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strongswan/src/libstrongswan/plugins/bliss/bliss_private_key.c

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/*
* Copyright (C) 2014-2016 Andreas Steffen
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "bliss_private_key.h"
#include "bliss_public_key.h"
#include "bliss_param_set.h"
#include "bliss_utils.h"
#include "bliss_sampler.h"
#include "bliss_signature.h"
#include "bliss_bitpacker.h"
#include "ntt_fft.h"
#include "ntt_fft_reduce.h"
#include <crypto/mgf1/mgf1_bitspender.h>
#include <asn1/asn1.h>
#include <asn1/asn1_parser.h>
#include <asn1/oid.h>
#define _GNU_SOURCE
#include <stdlib.h>
typedef struct private_bliss_private_key_t private_bliss_private_key_t;
#define SECRET_KEY_TRIALS_MAX 50
/**
* Private data of a bliss_private_key_t object.
*/
struct private_bliss_private_key_t {
/**
* Public interface for this signer.
*/
bliss_private_key_t public;
/**
* BLISS signature parameter set
*/
bliss_param_set_t *set;
/**
* BLISS secret key S1 (coefficients of polynomial f)
*/
int8_t *s1;
/**
* BLISS secret key S2 (coefficients of polynomial 2g + 1)
*/
int8_t *s2;
/**
* NTT of BLISS public key a (coefficients of polynomial (2g + 1)/f)
*/
uint32_t *A;
/**
* NTT of BLISS public key in Montgomery representation Ar = rA mod
*/
uint32_t *Ar;
/**
* reference count
*/
refcount_t ref;
};
METHOD(private_key_t, get_type, key_type_t,
private_bliss_private_key_t *this)
{
return KEY_BLISS;
}
/**
* Multiply secret vector s with binary challenge vector c
*/
static void multiply_by_c(int8_t *s, int n, uint16_t *c_indices,
uint16_t kappa, int32_t *product)
{
int i, j, index;
for (i = 0; i < n; i++)
{
product[i] = 0;
for (j = 0; j < kappa; j++)
{
index = c_indices[j];
if (i - index < 0)
{
product[i] -= s[i - index + n];
}
else
{
product[i] += s[i - index];
}
}
}
}
/**
* BLISS-B GreedySC algorithm
*/
static void greedy_sc(int8_t *s1, int8_t *s2, int n, uint16_t *c_indices,
uint16_t kappa, int32_t *v1, int32_t *v2)
{
int i, j, index;
int32_t sign;
for (i = 0; i < n; i++)
{
v1[i] = v2[i] = 0;
}
for (j = 0; j < kappa; j++)
{
index = c_indices[j];
sign = 0;
for (i = 0; i < index; i++)
{
sign -= (v1[i] * s1[i - index + n] + v2[i] * s2[i - index + n]);
}
for (i = index; i < n; i++)
{
sign += (v1[i] * s1[i - index] + v2[i] * s2[i - index]);
}
for (i = 0; i < index; i++)
{
if (sign > 0)
{
v1[i] += s1[i - index + n];
v2[i] += s2[i - index + n];
}
else
{
v1[i] -= s1[i - index + n];
v2[i] -= s2[i - index + n];
}
}
for (i = index; i < n; i++)
{
if (sign > 0)
{
v1[i] -= s1[i - index];
v2[i] -= s2[i - index];
}
else
{
v1[i] += s1[i - index];
v2[i] += s2[i - index];
}
}
}
}
/**
* Compute a BLISS signature
*/
static bool sign_bliss(private_bliss_private_key_t *this, hash_algorithm_t alg,
chunk_t data, chunk_t *signature)
{
ntt_fft_t *fft;
bliss_signature_t *sig;
bliss_sampler_t *sampler = NULL;
rng_t *rng;
hasher_t *hasher;
hash_algorithm_t mgf1_alg, oracle_alg;
size_t mgf1_seed_len;
uint8_t mgf1_seed_buf[HASH_SIZE_SHA512], data_hash_buf[HASH_SIZE_SHA512];
