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/* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0"
*
* Written by Nir Drucker and Shay Gueron
* AWS Cryptographic Algorithms Group.
* (ndrucker@amazon.com, gueron@amazon.com)
*/
#include <string.h>
#include "decode.h"
#include "gf2x.h"
#include "parallel_hash.h"
#include "sampling.h"
#include "tls/s2n_kem.h"
_INLINE_ void
split_e(OUT split_e_t *splitted_e, IN const e_t *e)
{
// Copy lower bytes (e0)
memcpy(splitted_e->val[0].raw, e->raw, R_SIZE);
// Now load second value
for(uint32_t i = R_SIZE; i < N_SIZE; ++i)
{
splitted_e->val[1].raw[i - R_SIZE] =
((e->raw[i] << LAST_R_BYTE_TRAIL) | (e->raw[i - 1] >> LAST_R_BYTE_LEAD));
}
// Fix corner case
if(N_SIZE < (2ULL * R_SIZE))
{
splitted_e->val[1].raw[R_SIZE - 1] = (e->raw[N_SIZE - 1] >> LAST_R_BYTE_LEAD);
}
// Fix last value
splitted_e->val[0].raw[R_SIZE - 1] &= LAST_R_BYTE_MASK;
splitted_e->val[1].raw[R_SIZE - 1] &= LAST_R_BYTE_MASK;
}
_INLINE_ void
merge_e(OUT e_t *e, IN const split_e_t *splitted_e)
{
memcpy(e->raw, splitted_e->val[0].raw, R_SIZE);
e->raw[R_SIZE - 1] = ((splitted_e->val[1].raw[0] << LAST_R_BYTE_LEAD) |
(e->raw[R_SIZE - 1] & LAST_R_BYTE_MASK));
// Now load second value
for(uint32_t i = 1; i < R_SIZE; ++i)
{
e->raw[R_SIZE + i - 1] =
((splitted_e->val[1].raw[i] << LAST_R_BYTE_LEAD) |
(splitted_e->val[1].raw[i - 1] >> LAST_R_BYTE_TRAIL));
}
// Mask last byte
if(N_SIZE == (2ULL * R_SIZE))
{
e->raw[N_SIZE - 1] =
(splitted_e->val[1].raw[R_SIZE - 1] >> LAST_R_BYTE_TRAIL);
}
}
_INLINE_ ret_t
encrypt(OUT ct_t *ct,
IN const pk_t *pk,
IN const seed_t *seed,
IN const split_e_t *splitted_e)
{
DEFER_CLEANUP(padded_r_t m = {0}, padded_r_cleanup);
DEFER_CLEANUP(dbl_pad_ct_t p_ct, dbl_pad_ct_cleanup);
// Pad the public key
pad_pk_t p_pk = {0};
p_pk[0].val = pk->val[0];
p_pk[1].val = pk->val[1];
DMSG(" Sampling m.\n");
GUARD(sample_uniform_r_bits(&m.val, seed, NO_RESTRICTION));
DMSG(" Calculating the ciphertext.\n");
GUARD(gf2x_mod_mul((uint64_t *)&p_ct[0], (uint64_t *)&m, (uint64_t *)&p_pk[0]));
GUARD(gf2x_mod_mul((uint64_t *)&p_ct[1], (uint64_t *)&m, (uint64_t *)&p_pk[1]));
DMSG(" Addding Error to the ciphertext.\n");
GUARD(
gf2x_add(p_ct[0].val.raw, p_ct[0].val.raw, splitted_e->val[0].raw, R_SIZE));
GUARD(
gf2x_add(p_ct[1].val.raw, p_ct[1].val.raw, splitted_e->val[1].raw, R_SIZE));
// Copy the data outside
ct->val[0] = p_ct[0].val;
ct->val[1] = p_ct[1].val;
print("m: ", (uint64_t *)m.val.raw, R_BITS);
print("c0: ", (uint64_t *)p_ct[0].val.raw, R_BITS);
print("c1: ", (uint64_t *)p_ct[1].val.raw, R_BITS);
return SUCCESS;
}
_INLINE_ ret_t
calc_pk(OUT pk_t *pk, IN const seed_t *g_seed, IN const pad_sk_t p_sk)
{
// PK is dbl padded because modmul require some scratch space for the
// multiplication result
dbl_pad_pk_t p_pk = {0};
// Intialized padding to zero
DEFER_CLEANUP(padded_r_t g = {0}, padded_r_cleanup);
GUARD(sample_uniform_r_bits(&g.val, g_seed, MUST_BE_ODD));
// Calculate (g0, g1) = (g*h1, g*h0)
GUARD(gf2x_mod_mul((uint64_t *)&p_pk[0], (const uint64_t *)&g,
(const uint64_t *)&p_sk[1]));
GUARD(gf2x_mod_mul((uint64_t *)&p_pk[1], (const uint64_t *)&g,
(const uint64_t *)&p_sk[0]));
// Copy the data to the output parameters.
