mirror of
https://github.com/openssl/openssl.git
synced 2024-12-21 06:09:35 +08:00
335 lines
8.0 KiB
C
335 lines
8.0 KiB
C
/*
|
|
* Copyright 1998-2024 The OpenSSL Project Authors. All Rights Reserved.
|
|
*
|
|
* Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
* this file except in compliance with the License. You can obtain a copy
|
|
* in the file LICENSE in the source distribution or at
|
|
* https://www.openssl.org/source/license.html
|
|
*/
|
|
|
|
#include "internal/cryptlib.h"
|
|
#include "internal/nelem.h"
|
|
#include "bn_local.h"
|
|
|
|
int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
|
|
{
|
|
/*
|
|
* like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d|
|
|
* always holds)
|
|
*/
|
|
|
|
if (r == d) {
|
|
ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
|
|
return 0;
|
|
}
|
|
|
|
if (!(BN_mod(r, m, d, ctx)))
|
|
return 0;
|
|
if (!r->neg)
|
|
return 1;
|
|
/* now -|d| < r < 0, so we have to set r := r + |d| */
|
|
return (d->neg ? BN_sub : BN_add) (r, r, d);
|
|
}
|
|
|
|
int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
|
|
BN_CTX *ctx)
|
|
{
|
|
if (!BN_add(r, a, b))
|
|
return 0;
|
|
return BN_nnmod(r, r, m, ctx);
|
|
}
|
|
|
|
/*
|
|
* BN_mod_add variant that may be used if both a and b are non-negative and
|
|
* less than m. The original algorithm was
|
|
*
|
|
* if (!BN_uadd(r, a, b))
|
|
* return 0;
|
|
* if (BN_ucmp(r, m) >= 0)
|
|
* return BN_usub(r, r, m);
|
|
*
|
|
* which is replaced with addition, subtracting modulus, and conditional
|
|
* move depending on whether or not subtraction borrowed.
|
|
*/
|
|
int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
|
|
const BIGNUM *m)
|
|
{
|
|
size_t i, ai, bi, mtop = m->top;
|
|
BN_ULONG storage[1024 / BN_BITS2];
|
|
BN_ULONG carry, temp, mask, *rp, *tp = storage;
|
|
const BN_ULONG *ap, *bp;
|
|
|
|
if (bn_wexpand(r, mtop) == NULL)
|
|
return 0;
|
|
|
|
if (mtop > OSSL_NELEM(storage)) {
|
|
tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG));
|
|
if (tp == NULL)
|
|
return 0;
|
|
}
|
|
|
|
ap = a->d != NULL ? a->d : tp;
|
|
bp = b->d != NULL ? b->d : tp;
|
|
|
|
for (i = 0, ai = 0, bi = 0, carry = 0; i < mtop;) {
|
|
mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1));
|
|
temp = ((ap[ai] & mask) + carry) & BN_MASK2;
|
|
carry = (temp < carry);
|
|
|
|
mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1));
|
|
tp[i] = ((bp[bi] & mask) + temp) & BN_MASK2;
|
|
carry += (tp[i] < temp);
|
|
|
|
i++;
|
|
ai += (i - a->dmax) >> (8 * sizeof(i) - 1);
|
|
bi += (i - b->dmax) >> (8 * sizeof(i) - 1);
|
|
}
|
|
rp = r->d;
|
|
carry -= bn_sub_words(rp, tp, m->d, mtop);
|
|
for (i = 0; i < mtop; i++) {
|
|
rp[i] = (carry & tp[i]) | (~carry & rp[i]);
|
|
((volatile BN_ULONG *)tp)[i] = 0;
|
|
}
|
|
r->top = mtop;
|
|
r->flags |= BN_FLG_FIXED_TOP;
|
|
r->neg = 0;
|
|
|
|
if (tp != storage)
|
|
OPENSSL_free(tp);
|
|
|
|
return 1;
|
|
}
|
|
|
|
int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
|
|
const BIGNUM *m)
|
|
{
|
|
int ret = bn_mod_add_fixed_top(r, a, b, m);
|
|
|
|
if (ret)
|
|
bn_correct_top(r);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
|
|
BN_CTX *ctx)
|
|
{
|
|
if (!BN_sub(r, a, b))
|
|
return 0;
|
|
return BN_nnmod(r, r, m, ctx);
|
|
}
|
|
|
|
/*
|
|
* BN_mod_sub variant that may be used if both a and b are non-negative,
|
|
* a is less than m, while b is of same bit width as m. It's implemented
|
|
* as subtraction followed by two conditional additions.
|
|
*
|
|
* 0 <= a < m
|
|
* 0 <= b < 2^w < 2*m
|
|
*
|
|
* after subtraction
|
|
*
|
|
* -2*m < r = a - b < m
|
|
*
|
|
* Thus it takes up to two conditional additions to make |r| positive.