chunk_t mgf1_seed, data_hash;
uint16_t q, q2, p, p2, *c_indices, tests = 0;
uint32_t *ay;
int32_t *y1, *y2, *z1, *z2, *u, *s1c, *s2c;
int32_t y1_min = 0, y1i, y1_max = 0, y2_min = 0, y2i, y2_max = 0;
int32_t scalar, norm, ui;
int16_t *ud, *uz2d, *z2d, value;
int i, n;
double mean1 = 0, mean2 = 0, sigma1 = 0, sigma2 = 0;
bool accepted, positive, success = FALSE, use_bliss_b;
/* Initialize signature */
*signature = chunk_empty;
/* Create data hash using configurable hash algorithm */
hasher = lib->crypto->create_hasher(lib->crypto, alg);
if (!hasher)
{
return FALSE;
}
data_hash = chunk_create(data_hash_buf, hasher->get_hash_size(hasher));
if (!hasher->get_hash(hasher, data, data_hash_buf))
{
hasher->destroy(hasher);
return FALSE;
}
hasher->destroy(hasher);
/* Set MGF1 hash algorithm and seed length based on security strength */
if (this->set->strength > 160)
{
mgf1_alg = HASH_SHA256;
mgf1_seed_len = HASH_SIZE_SHA256;
}
else
{
mgf1_alg = HASH_SHA1;
mgf1_seed_len = HASH_SIZE_SHA1;
}
mgf1_seed = chunk_create(mgf1_seed_buf, mgf1_seed_len);
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
if (!rng)
{
return FALSE;
}
/* MGF1 hash algorithm to be used for random oracle */
oracle_alg = HASH_SHA512;
/* Initialize a couple of needed variables */
n = this->set->n;
q = this->set->q;
p = this->set->p;
q2 = 2 * q;
p2 = p / 2;
ay = malloc(n * sizeof(uint32_t));
z2 = malloc(n * sizeof(int32_t));
s1c = malloc(n * sizeof(int32_t));
s2c = malloc(n * sizeof(int32_t));
u = malloc(n * sizeof(int32_t));
uz2d = malloc(n * sizeof(int16_t));
sig = bliss_signature_create(this->set);
sig->get_parameters(sig, &z1, &z2d, &c_indices);
y1 = z1;
y2 = z2;
ud = z2d;
fft = ntt_fft_create(this->set->fft_params);
/* Use of the enhanced BLISS-B signature algorithm? */
switch (this->set->id)
{
default:
case BLISS_I:
case BLISS_II:
case BLISS_III:
case BLISS_IV:
use_bliss_b = FALSE;
break;
case BLISS_B_I:
case BLISS_B_II:
case BLISS_B_III:
case BLISS_B_IV:
use_bliss_b = TRUE;
break;
}
while (true)
{
tests++;
if (!rng->get_bytes(rng, mgf1_seed_len, mgf1_seed_buf))
{
goto end;
}
DESTROY_IF(sampler);
sampler = bliss_sampler_create(mgf1_alg, mgf1_seed, this->set);
if (!sampler)
{
goto end;
}
/* Gaussian sampling for vectors y1 and y2 */
for (i = 0; i < n; i++)
{
if (!sampler->gaussian(sampler, &y1i) ||
!sampler->gaussian(sampler, &y2i))
{
goto end;
}
y1[i] = y1i;
y2[i] = y2i;
/* Collect statistical data on rejection sampling */
if (i == 0)
{
y1_min = y1_max = y1i;
y2_min = y2_max = y2i;
}
else
{
if (y1i < y1_min)
{
y1_min = y1i;
}
else if (y1i > y1_max)
{
y1_max = y1i;
}
if (y2i < y2_min)
{
y2_min = y2i;
}
else if (y2i > y2_max)
{
y2_max = y2i;
}
}
mean1 += y1i;
mean2 += y2i;
sigma1 += y1i * y1i;
sigma2 += y2i * y2i;
ay[i] = y1i < 0 ? q + y1i : y1i;
}
/* Compute statistics on vectors y1 and y2 */
mean1 /= n;
mean2 /= n;
sigma1 /= n;
sigma2 /= n;
sigma2 -= mean1 * mean1;
sigma2 -= mean2 * mean2;
DBG2(DBG_LIB, "y1 = %d..%d (sigma2 = %5.0f, mean = %4.1f)",
y1_min, y1_max, sigma1, mean1);