pk->val[0] = p_pk[0].val;
pk->val[1] = p_pk[1].val;
print("g: ", (uint64_t *)g.val.raw, R_BITS);
print("g0: ", (uint64_t *)&p_pk[0], R_BITS);
print("g1: ", (uint64_t *)&p_pk[1], R_BITS);
return SUCCESS;
}
// Generate the Shared Secret (K(e))
_INLINE_ void
get_ss(OUT ss_t *out, IN const e_t *e)
{
DMSG(" Enter get_ss.\n");
// Calculate the hash
DEFER_CLEANUP(sha_hash_t hash = {0}, sha_hash_cleanup);
parallel_hash(&hash, e->raw, sizeof(*e));
// Truncate the final hash into K by copying only the LSBs
memcpy(out->raw, hash.u.raw, sizeof(*out));
secure_clean(hash.u.raw, sizeof(hash));
DMSG(" Exit get_ss.\n");
}
////////////////////////////////////////////////////////////////
// The three APIs below (keygeneration, encapsulate, decapsulate) are defined by
// NIST: In addition there are two KAT versions of this API as defined.
////////////////////////////////////////////////////////////////
int
BIKE1_L1_R1_crypto_kem_keypair(OUT unsigned char *pk, OUT unsigned char *sk)
{
// Convert to this implementation types
pk_t *l_pk = (pk_t *)pk;
DEFER_CLEANUP(ALIGN(8) sk_t l_sk = {0}, sk_cleanup);
// For DRBG and AES_PRF
DEFER_CLEANUP(seeds_t seeds = {0}, seeds_cleanup);
DEFER_CLEANUP(aes_ctr_prf_state_t h_prf_state = {0}, aes_ctr_prf_state_cleanup);
// Padded for internal use only (the padded data is not released).
DEFER_CLEANUP(pad_sk_t p_sk = {0}, pad_sk_cleanup);
// Get the entropy seeds.
get_seeds(&seeds);
DMSG(" Enter crypto_kem_keypair.\n");
DMSG(" Calculating the secret key.\n");
// h0 and h1 use the same context
GUARD(init_aes_ctr_prf_state(&h_prf_state, MAX_AES_INVOKATION, &seeds.seed[0]));
GUARD(generate_sparse_rep((uint64_t *)&p_sk[0], l_sk.wlist[0].val, DV, R_BITS,
sizeof(p_sk[0]), &h_prf_state));
// Copy data
l_sk.bin[0] = p_sk[0].val;
GUARD(generate_sparse_rep((uint64_t *)&p_sk[1], l_sk.wlist[1].val, DV, R_BITS,
sizeof(p_sk[1]), &h_prf_state));
// Copy data
l_sk.bin[1] = p_sk[1].val;
DMSG(" Calculating the public key.\n");
GUARD(calc_pk(l_pk, &seeds.seed[1], p_sk));
memcpy(sk, &l_sk, sizeof(l_sk));
print("h0: ", (uint64_t *)&l_sk.bin[0], R_BITS);
print("h1: ", (uint64_t *)&l_sk.bin[1], R_BITS);
print("h0c:", (uint64_t *)&l_sk.wlist[0], SIZEOF_BITS(compressed_idx_dv_t));
print("h1c:", (uint64_t *)&l_sk.wlist[1], SIZEOF_BITS(compressed_idx_dv_t));
DMSG(" Exit crypto_kem_keypair.\n");
return SUCCESS;
}
// Encapsulate - pk is the public key,
// ct is a key encapsulation message (ciphertext),
// ss is the shared secret.