|
|
*/
|
|
int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
|
|
const BIGNUM *m)
|
|
{
|
|
size_t i, ai, bi, mtop = m->top;
|
|
BN_ULONG borrow, carry, ta, tb, mask, *rp;
|
|
const BN_ULONG *ap, *bp;
|
|
|
|
if (bn_wexpand(r, mtop) == NULL)
|
|
return 0;
|
|
|
|
rp = r->d;
|
|
ap = a->d != NULL ? a->d : rp;
|
|
bp = b->d != NULL ? b->d : rp;
|
|
|
|
for (i = 0, ai = 0, bi = 0, borrow = 0; i < mtop;) {
|
|
mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1));
|
|
ta = ap[ai] & mask;
|
|
|
|
mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1));
|
|
tb = bp[bi] & mask;
|
|
rp[i] = ta - tb - borrow;
|
|
if (ta != tb)
|
|
borrow = (ta < tb);
|
|
|
|
i++;
|
|
ai += (i - a->dmax) >> (8 * sizeof(i) - 1);
|
|
bi += (i - b->dmax) >> (8 * sizeof(i) - 1);
|
|
}
|
|
ap = m->d;
|
|
for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) {
|
|
ta = ((ap[i] & mask) + carry) & BN_MASK2;
|
|
carry = (ta < carry);
|
|
rp[i] = (rp[i] + ta) & BN_MASK2;
|
|
carry += (rp[i] < ta);
|
|
}
|
|
borrow -= carry;
|
|
for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) {
|
|
ta = ((ap[i] & mask) + carry) & BN_MASK2;
|
|
carry = (ta < carry);
|
|
rp[i] = (rp[i] + ta) & BN_MASK2;
|
|
carry += (rp[i] < ta);
|
|
}
|
|
|
|
r->top = mtop;
|
|
r->flags |= BN_FLG_FIXED_TOP;
|
|
r->neg = 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* BN_mod_sub variant that may be used if both a and b are non-negative and
|
|
* less than m
|
|
*/
|
|
int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
|
|
const BIGNUM *m)
|
|
{
|
|
if (r == m) {
|
|
ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
|
|
return 0;
|
|
}
|
|
|
|
if (!BN_sub(r, a, b))
|
|
return 0;
|
|
if (r->neg)
|
|
return BN_add(r, r, m);
|
|
return 1;
|
|
}
|
|
|
|
/* slow but works */
|
|
int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
|
|
BN_CTX *ctx)
|
|
{
|
|
BIGNUM *t;
|
|
int ret = 0;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
bn_check_top(m);
|
|
|
|
BN_CTX_start(ctx);
|
|
if ((t = BN_CTX_get(ctx)) == NULL)
|
|
goto err;
|
|
if (a == b) {
|
|
if (!BN_sqr(t, a, ctx))
|
|
goto err;
|
|
} else {
|
|
if (!BN_mul(t, a, b, ctx))
|
|
goto err;
|
|
}
|
|
if (!BN_nnmod(r, t, m, ctx))
|
|
goto err;
|
|
bn_check_top(r);
|
|
ret = 1;
|
|
err:
|
|
BN_CTX_end(ctx);
|
|
return ret;
|
|
}
|
|
|
|
int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
|
|
{
|
|
if (!BN_sqr(r, a, ctx))
|
|
return 0;
|
|
/* r->neg == 0, thus we don't need BN_nnmod */
|
|
return BN_mod(r, r, m, ctx);
|
|
}
|
|
|
|
int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
|
|
{
|
|
if (!BN_lshift1(r, a))
|
|
return 0;
|
|
bn_check_top(r);
|
|
return BN_nnmod(r, r, m, ctx);
|
|
}
|
|
|
|
/*
|
|
* BN_mod_lshift1 variant that may be used if a is non-negative and less than
|
|
* m
|
|
*/
|
|
int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m)
|
|
{
|
|
if (!BN_lshift1(r, a))
|
|
return 0;
|
|
bn_check_top(r);
|
|
if (BN_cmp(r, m) >= 0)
|
|
return BN_sub(r, r, m);
|
|
return 1;
|
|
}
|
|
|
|
int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m,
|
|
BN_CTX *ctx)
|
|
{
|
|
BIGNUM *abs_m = NULL;
|
|
int ret;
|
|
|
|
if (!BN_nnmod(r, a, m, ctx))
|
|
return 0;
|
|
|
|
if (m->neg) {
|
|
abs_m = BN_dup(m);
|
|
if (abs_m == NULL)
|
|
return 0;
|
|
abs_m->neg = 0;
|
|
}
|
|
|
|
ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
|
|
bn_check_top(r);
|
|
|
|
BN_free(abs_m);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* BN_mod_lshift variant that may be used if a is non-negative and less than
|
|
* m
|
|
*/
|
|
int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
|
|
{
|
|
if (r != a) {
|
|
if (BN_copy(r, a) == NULL)
|
|
return 0;
|
|
}
|
|
|
|
while (n > 0) {
|
|
int max_shift;
|
|
|
|
/* 0 < r < m */
|
|
max_shift = BN_num_bits(m) - BN_num_bits(r);
|
|
/* max_shift >= 0 */
|
|
|
|
if (max_shift < 0) {
|
|
ERR_raise(ERR_LIB_BN, BN_R_INPUT_NOT_REDUCED);
|
|
return 0;
|
|
}
|
|
|
|
if (max_shift > n)
|
|
max_shift = n;
|
|
|
|
if (max_shift) {
|
|
if (!BN_lshift(r, r, max_shift))
|
|
return 0;
|
|
n -= max_shift;
|
|
} else {
|
|
if (!BN_lshift1(r, r))
|
|
return 0;
|
|
--n;
|
|
}
|
|
|
|
/* BN_num_bits(r) <= BN_num_bits(m) */
|
|
|
|
if (BN_cmp(r, m) >= 0) {
|
|
if (!BN_sub(r, r, m))
|
|
return 0;
|
|
}
|
|
}
|
|
bn_check_top(r);
|
|
|
|
return 1;
|
|
}
|