DBG2(DBG_LIB, "y2 = %d..%d (sigma2 = %5.0f, mean = %4.1f)",
y2_min, y2_max, sigma2, mean2);
fft->transform(fft, ay, ay, FALSE);
for (i = 0; i < n; i++)
{
ay[i] = ntt_fft_mreduce(this->Ar[i] * ay[i], this->set->fft_params);
}
fft->transform(fft, ay, ay, TRUE);
for (i = 0; i < n; i++)
{
ui = 2 * this->set->q2_inv * (int32_t)ay[i] + y2[i];
u[i] = ((ui < 0) ? q2 + ui : ui) % q2;
}
bliss_utils_round_and_drop(this->set, u, ud);
/* Detailed debugging information */
DBG3(DBG_LIB, " i u[i] ud[i]");
for (i = 0; i < n; i++)
{
DBG3(DBG_LIB, "%3d %6d %4d", i, u[i], ud[i]);
}
if (!bliss_utils_generate_c(oracle_alg, data_hash, ud, this->set,
c_indices))
{
goto end;
}
if (use_bliss_b)
{
/* Compute v = (s1c, s2c) with the GreedySC algorithm */
greedy_sc(this->s1, this->s2, n, c_indices, this->set->kappa,
s1c, s2c);
/* Compute norm = ||v||^2 = ||Sc'||^2 */
norm = bliss_utils_scalar_product(s1c, s1c, n) +
bliss_utils_scalar_product(s2c, s2c, n);
/* Just in case. ||v||^2 <= P_max should always be fulfilled */
if (norm > this->set->p_max)
{
goto end;
}
}
else
{
/* Compute s*c */
multiply_by_c(this->s1, n, c_indices, this->set->kappa, s1c);
multiply_by_c(this->s2, n, c_indices, this->set->kappa, s2c);
/* Compute norm = |Sc||^2 */
norm = bliss_utils_scalar_product(s1c, s1c, n) +
bliss_utils_scalar_product(s2c, s2c, n);
}
if (!sampler->bernoulli_exp(sampler, this->set->M - norm, &accepted))
{
goto end;
}
if (use_bliss_b)
{
DBG2(DBG_LIB, "norm2(s1*c') + norm2(s2*c') = %u (%u max), %s",
norm, this->set->p_max, accepted ? "accepted" : "rejected");
}
else
{
DBG2(DBG_LIB, "norm2(s1*c) + norm2(s2*c) = %u, %s",
norm, accepted ? "accepted" : "rejected");
}
if (!accepted)
{
continue;
}
/* Compute z */
if (!sampler->sign(sampler, &positive))
{
goto end;
}
for (i = 0; i < n; i++)
{
if (positive)
{
z1[i] = y1[i] + s1c[i];
z2[i] = y2[i] + s2c[i];
}
else
{
z1[i] = y1[i] - s1c[i];
z2[i] = y2[i] - s2c[i];
}
}
/* Reject with probability 1/cosh(scalar/sigma^2) */
scalar = bliss_utils_scalar_product(z1, s1c, n) +
bliss_utils_scalar_product(z2, s2c, n);
if (!sampler->bernoulli_cosh(sampler, scalar, &accepted))
{
goto end;
}
DBG2(DBG_LIB, "scalar(z1,s1*c) + scalar(z2,s2*c) = %d, %s",
scalar, accepted ? "accepted" : "rejected");
if (!accepted)
{
continue;
}
/* Compute z2 with dropped bits */
for (i = 0; i < n; i++)
{
u[i] -= z2[i];
if (u[i] < 0)
{
u[i] += q2;
}
else if (u[i] >= q2)
{
u[i] -= q2;
}
}
bliss_utils_round_and_drop(this->set, u, uz2d);
for (i = 0; i < n; i++)
{
value = ud[i] - uz2d[i];
if (value <= -p2)
{
value += p;
}
else if (value > p2)
{
value -= p;
}
z2d[i] = value;
}
if (!bliss_utils_check_norms(this->set, z1, z2d))
{
continue;
}
*signature = sig->get_encoding(sig);
if (signature->len == 0)
{
DBG1(DBG_LIB, "inefficient Huffman coding of signature");
continue;
}
DBG2(DBG_LIB, "signature generation needed %u round%s", tests,
(tests == 1) ? "" : "s");
break;
}
success = TRUE;
end:
/* cleanup */
DESTROY_IF(sampler);
sig->destroy(sig);
fft->destroy(fft);
rng->destroy(rng);
memwipe(s1c, n * sizeof(int32_t));
