| /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
| * All rights reserved. |
| * |
| * This package is an SSL implementation written |
| * by Eric Young (eay@cryptsoft.com). |
| * The implementation was written so as to conform with Netscapes SSL. |
| * |
| * This library is free for commercial and non-commercial use as long as |
| * the following conditions are aheared to. The following conditions |
| * apply to all code found in this distribution, be it the RC4, RSA, |
| * lhash, DES, etc., code; not just the SSL code. The SSL documentation |
| * included with this distribution is covered by the same copyright terms |
| * except that the holder is Tim Hudson (tjh@cryptsoft.com). |
| * |
| * Copyright remains Eric Young's, and as such any Copyright notices in |
| * the code are not to be removed. |
| * If this package is used in a product, Eric Young should be given attribution |
| * as the author of the parts of the library used. |
| * This can be in the form of a textual message at program startup or |
| * in documentation (online or textual) provided with the package. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. All advertising materials mentioning features or use of this software |
| * must display the following acknowledgement: |
| * "This product includes cryptographic software written by |
| * Eric Young (eay@cryptsoft.com)" |
| * The word 'cryptographic' can be left out if the rouines from the library |
| * being used are not cryptographic related :-). |
| * 4. If you include any Windows specific code (or a derivative thereof) from |
| * the apps directory (application code) you must include an acknowledgement: |
| * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
| * |
| * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * The licence and distribution terms for any publically available version or |
| * derivative of this code cannot be changed. i.e. this code cannot simply be |
| * copied and put under another distribution licence |
| * [including the GNU Public Licence.] */ |
| |
| #include <openssl/bn.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include <openssl/err.h> |
| |
| #include "internal.h" |
| |
| |
| int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) { |
| int i, nw, lb, rb; |
| BN_ULONG *t, *f; |
| BN_ULONG l; |
| |
| if (n < 0) { |
| OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER); |
| return 0; |
| } |
| |
| r->neg = a->neg; |
| nw = n / BN_BITS2; |
| if (!bn_wexpand(r, a->width + nw + 1)) { |
| return 0; |
| } |
| lb = n % BN_BITS2; |
| rb = BN_BITS2 - lb; |
| f = a->d; |
| t = r->d; |
| t[a->width + nw] = 0; |
| if (lb == 0) { |
| for (i = a->width - 1; i >= 0; i--) { |
| t[nw + i] = f[i]; |
| } |
| } else { |
| for (i = a->width - 1; i >= 0; i--) { |
| l = f[i]; |
| t[nw + i + 1] |= l >> rb; |
| t[nw + i] = l << lb; |
| } |
| } |
| OPENSSL_memset(t, 0, nw * sizeof(t[0])); |
| r->width = a->width + nw + 1; |
| bn_set_minimal_width(r); |
| |
| return 1; |
| } |
| |
| int BN_lshift1(BIGNUM *r, const BIGNUM *a) { |
| BN_ULONG *ap, *rp, t, c; |
| int i; |
| |
| if (r != a) { |
| r->neg = a->neg; |
| if (!bn_wexpand(r, a->width + 1)) { |
| return 0; |
