1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
#include "indcpa.h"
#include "params.h"
#include "symmetric.h"
#include "verify.h"
#include "../s2n_pq_random.h"
#include "utils/s2n_safety.h"
#include "tls/s2n_kem.h"
#include <stdlib.h>
/*************************************************
* Name: crypto_kem_keypair
*
* Description: Generates public and private key
* for CCA-secure Kyber key encapsulation mechanism
*
* Arguments: - uint8_t *pk: pointer to output public key (an already allocated array of CRYPTO_PUBLICKEYBYTES bytes)
* - uint8_t *sk: pointer to output private key (an already allocated array of CRYPTO_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int kyber_512_r2_crypto_kem_keypair(uint8_t *pk, uint8_t *sk) {
size_t i;
PQCLEAN_KYBER512_CLEAN_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);
GUARD_AS_POSIX(s2n_get_random_bytes(sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES)); /* Value z for pseudo-random output on reject */
return 0;
}
/*************************************************
* Name: crypto_kem_enc
*
* Description: Generates cipher text and shared
* secret for given public key
*
* Arguments: - uint8_t *ct: pointer to output cipher text (an already allocated array of CRYPTO_CIPHERTEXTBYTES bytes)
* - uint8_t *ss: pointer to output shared secret (an already allocated array of CRYPTO_BYTES bytes)
* - const uint8_t *pk: pointer to input public key (an already allocated array of CRYPTO_PUBLICKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int kyber_512_r2_crypto_kem_enc(uint8_t *ct, uint8_t *ss, const uint8_t *pk) {
uint8_t kr[2 * KYBER_SYMBYTES]; /* Will contain key, coins */
uint8_t buf[2 * KYBER_SYMBYTES];
GUARD_AS_POSIX(s2n_get_random_bytes(buf, KYBER_SYMBYTES));
hash_h(buf, buf, KYBER_SYMBYTES); /* Don't release system RNG output */
hash_h(buf + KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES); /* Multitarget countermeasure for coins + contributory KEM */
hash_g(kr, buf, 2 * KYBER_SYMBYTES);
PQCLEAN_KYBER512_CLEAN_indcpa_enc(ct, buf, pk, kr + KYBER_SYMBYTES); /* coins are in kr+KYBER_SYMBYTES */
hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES); /* overwrite coins in kr with H(c) */
kdf(ss, kr, 2 * KYBER_SYMBYTES); /* hash concatenation of pre-k and H(c) to k */
return 0;
}
/*************************************************
* Name: crypto_kem_dec
*
* Description: Generates shared secret for given
* cipher text and private key
*
* Arguments: - uint8_t *ss: pointer to output shared secret (an already allocated array of CRYPTO_BYTES bytes)
* - const uint8_t *ct: pointer to input cipher text (an already allocated array of CRYPTO_CIPHERTEXTBYTES bytes)
* - const uint8_t *sk: pointer to input private key (an already allocated array of CRYPTO_SECRETKEYBYTES bytes)
*
* Returns 0.
*
* On failure, ss will contain a pseudo-random value.
**************************************************/
int kyber_512_r2_crypto_kem_dec(uint8_t *ss, const uint8_t *ct, const uint8_t *sk) {
size_t i;
uint8_t fail;
uint8_t cmp[KYBER_CIPHERTEXTBYTES];
uint8_t buf[2 * KYBER_SYMBYTES];
uint8_t kr[2 * KYBER_SYMBYTES]; /* Will contain key, coins */
const uint8_t *pk = sk + KYBER_INDCPA_SECRETKEYBYTES;
PQCLEAN_KYBER512_CLEAN_indcpa_dec(buf, ct, sk);
for (i = 0; i < KYBER_SYMBYTES; i++) { /* Multitarget countermeasure for coins + contributory KEM */
buf[KYBER_SYMBYTES + i] = sk[KYBER_SECRETKEYBYTES - 2 * KYBER_SYMBYTES + i]; /* Save hash by storing H(pk) in sk */
}
hash_g(kr, buf, 2 * KYBER_SYMBYTES);
PQCLEAN_KYBER512_CLEAN_indcpa_enc(cmp, buf, pk, kr + KYBER_SYMBYTES); /* coins are in kr+KYBER_SYMBYTES */
fail = PQCLEAN_KYBER512_CLEAN_verify(ct, cmp, KYBER_CIPHERTEXTBYTES);
hash_h(kr + KYBER_SYMBYTES, ct, KYBER_CIPHERTEXTBYTES); /* overwrite coins in kr with H(c) */
PQCLEAN_KYBER512_CLEAN_cmov(kr, sk + KYBER_SECRETKEYBYTES - KYBER_SYMBYTES, KYBER_SYMBYTES, fail); /* Overwrite pre-k with z on re-encryption failure */
kdf(ss, kr, 2 * KYBER_SYMBYTES); /* hash concatenation of pre-k and H(c) to k */
return 0;
}
|