memwipe(s2c, n * sizeof(int32_t));
free(s1c);
free(s2c);
free(ay);
free(z2);
free(u);
free(uz2d);
return success;
}
METHOD(private_key_t, sign, bool,
private_bliss_private_key_t *this, signature_scheme_t scheme,
chunk_t data, chunk_t *signature)
{
switch (scheme)
{
case SIGN_BLISS_WITH_SHA2_256:
return sign_bliss(this, HASH_SHA256, data, signature);
case SIGN_BLISS_WITH_SHA2_384:
return sign_bliss(this, HASH_SHA384, data, signature);
case SIGN_BLISS_WITH_SHA2_512:
return sign_bliss(this, HASH_SHA512, data, signature);
case SIGN_BLISS_WITH_SHA3_256:
return sign_bliss(this, HASH_SHA3_256, data, signature);
case SIGN_BLISS_WITH_SHA3_384:
return sign_bliss(this, HASH_SHA3_384, data, signature);
case SIGN_BLISS_WITH_SHA3_512:
return sign_bliss(this, HASH_SHA3_512, data, signature);
default:
DBG1(DBG_LIB, "signature scheme %N not supported with BLISS",
signature_scheme_names, scheme);
return FALSE;
}
}
METHOD(private_key_t, decrypt, bool,
private_bliss_private_key_t *this, encryption_scheme_t scheme,
chunk_t crypto, chunk_t *plain)
{
DBG1(DBG_LIB, "encryption scheme %N not supported",
encryption_scheme_names, scheme);
return FALSE;
}
METHOD(private_key_t, get_keysize, int,
private_bliss_private_key_t *this)
{
return this->set->strength;
}
METHOD(private_key_t, get_public_key, public_key_t*,
private_bliss_private_key_t *this)
{
public_key_t *public;
chunk_t pubkey;
pubkey = bliss_public_key_info_encode(this->set->oid, this->A, this->set);
public = lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_BLISS,
BUILD_BLOB_ASN1_DER, pubkey, BUILD_END);
free(pubkey.ptr);
return public;
}
METHOD(private_key_t, get_encoding, bool,
private_bliss_private_key_t *this, cred_encoding_type_t type,
chunk_t *encoding)
{
switch (type)
{
case PRIVKEY_ASN1_DER:
case PRIVKEY_PEM:
{
chunk_t s1, s2, pubkey;
bliss_bitpacker_t *packer;
size_t s_bits;
int8_t value;
bool success = TRUE;
int i;
pubkey = bliss_public_key_encode(this->A, this->set);
/* Use either 2 or 3 bits per array element */
s_bits = 2 + (this->set->non_zero2 > 0);
/* Encode secret s1 */
packer = bliss_bitpacker_create(s_bits * this->set->n);
for (i = 0; i < this->set->n; i++)
{
packer->write_bits(packer, this->s1[i], s_bits);
}
s1 = packer->extract_buf(packer);
packer->destroy(packer);
/* Encode secret s2 */
packer = bliss_bitpacker_create(s_bits * this->set->n);
for (i = 0; i < this->set->n; i++)
{
value = this->s2[i];
if (i == 0)
{
value -= 1;
}
value /= 2;
packer->write_bits(packer, value, s_bits);
}
s2 = packer->extract_buf(packer);
packer->destroy(packer);
*encoding = asn1_wrap(ASN1_SEQUENCE, "mmss",
asn1_build_known_oid(this->set->oid),
asn1_bitstring("m", pubkey),
asn1_bitstring("m", s1),
asn1_bitstring("m", s2)
);
if (type == PRIVKEY_PEM)
{
chunk_t asn1_encoding = *encoding;
success = lib->encoding->encode(lib->encoding, PRIVKEY_PEM,
NULL, encoding, CRED_PART_BLISS_PRIV_ASN1_DER,
asn1_encoding, CRED_PART_END);
chunk_clear(&asn1_encoding);
}
return success;
}
default:
return FALSE;
}
}
METHOD(private_key_t, get_fingerprint, bool,
