-rw-r--r-- 3635 libmceliece-20240726/crypto_kem/460896/avx/sk_gen.c raw
/*
This file is for secret-key generation
*/
// 20221230 djb: add linker lines
// linker define genpoly_gen
// linker use gf_mul gf_inv
// linker use vec128_mul_GF
// linker use vec128_mul_asm
// linker use transpose_64x64_asm
#include "sk_gen.h"
#include "randombytes.h"
#include "controlbits.h"
#include "transpose.h"
#include "params.h"
#include "vec128.h"
#include "util.h"
#include "gf.h"
#include "crypto_declassify.h"
#include "crypto_uint16.h"
static inline crypto_uint16 gf_is_zero_declassify(gf t)
{
crypto_uint16 mask = crypto_uint16_zero_mask(t);
crypto_declassify(&mask,sizeof mask);
return mask;
}
/* input: v, a list of GF(2^m) elements in bitsliced form */
/* input: idx, an index */
/* return: the idx-th element in v */
static inline gf extract_gf(uint64_t v[GFBITS][2], int idx)
{
int i;
gf ret;
ret = 0;
for (i = GFBITS-1; i >= 0; i--)
{
ret <<= 1;
ret |= (v[i][idx/64] >> (idx&63)) & 1;
}
return ret;
}
/* same as extract_gf but reduces return value to 1 bit */
static inline uint64_t extract_bit(uint64_t v[GFBITS][2], int idx)
{
int i;
uint64_t ret;
ret = 0;
for (i = GFBITS-1; i >= 0; i--)
ret |= v[i][idx/64];
return (ret >> (idx&63)) & 1;
}
static void transpose_128x128(uint64_t (*in)[2])
{
int i, j, k;
uint64_t m[2][2][64], t;
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
for (k = 0; k < 64; k++)
m[i][j][k] = in[64*i + k][j];
for (k = 0; k < 64; k++)
{
t = m[0][1][k];
m[0][1][k] = m[1][0][k];
m[1][0][k] = t;
}
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
transpose_64x64(m[i][j]);
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
for (k = 0; k < 64; k++)
in[64*i + k][j] = m[i][j][k];
}
/* input: f, element in GF((2^m)^t) */
/* output: out, minimal polynomial of f */
/* return: 0 for success and -1 for failure */
int genpoly_gen(gf *out, gf *f)
{
int i, j, k;
gf t, inv;
uint64_t m;
vec128 mask;
union
{
uint64_t d[ GFBITS ][ 128 ][2];
vec128 v[ GFBITS ][ 128 ];
} buf;
union
{
uint64_t d[GFBITS][2];
vec128 v[GFBITS];
} v;
union
{
uint64_t d[SYS_T][GFBITS][2];
vec128 v[SYS_T][GFBITS];
} mat;
// fill matrix
buf.v[0][0] = vec128_set2x(1, 0);
for (i = 1; i < GFBITS; i++)
buf.v[i][0] = vec128_setzero();
for (j = 0; j < GFBITS; j++)
{
v.v[j] = vec128_setzero();
for (i = SYS_T-1; i >= 0; i--)
{
v.d[j][1] <<= 1;
v.d[j][1] |= v.d[j][0] >> 63;
v.d[j][0] <<= 1;
v.d[j][0] |= (f[i] >> j) & 1;
}
}
for (i = 0; i < GFBITS; i++)
buf.v[i][1] = v.v[i];
for (k = 2; k <= SYS_T; k++)
{
vec128_mul_GF(v.v, v.v, f);
if (k < SYS_T)
{
for (i = 0; i < GFBITS; i++)
buf.v[i][k] = v.v[i];
}
else
{
for (i = 0; i < SYS_T; i++)
out[i] = extract_gf(v.d, i);
}
}
for (i = 0; i < GFBITS; i++)
transpose_128x128(buf.d[i]);
for (j = 0; j < SYS_T; j++)
for (i = 0; i < GFBITS; i++)
mat.v[j][i] = buf.v[i][j];
// gaussian
for (i = 0; i < SYS_T; i++)
{
for (j = i+1; j < SYS_T; j++)
{
m = extract_bit(mat.d[i], i);
m -= 1;
mask = vec128_set2x(m, m);
for (k = 0; k < GFBITS; k++)
mat.v[i][k] ^= mat.v[j][k] & mask;
out[i] ^= out[j] & m;
}
//
t = extract_gf(mat.d[i], i);
if (gf_is_zero_declassify(t)) return -1; // return if not systematic
//
inv = gf_inv(t);
vec128_mul_gf(mat.v[i], mat.v[i], inv);
out[i] = gf_mul(out[i], inv);
for (j = 0; j < SYS_T; j++)
{
if (j != i)
{
t = extract_gf(mat.d[j], i);
vec128_mul_gf(v.v, mat.v[i], t);
vec128_add(mat.v[j], mat.v[j], v.v);
out[j] ^= gf_mul(out[i], t);
}
}
}
return 0;
}