int
BIKE1_L1_R1_crypto_kem_enc(OUT unsigned char * ct,
OUT unsigned char * ss,
IN const unsigned char *pk)
{
DMSG(" Enter crypto_kem_enc.\n");
// Convert to this implementation types
const pk_t *l_pk = (const pk_t *)pk;
ct_t * l_ct = (ct_t *)ct;
ss_t * l_ss = (ss_t *)ss;
DEFER_CLEANUP(padded_e_t e = {0}, padded_e_cleanup);
// For NIST DRBG_CTR
DEFER_CLEANUP(seeds_t seeds = {0}, seeds_cleanup);
DEFER_CLEANUP(aes_ctr_prf_state_t e_prf_state = {0}, aes_ctr_prf_state_cleanup);
// Get the entrophy seeds
get_seeds(&seeds);
// Random data generator
// Using first seed
GUARD(init_aes_ctr_prf_state(&e_prf_state, MAX_AES_INVOKATION, &seeds.seed[0]));
DMSG(" Generating error.\n");
ALIGN(8) compressed_idx_t_t dummy;
GUARD(generate_sparse_rep((uint64_t *)&e, dummy.val, T1, N_BITS, sizeof(e),
&e_prf_state));
print("e: ", (uint64_t *)&e.val, sizeof(e) * 8);
// Split e into e0 and e1. Initialization is done in split_e
DEFER_CLEANUP(split_e_t splitted_e, split_e_cleanup);
split_e(&splitted_e, &e.val);
print("e0: ", (uint64_t *)splitted_e.val[0].raw, R_BITS);
print("e1: ", (uint64_t *)splitted_e.val[1].raw, R_BITS);
// Computing ct = enc(pk, e)
// Using second seed
DMSG(" Encrypting.\n");
GUARD(encrypt(l_ct, l_pk, &seeds.seed[1], &splitted_e));
DMSG(" Generating shared secret.\n");
get_ss(l_ss, &e.val);
print("ss: ", (uint64_t *)l_ss->raw, SIZEOF_BITS(*l_ss));
DMSG(" Exit crypto_kem_enc.\n");
return SUCCESS;
}
// Decapsulate - ct is a key encapsulation message (ciphertext),
// sk is the private key,
// ss is the shared secret
int
BIKE1_L1_R1_crypto_kem_dec(OUT unsigned char * ss,
IN const unsigned char *ct,
IN const unsigned char *sk)
{
DMSG(" Enter crypto_kem_dec.\n");
// Convert to this implementation types
const ct_t *l_ct = (const ct_t *)ct;
ss_t * l_ss = (ss_t *)ss;
DEFER_CLEANUP(ALIGN(8) sk_t l_sk, sk_cleanup);
memcpy(&l_sk, sk, sizeof(l_sk));
// Force zero initialization
DEFER_CLEANUP(syndrome_t syndrome = {0}, syndrome_cleanup);
DEFER_CLEANUP(split_e_t e, split_e_cleanup);
DEFER_CLEANUP(e_t merged_e = {0}, e_cleanup);
DMSG(" Computing s.\n");
GUARD(compute_syndrome(&syndrome, l_ct, &l_sk));
DMSG(" Decoding.\n");
GUARD(decode(&e, &syndrome, l_ct, &l_sk));
// Check if the error weight equals T1
if(T1 != r_bits_vector_weight(&e.val[0]) + r_bits_vector_weight(&e.val[1]))
{
MSG(" Error weight is not t\n");
BIKE_ERROR(E_ERROR_WEIGHT_IS_NOT_T);
}
merge_e(&merged_e, &e);
get_ss(l_ss, &merged_e);
DMSG(" Exit crypto_kem_dec.\n");
return SUCCESS;
}
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