private_bliss_private_key_t *this, cred_encoding_type_t type, chunk_t *fp)
{
bool success;
if (lib->encoding->get_cache(lib->encoding, type, this, fp))
{
return TRUE;
}
success = bliss_public_key_fingerprint(this->set->oid, this->A,
this->set, type, fp);
if (success)
{
lib->encoding->cache(lib->encoding, type, this, *fp);
}
return success;
}
METHOD(private_key_t, get_ref, private_key_t*,
private_bliss_private_key_t *this)
{
ref_get(&this->ref);
return &this->public.key;
}
METHOD(private_key_t, destroy, void,
private_bliss_private_key_t *this)
{
if (ref_put(&this->ref))
{
lib->encoding->clear_cache(lib->encoding, this);
if (this->s1)
{
memwipe(this->s1, this->set->n * sizeof(int8_t));
free(this->s1);
}
if (this->s2)
{
memwipe(this->s2, this->set->n * sizeof(int8_t));
free(this->s2);
}
free(this->A);
free(this->Ar);
free(this);
}
}
/**
* Internal generic constructor
*/
static private_bliss_private_key_t *bliss_private_key_create_empty(void)
{
private_bliss_private_key_t *this;
INIT(this,
.public = {
.key = {
.get_type = _get_type,
.sign = _sign,
.decrypt = _decrypt,
.get_keysize = _get_keysize,
.get_public_key = _get_public_key,
.equals = private_key_equals,
.belongs_to = private_key_belongs_to,
.get_fingerprint = _get_fingerprint,
.has_fingerprint = private_key_has_fingerprint,
.get_encoding = _get_encoding,
.get_ref = _get_ref,
.destroy = _destroy,
},
},
.ref = 1,
);
return this;
}
/**
* Compute the scalar product of a vector x with a negative wrapped vector y
*/
static int16_t wrapped_product(int8_t *x, int8_t *y, int n, int shift)
{
int16_t product = 0;
int i;
for (i = 0; i < n - shift; i++)
{
product += x[i] * y[i + shift];
}
for (i = n - shift; i < n; i++)
{
product -= x[i] * y[i + shift - n];
}
return product;
}
/**
* Apply a negative wrapped rotation to a vector x
*/
static void wrap(int16_t *x, int n, int shift, int16_t *x_wrapped)
{
int i;
for (i = 0; i < n - shift; i++)
{
x_wrapped[i + shift] = x[i];
}
for (i = n - shift; i < n; i++)
{
x_wrapped[i + shift - n] = -x[i];
}
}
/**
* int16_t compare function needed for qsort()
*/
static int compare(const int16_t *a, const int16_t *b)
{
int16_t temp = *a - *b;
if (temp > 0)
{
return 1;
}
else if (temp < 0)
{
return -1;
}
else
{
return 0;
}
}
/**
* Compute the Nk(S) norm of S = (s1, s2)
*/
static uint32_t nks_norm(int8_t *s1, int8_t *s2, int n, uint16_t kappa)
{
int16_t t[n], t_wrapped[n], max_kappa[n];
uint32_t nks = 0;
int i, j;
for (i = 0; i < n; i++)
{
t[i] = wrapped_product(s1, s1, n, i) + wrapped_product(s2, s2, n, i);
}
for (i = 0; i < n; i++)
{
wrap(t, n, i, t_wrapped);
qsort(t_wrapped, n, sizeof(int16_t), (__compar_fn_t)compare);
max_kappa[i] = 0;
for (j = 1; j <= kappa; j++)
{
max_kappa[i] += t_wrapped[n - j];
}
}
qsort(max_kappa, n, sizeof(int16_t), (__compar_fn_t)compare);
for (i = 1; i <= kappa; i++)
{
nks += max_kappa[n - i];
}
return nks;
}
/**
* Compute the inverse x1 of x modulo q as x^(-1) = x^(q-2) mod q
*/
static uint32_t invert(private_bliss_private_key_t *this, uint32_t x)
{
uint32_t x1, x2;
uint16_t q2;