| } |
| r->width = a->width; |
| } else { |
| if (!bn_wexpand(r, a->width + 1)) { |
| return 0; |
| } |
| } |
| ap = a->d; |
| rp = r->d; |
| c = 0; |
| for (i = 0; i < a->width; i++) { |
| t = *(ap++); |
| *(rp++) = (t << 1) | c; |
| c = t >> (BN_BITS2 - 1); |
| } |
| if (c) { |
| *rp = 1; |
| r->width++; |
| } |
| |
| return 1; |
| } |
| |
| void bn_rshift_words(BN_ULONG *r, const BN_ULONG *a, unsigned shift, |
| size_t num) { |
| unsigned shift_bits = shift % BN_BITS2; |
| size_t shift_words = shift / BN_BITS2; |
| if (shift_words >= num) { |
| OPENSSL_memset(r, 0, num * sizeof(BN_ULONG)); |
| return; |
| } |
| if (shift_bits == 0) { |
| OPENSSL_memmove(r, a + shift_words, (num - shift_words) * sizeof(BN_ULONG)); |
| } else { |
| for (size_t i = shift_words; i < num - 1; i++) { |
| r[i - shift_words] = |
| (a[i] >> shift_bits) | (a[i + 1] << (BN_BITS2 - shift_bits)); |
| } |
| r[num - 1 - shift_words] = a[num - 1] >> shift_bits; |
| } |
| OPENSSL_memset(r + num - shift_words, 0, shift_words * sizeof(BN_ULONG)); |
| } |
| |
| int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) { |
| if (n < 0) { |
| OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER); |
| return 0; |
| } |
| |
| if (!bn_wexpand(r, a->width)) { |
| return 0; |
| } |
| bn_rshift_words(r->d, a->d, n, a->width); |
| r->neg = a->neg; |
| r->width = a->width; |
| bn_set_minimal_width(r); |
| return 1; |
| } |
| |
| int bn_rshift_secret_shift(BIGNUM *r, const BIGNUM *a, unsigned n, |
| BN_CTX *ctx) { |
| int ret = 0; |
| BN_CTX_start(ctx); |
| BIGNUM *tmp = BN_CTX_get(ctx); |
| if (tmp == NULL || |
| !BN_copy(r, a) || |
| !bn_wexpand(tmp, r->width)) { |
| goto err; |
| } |
| |
| // Shift conditionally by powers of two. |
| unsigned max_bits = BN_BITS2 * r->width; |
| for (unsigned i = 0; (max_bits >> i) != 0; i++) { |
| BN_ULONG mask = (n >> i) & 1; |
| mask = 0 - mask; |
| bn_rshift_words(tmp->d, r->d, 1u << i, r->width); |
| bn_select_words(r->d, mask, tmp->d /* apply shift */, |
| r->d /* ignore shift */, r->width); |
| } |
| |
| ret = 1; |
| |
| err: |
| BN_CTX_end(ctx); |
| return ret; |
| } |
| |
| void bn_rshift1_words(BN_ULONG *r, const BN_ULONG *a, size_t num) { |
| if (num == 0) { |
| return; |
| } |
| for (size_t i = 0; i < num - 1; i++) { |
| r[i] = (a[i] >> 1) | (a[i + 1] << (BN_BITS2 - 1)); |
| } |
| r[num - 1] = a[num - 1] >> 1; |
| } |
| |
| int BN_rshift1(BIGNUM *r, const BIGNUM *a) { |
| if (!bn_wexpand(r, a->width)) { |
| return 0; |
| } |
| bn_rshift1_words(r->d, a->d, a->width); |
| r->width = a->width; |
| r->neg = a->neg; |
| bn_set_minimal_width(r); |
| return 1; |
| } |
| |
| int BN_set_bit(BIGNUM *a, int n) { |
| if (n < 0) { |
| return 0; |
| } |
| |
| int i = n / BN_BITS2; |
| int j = n % BN_BITS2; |
| if (a->width <= i) { |
| if (!bn_wexpand(a, i + 1)) { |
| return 0; |
| } |
| for (int k = a->width; k < i + 1; k++) { |
| a->d[k] = 0; |
| } |
| a->width = i + 1; |
| } |
| |
| a->d[i] |= (((BN_ULONG)1) << j); |
| |
| return 1; |
| } |
| |
| int BN_clear_bit(BIGNUM *a, int n) { |
| int i, j; |
| |
| if (n < 0) { |
| return 0; |
| } |
| |
| i = n / BN_BITS2; |
| j = n % BN_BITS2; |
| if (a->width <= i) { |
| return 0; |
