1 /* ====================================================================
2 * Copyright (c) 1998-2014 The OpenSSL Project. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
16 * 3. All advertising materials mentioning features or use of this
17 * software must display the following acknowledgment:
18 * "This product includes software developed by the OpenSSL Project
19 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
22 * endorse or promote products derived from this software without
23 * prior written permission. For written permission, please contact
24 * openssl-core@openssl.org.
26 * 5. Products derived from this software may not be called "OpenSSL"
27 * nor may "OpenSSL" appear in their names without prior written
28 * permission of the OpenSSL Project.
30 * 6. Redistributions of any form whatsoever must retain the following
32 * "This product includes software developed by the OpenSSL Project
33 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
36 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
38 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
39 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
41 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
42 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
44 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
45 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
46 * OF THE POSSIBILITY OF SUCH DAMAGE.
47 * ====================================================================
49 * This product includes cryptographic software written by Eric Young
50 * (eay@cryptsoft.com). This product includes software written by Tim
51 * Hudson (tjh@cryptsoft.com).
59 * Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'.
60 * This is an array r[] of values that are either zero or odd with an
61 * absolute value less than 2^w satisfying
62 * scalar = \sum_j r[j]*2^j
63 * where at most one of any w+1 consecutive digits is non-zero
64 * with the exception that the most significant digit may be only
65 * w-1 zeros away from that next non-zero digit.
67 signed char *bn_compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
71 signed char *r = NULL;
73 int bit, next_bit, mask;
76 if (BN_is_zero(scalar)) {
77 r = OPENSSL_malloc(1);
79 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
87 if (w <= 0 || w > 7) { /* 'signed char' can represent integers with absolute values less than 2^7 */
88 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
91 bit = 1 << w; /* at most 128 */
92 next_bit = bit << 1; /* at most 256 */
93 mask = next_bit - 1; /* at most 255 */
95 if (BN_is_negative(scalar)) {
99 if (scalar->d == NULL || scalar->top == 0) {
100 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
104 len = BN_num_bits(scalar);
105 r = OPENSSL_malloc(len + 1); /*
106 * Modified wNAF may be one digit longer than binary representation
107 * (*ret_len will be set to the actual length, i.e. at most
108 * BN_num_bits(scalar) + 1)
111 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
114 window_val = scalar->d[0] & mask;
116 while ((window_val != 0) || (j + w + 1 < len)) { /* if j+w+1 >= len, window_val will not increase */
119 /* 0 <= window_val <= 2^(w+1) */
121 if (window_val & 1) {
122 /* 0 < window_val < 2^(w+1) */
124 if (window_val & bit) {
125 digit = window_val - next_bit; /* -2^w < digit < 0 */
127 #if 1 /* modified wNAF */
128 if (j + w + 1 >= len) {
130 * Special case for generating modified wNAFs:
131 * no new bits will be added into window_val,
132 * so using a positive digit here will decrease
133 * the total length of the representation
136 digit = window_val & (mask >> 1); /* 0 < digit < 2^w */
140 digit = window_val; /* 0 < digit < 2^w */
143 if (digit <= -bit || digit >= bit || !(digit & 1)) {
144 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
150 /* now window_val is 0 or 2^(w+1) in standard wNAF generation;
151 * for modified window NAFs, it may also be 2^w
153 if (window_val != 0 && window_val != next_bit && window_val != bit) {
154 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
159 r[j++] = sign * digit;
162 window_val += bit * BN_is_bit_set(scalar, j + w);
164 if (window_val > next_bit) {
165 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
171 BNerr(BN_F_BN_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
187 int bn_get_top(const BIGNUM *a)
192 void bn_set_top(BIGNUM *a, int top)
197 int bn_get_dmax(const BIGNUM *a)
202 void bn_set_all_zero(BIGNUM *a)
206 for (i = a->top; i < a->dmax; i++) a->d[i] = 0;
209 int bn_copy_words(BN_ULONG *out, const BIGNUM *in, int size)
214 memset(out, 0, sizeof(BN_ULONG) * size);
215 memcpy(out, in->d, sizeof(BN_ULONG) * in->top);
219 BN_ULONG *bn_get_words(const BIGNUM *a)
224 void bn_set_static_words(BIGNUM *a, BN_ULONG *words, int size)
227 a->dmax = a->top = size;
229 a->flags |= BN_FLG_STATIC_DATA;
232 void bn_set_data(BIGNUM *a, const void *data, size_t size)
234 memcpy(a->d, data, size);
237 size_t bn_sizeof_BIGNUM(void)
239 return sizeof(BIGNUM);
242 BIGNUM *bn_array_el(BIGNUM *base, int el)