int i, i_max;
q2 = this->set->q - 2;
x1 = (q2 & 1) ? x : 1;
x2 = x;
i_max = 15;
while ((q2 & (1 << i_max)) == 0)
{
i_max--;
}
for (i = 1; i <= i_max; i++)
{
x2 = ntt_fft_mreduce(x2 * x2, this->set->fft_params);
if (q2 & (1 << i))
{
x1 = ntt_fft_mreduce(x1 * x2, this->set->fft_params);
}
}
return x1;
}
/**
* Create a vector with sparse and small coefficients from seed
*/
static int8_t* create_vector_from_seed(private_bliss_private_key_t *this,
hash_algorithm_t alg, chunk_t seed)
{
mgf1_bitspender_t *bitspender;
uint32_t index, sign;
int8_t *vector;
int non_zero;
bitspender = mgf1_bitspender_create(alg, seed, FALSE);
if (!bitspender)
{
return NULL;
}
vector = malloc(sizeof(int8_t) * this->set->n);
memset(vector, 0x00, this->set->n);
non_zero = this->set->non_zero1;
while (non_zero)
{
if (!bitspender->get_bits(bitspender, this->set->n_bits, &index))
{
free(vector);
return NULL;
}
if (vector[index] != 0)
{
continue;
}
if (!bitspender->get_bits(bitspender, 1, &sign))
{
free(vector);
return NULL;
}
vector[index] = sign ? 1 : -1;
non_zero--;
}
non_zero = this->set->non_zero2;
while (non_zero)
{
if (!bitspender->get_bits(bitspender, this->set->n_bits, &index))
{
free(vector);
return NULL;
}
if (vector[index] != 0)
{
continue;
}
if (!bitspender->get_bits(bitspender, 1, &sign))
{
free(vector);
return NULL;
}
vector[index] = sign ? 2 : -2;
non_zero--;
}
bitspender->destroy(bitspender);
return vector;
}
/**
* Generate the secret key S = (s1, s2) fulfilling the Nk(S) norm
*/
static bool create_secret(private_bliss_private_key_t *this, rng_t *rng,
int8_t **s1, int8_t **s2, int *trials)
{
uint8_t seed_buf[32];
uint8_t *f, *g;
uint32_t l2_norm, nks;
int i, n;
chunk_t seed;
size_t seed_len;
hash_algorithm_t alg;
n = this->set->n;
*s1 = NULL;
*s2 = NULL;
/* Set MGF1 hash algorithm and seed length based on security strength */
if (this->set->strength > 160)
{
alg = HASH_SHA256;
seed_len = HASH_SIZE_SHA256;
}
else
{
alg = HASH_SHA1;
seed_len = HASH_SIZE_SHA1;
}
seed = chunk_create(seed_buf, seed_len);
while (*trials < SECRET_KEY_TRIALS_MAX)
{
(*trials)++;
if (!rng->get_bytes(rng, seed_len, seed_buf))
{
return FALSE;
}
f = create_vector_from_seed(this, alg, seed);
if (f == NULL)
{
return FALSE;
}
if (!rng->get_bytes(rng, seed_len, seed_buf))
{
free(f);
return FALSE;
}
g = create_vector_from_seed(this, alg, seed);
if (g == NULL)
{
free(f);
return FALSE;
}
/* Compute 2g + 1 */
for (i = 0; i < n; i++)
{
g[i] *= 2;
}
g[0] += 1;
l2_norm = wrapped_product(f, f, n, 0) + wrapped_product(g, g, n, 0);
nks = nks_norm(f, g, n, this->set->kappa);
switch (this->set->id)
{
case BLISS_I:
case BLISS_II:
case BLISS_III:
case BLISS_IV:
DBG2(DBG_LIB, "l2 norm of s1||s2: %d, Nk(S): %u (%u max)",
l2_norm, nks, this->set->nks_max);
if (nks < this->set->nks_max)
{
*s1 = f;
*s2 = g;
return TRUE;
}
free(f);
free(g);
break;
case BLISS_B_I:
case BLISS_B_II:
case BLISS_B_III:
case BLISS_B_IV:
DBG2(DBG_LIB, "l2 norm of s1||s2: %d, Nk(S): %u",
l2_norm, nks);
*s1 = f;
*s2 = g;
return TRUE;
}
}
return FALSE;
}
/**
* See header.
