private key
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* (an already allocated array of KYBER_SECRETKEYBYTES bytes)
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*
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* Returns 0.
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*
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* On failure, ss will contain a pseudo-random value.
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**************************************************/
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int PQCLEAN_KYBER768_CLEAN_crypto_kem_dec(unsigned char ss[KYBER_SSBYTES],
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const unsigned char ct[KYBER_CIPHERTEXTBYTES],
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const unsigned char sk[KYBER_SECRETKEYBYTES]) {
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size_t i;
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int fail;
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uint8_t buf[2 * KYBER_SYMBYTES];
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/* Will contain key, coins */
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uint8_t kr[2 * KYBER_SYMBYTES];
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uint8_t cmp[KYBER_CIPHERTEXTBYTES];
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const uint8_t *pk = sk + KYBER_INDCPA_SECRETKEYBYTES;
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PQCLEAN_KYBER768_CLEAN_indcpa_dec(buf, ct, sk);
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/* Multitarget countermeasure for coins + contributory KEM */
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for (i = 0; i < KYBER_SYMBYTES; i++) {
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buf[KYBER_SYMBYTES + i] = sk[KYBER_SECRETKEYBYTES - 2 * KYBER_SYMBYTES + i];
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}
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hash_g(kr, buf, 2 * KYBER_SYMBYTES);
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/* coins are in kr+KYBER_SYMBYTES */
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PQCLEAN_KYBER768_CLEAN_indcpa_enc(cmp, buf, pk, kr + KYBER_SYMBYTES);
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fail = PQCLEAN_KYBER768_CLEAN_verify(ct, cmp, KYBER_CIPHERTEXTBYTES);
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/* overwrite coins in kr with H(c) */
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hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES);
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/* Overwrite pre-k with z on re-encryption failure */
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PQCLEAN_KYBER768_CLEAN_cmov(kr, sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES, (uint8_t)fail);
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/* hash concatenation of pre-k and H(c) to k */
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kdf(ss, kr, 2 * KYBER_SYMBYTES);
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return 0;
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}
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