| } |
| |
| a->d[i] &= (~(((BN_ULONG)1) << j)); |
| bn_set_minimal_width(a); |
| return 1; |
| } |
| |
| int bn_is_bit_set_words(const BN_ULONG *a, size_t num, unsigned bit) { |
| unsigned i = bit / BN_BITS2; |
| unsigned j = bit % BN_BITS2; |
| if (i >= num) { |
| return 0; |
| } |
| return (a[i] >> j) & 1; |
| } |
| |
| int BN_is_bit_set(const BIGNUM *a, int n) { |
| if (n < 0) { |
| return 0; |
| } |
| return bn_is_bit_set_words(a->d, a->width, n); |
| } |
| |
| int BN_mask_bits(BIGNUM *a, int n) { |
| if (n < 0) { |
| return 0; |
| } |
| |
| int w = n / BN_BITS2; |
| int b = n % BN_BITS2; |
| if (w >= a->width) { |
| return 1; |
| } |
| if (b == 0) { |
| a->width = w; |
| } else { |
| a->width = w + 1; |
| a->d[w] &= ~(BN_MASK2 << b); |
| } |
| |
| bn_set_minimal_width(a); |
| return 1; |
| } |
| |
| static int bn_count_low_zero_bits_word(BN_ULONG l) { |
| static_assert(sizeof(BN_ULONG) <= sizeof(crypto_word_t), |
| "crypto_word_t is too small"); |
| static_assert(sizeof(int) <= sizeof(crypto_word_t), |
| "crypto_word_t is too small"); |
| static_assert(BN_BITS2 == sizeof(BN_ULONG) * 8, "BN_ULONG has padding bits"); |
| // C has very bizarre rules for types smaller than an int. |
| static_assert(sizeof(BN_ULONG) >= sizeof(int), |
| "BN_ULONG gets promoted to int"); |
| |
| crypto_word_t mask; |
| int bits = 0; |
| |
| #if BN_BITS2 > 32 |
| // Check if the lower half of |x| are all zero. |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 32)); |
| // If the lower half is all zeros, it is included in the bit count and we |
| // count the upper half. Otherwise, we count the lower half. |
| bits += 32 & mask; |
| l = constant_time_select_w(mask, l >> 32, l); |
| #endif |
| |
| // The remaining blocks are analogous iterations at lower powers of two. |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 16)); |
| bits += 16 & mask; |
| l = constant_time_select_w(mask, l >> 16, l); |
| |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 8)); |
| bits += 8 & mask; |
| l = constant_time_select_w(mask, l >> 8, l); |
| |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 4)); |
| bits += 4 & mask; |
| l = constant_time_select_w(mask, l >> 4, l); |
| |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 2)); |
| bits += 2 & mask; |
| l = constant_time_select_w(mask, l >> 2, l); |
| |
| mask = constant_time_is_zero_w(l << (BN_BITS2 - 1)); |
| bits += 1 & mask; |
| |
| return bits; |
| } |
| |
| int BN_count_low_zero_bits(const BIGNUM *bn) { |
| static_assert(sizeof(BN_ULONG) <= sizeof(crypto_word_t), |
| "crypto_word_t is too small"); |
| static_assert(sizeof(int) <= sizeof(crypto_word_t), |
| "crypto_word_t is too small"); |
| |
| int ret = 0; |
| crypto_word_t saw_nonzero = 0; |
| for (int i = 0; i < bn->width; i++) { |
| crypto_word_t nonzero = ~constant_time_is_zero_w(bn->d[i]); |
| crypto_word_t first_nonzero = ~saw_nonzero & nonzero; |
| saw_nonzero |= nonzero; |
| |
| int bits = bn_count_low_zero_bits_word(bn->d[i]); |
| ret |= first_nonzero & (i * BN_BITS2 + bits); |
| } |
| |
| // If got to the end of |bn| and saw no non-zero words, |bn| is zero. |ret| |
| // will then remain zero. |
| return ret; |
| } |