*/
bliss_private_key_t *bliss_private_key_gen(key_type_t type, va_list args)
{
private_bliss_private_key_t *this;
u_int key_size = BLISS_B_I;
int i, n, trials = 0;
uint32_t *S1, *S2, *a;
uint16_t q;
bool success = FALSE;
bliss_param_set_t *set;
ntt_fft_t *fft;
rng_t *rng;
while (TRUE)
{
switch (va_arg(args, builder_part_t))
{
case BUILD_KEY_SIZE:
key_size = va_arg(args, u_int);
continue;
case BUILD_END:
break;
default:
return NULL;
}
break;
}
if (lib->settings->get_bool(lib->settings, "%s.plugins.bliss.use_bliss_b",
TRUE, lib->ns))
{
switch (key_size)
{
case BLISS_I:
key_size = BLISS_B_I;
break;
case BLISS_II:
key_size = BLISS_B_II;
break;
case BLISS_III:
key_size = BLISS_B_III;
break;
case BLISS_IV:
key_size = BLISS_B_IV;
break;
default:
break;
}
}
/* Only BLISS or BLISS-B types I, III, or IV are currently supported */
set = bliss_param_set_get_by_id(key_size);
if (!set)
{
DBG1(DBG_LIB, "BLISS parameter set %u not supported", key_size);
return NULL;
}
/* Some shortcuts for often used variables */
n = set->n;
q = set->q;
if (set->fft_params->n != n || set->fft_params->q != q)
{
DBG1(DBG_LIB, "FFT parameters do not match BLISS parameters");
return NULL;
}
this = bliss_private_key_create_empty();
this->set = set;
/* We derive the public key from the private key using the FFT */
fft = ntt_fft_create(set->fft_params);
/* Some vectors needed to derive the publi key */
S1 = malloc(n * sizeof(uint32_t));
S2 = malloc(n * sizeof(uint32_t));
a = malloc(n * sizeof(uint32_t));
this->A = malloc(n * sizeof(uint32_t));
this->Ar = malloc(n * sizeof(uint32_t));
/* Instantiate a true random generator */
rng = lib->crypto->create_rng(lib->crypto, RNG_TRUE);
/* Loop until we have an invertible polynomial s1 */
do
{
if (!create_secret(this, rng, &this->s1, &this->s2, &trials))
{
break;
}
/* Convert signed arrays to unsigned arrays before FFT */
for (i = 0; i < n; i++)
{
S1[i] = (this->s1[i] < 0) ? this->s1[i] + q : this->s1[i];
S2[i] = (this->s2[i] > 0) ? q - this->s2[i] : -this->s2[i];
}
fft->transform(fft, S1, S1, FALSE);
fft->transform(fft, S2, S2, FALSE);
success = TRUE;
for (i = 0; i < n; i++)
{
if (S1[i] == 0)
{
DBG1(DBG_LIB, "S1[%d] is zero - s1 is not invertible", i);
free(this->s1);
free(this->s2);
this->s1 = NULL;
this->s2 = NULL;
success = FALSE;
break;
}
this->Ar[i] = invert(this, S1[i]);
this->Ar[i] = ntt_fft_mreduce(S2[i] * this->Ar[i], set->fft_params);
this->A[i] = ntt_fft_mreduce(this->Ar[i], set->fft_params);
}
}
while (!success && trials < SECRET_KEY_TRIALS_MAX);
DBG1(DBG_LIB, "secret key generation %s after %d trial%s",
success ? "succeeded" : "failed", trials, (trials == 1) ? "" : "s");
if (success)
{
fft->transform(fft, this->Ar, a, TRUE);
DBG4(DBG_LIB, " i f g a F G A");
for (i = 0; i < n; i++)
{
DBG4(DBG_LIB, "%4d %3d %3d %5u %5u %5u %5u",
i, this->s1[i], this->s2[i],
ntt_fft_mreduce(a[i], set->fft_params),
S1[i], S2[i], this->A[i]);
}
}
else
{
destroy(this);
}
/* Cleanup */
fft->destroy(fft);
rng->destroy(rng);
memwipe(S1, n * sizeof(uint32_t));
memwipe(S2, n * sizeof(uint32_t));
free(S1);
free(S2);
free(a);
return success ? &this->public : NULL;
}
/**
* ASN.1 definition of a BLISS private key
*/
static const asn1Object_t privkeyObjects[] = {
{ 0, "BLISSPrivateKey", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "keyType", ASN1_OID, ASN1_BODY }, /* 1 */
{ 1, "public", ASN1_BIT_STRING, ASN1_BODY }, /* 2 */
{ 1, "secret1", ASN1_BIT_STRING, ASN1_BODY }, /* 3 */
{ 1, "secret2", ASN1_BIT_STRING, ASN1_BODY }, /* 4 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PRIV_KEY_TYPE 1
#define PRIV_KEY_PUBLIC 2
#define PRIV_KEY_SECRET1 3
#define PRIV_KEY_SECRET2 4
/**
* See header.
*/
bliss_private_key_t *bliss_private_key_load(key_type_t type, va_list args)
{
private_bliss_private_key_t *this;
chunk_t key = chunk_empty, object;
bliss_bitpacker_t *packer;
asn1_parser_t *parser;
size_t s_bits = 0;
int8_t s, s_min = 0, s_max = 0;
uint32_t s_sign = 0x02, s_mask = 0xfffffffc, value, r2;
bool success = FALSE;
int objectID, oid, i;
while (TRUE)
{
switch (va_arg(args, builder_part_t))
{
case BUILD_BLOB_ASN1_DER:
key = va_arg(args, chunk_t);
continue;
case BUILD_END:
break;
default:
return NULL;
}
break;
}
if (key.len == 0)
{
return NULL;
}
this = bliss_private_key_create_empty();
parser = asn1_parser_create(privkeyObjects, key);
parser->set_flags(parser, FALSE, TRUE);
while (parser->iterate(parser, &objectID, &object))
{
switch (objectID)
{
case PRIV_KEY_TYPE:
oid = asn1_known_oid(object);
if (oid == OID_UNKNOWN)
{
goto end;
}
this->set = bliss_param_set_get_by_oid(oid);
if (this->set == NULL)
{
goto end;
}
if (lib->settings->get_bool(lib->settings,
"%s.plugins.bliss.use_bliss_b",TRUE, lib->ns))
{
switch (this->set->id)
{
case BLISS_I:
this->set = bliss_param_set_get_by_id(BLISS_B_I);
break;
case BLISS_III:
this->set = bliss_param_set_get_by_id(BLISS_B_III);
break;
case BLISS_IV:
this->set = bliss_param_set_get_by_id(BLISS_B_IV);
break;
default:
break;
}
}
if (this->set->non_zero2)
{
s_min = -2;
s_max = 2;
s_bits = 3;
}
else
{
s_min = -1;
s_max = 1;
s_bits = 2;
}
s_sign = 1 << (s_bits - 1);
s_mask = ((1 << (32 - s_bits)) - 1) << s_bits;
break;
case PRIV_KEY_PUBLIC:
if (!bliss_public_key_from_asn1(object, this->set, &this->A))
{
goto end;
}
this->Ar = malloc(this->set->n * sizeof(uint32_t));
r2 = this->set->fft_params->r2;
for (i = 0; i < this->set->n; i++)
{
this->Ar[i] = ntt_fft_mreduce(this->A[i] * r2,
this->set->fft_params);
}
break;
case PRIV_KEY_SECRET1:
if (object.len != 1 + (s_bits * this->set->n + 7)/8)
{
goto end;
}
this->s1 = malloc(this->set->n);
/* Skip unused bits octet */
object = chunk_skip(object, 1);
packer = bliss_bitpacker_create_from_data(object);
for (i = 0; i < this->set->n; i++)
{
packer->read_bits(packer, &value, s_bits);
s = (value & s_sign) ? value | s_mask : value;
if (s < s_min || s > s_max)
{
packer->destroy(packer);
goto end;
}
this->s1[i] = s;
}
packer->destroy(packer);
break;
case PRIV_KEY_SECRET2:
if (object.len != 1 + (s_bits * this->set->n + 7)/8)
{
goto end;
}
this->s2 = malloc(this->set->n);
/* Skip unused bits octet */
object = chunk_skip(object, 1);
packer = bliss_bitpacker_create_from_data(object);
for (i = 0; i < this->set->n; i++)
{
packer->read_bits(packer, &value, s_bits);
s = (value & s_sign) ? value | s_mask : value;
if (s < s_min || s > s_max)
{
packer->destroy(packer);
goto end;
}
this->s2[i] = 2 * s;
if (i == 0)
{
this->s2[0] += 1;
}
}
packer->destroy(packer);
break;
}
}
success = parser->success(parser);
end:
parser->destroy(parser);
if (!success)
{
destroy(this);
return NULL;
}
return &this->public;
}
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