Coverage Report

Created: 2024-11-21 06:47

/src/openssl/crypto/bn/bn_sqr.c
Line
Count
Source (jump to first uncovered line)
1
/*
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 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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 *
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 * Licensed under the Apache License 2.0 (the "License").  You may not use
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 * this file except in compliance with the License.  You can obtain a copy
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 * in the file LICENSE in the source distribution or at
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 * https://www.openssl.org/source/license.html
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 */
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10
#include "internal/cryptlib.h"
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#include "bn_local.h"
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13
/* r must not be a */
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/*
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 * I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96
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 */
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int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
18
12.6M
{
19
12.6M
    int ret = bn_sqr_fixed_top(r, a, ctx);
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21
12.6M
    bn_correct_top(r);
22
12.6M
    bn_check_top(r);
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12.6M
    return ret;
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12.6M
}
26
27
int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
28
13.7M
{
29
13.7M
    int max, al;
30
13.7M
    int ret = 0;
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13.7M
    BIGNUM *tmp, *rr;
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33
13.7M
    bn_check_top(a);
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35
13.7M
    al = a->top;
36
13.7M
    if (al <= 0) {
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103k
        r->top = 0;
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103k
        r->neg = 0;
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103k
        return 1;
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103k
    }
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42
13.6M
    BN_CTX_start(ctx);
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13.6M
    rr = (a != r) ? r : BN_CTX_get(ctx);
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13.6M
    tmp = BN_CTX_get(ctx);
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13.6M
    if (rr == NULL || tmp == NULL)
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0
        goto err;
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13.6M
    max = 2 * al;               /* Non-zero (from above) */
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13.6M
    if (bn_wexpand(rr, max) == NULL)
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0
        goto err;
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13.6M
    if (al == 4) {
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#ifndef BN_SQR_COMBA
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        BN_ULONG t[8];
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        bn_sqr_normal(rr->d, a->d, 4, t);
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#else
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45.1k
        bn_sqr_comba4(rr->d, a->d);
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45.1k
#endif
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13.5M
    } else if (al == 8) {
60
#ifndef BN_SQR_COMBA
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        BN_ULONG t[16];
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        bn_sqr_normal(rr->d, a->d, 8, t);
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#else
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196k
        bn_sqr_comba8(rr->d, a->d);
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196k
#endif
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13.3M
    } else {
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13.3M
#if defined(BN_RECURSION)
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13.3M
        if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
69
1.56M
            BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
70
1.56M
            bn_sqr_normal(rr->d, a->d, al, t);
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11.8M
        } else {
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11.8M
            int j, k;
73
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11.8M
            j = BN_num_bits_word((BN_ULONG)al);
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11.8M
            j = 1 << (j - 1);
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11.8M
            k = j + j;
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11.8M
            if (al == j) {
78
639k
                if (bn_wexpand(tmp, k * 2) == NULL)
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0
                    goto err;
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639k
                bn_sqr_recursive(rr->d, a->d, al, tmp->d);
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11.1M
            } else {
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11.1M
                if (bn_wexpand(tmp, max) == NULL)
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0
                    goto err;
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11.1M
                bn_sqr_normal(rr->d, a->d, al, tmp->d);
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11.1M
            }
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11.8M
        }
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#else
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        if (bn_wexpand(tmp, max) == NULL)
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            goto err;
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        bn_sqr_normal(rr->d, a->d, al, tmp->d);
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#endif
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13.3M
    }
93
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13.6M
    rr->neg = 0;
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13.6M
    rr->top = max;
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13.6M
    rr->flags |= BN_FLG_FIXED_TOP;
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13.6M
    if (r != rr && BN_copy(r, rr) == NULL)
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0
        goto err;
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100
13.6M
    ret = 1;
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13.6M
 err:
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13.6M
    bn_check_top(rr);
103
13.6M
    bn_check_top(tmp);
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13.6M
    BN_CTX_end(ctx);
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13.6M
    return ret;
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13.6M
}
107
108
/* tmp must have 2*n words */
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void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
110
12.7M
{
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12.7M
    int i, j, max;
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12.7M
    const BN_ULONG *ap;
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12.7M
    BN_ULONG *rp;
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115
12.7M
    max = n * 2;
116
12.7M
    ap = a;
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12.7M
    rp = r;
118
12.7M
    rp[0] = rp[max - 1] = 0;
119
12.7M
    rp++;
120
12.7M
    j = n;
121
122
12.7M
    if (--j > 0) {
123
11.3M
        ap++;
124
11.3M
        rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
125
11.3M
        rp += 2;
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11.3M
    }
127
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582M
    for (i = n - 2; i > 0; i--) {
129
569M
        j--;
130
569M
        ap++;
131
569M
        rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
132
569M
        rp += 2;
133
569M
    }
134
135
12.7M
    bn_add_words(r, r, r, max);
136
137
    /* There will not be a carry */
138
139
12.7M
    bn_sqr_words(tmp, a, n);
140
141
12.7M
    bn_add_words(r, r, tmp, max);
142
12.7M
}
143
144
#ifdef BN_RECURSION
145
/*-
146
 * r is 2*n words in size,
147
 * a and b are both n words in size.    (There's not actually a 'b' here ...)
148
 * n must be a power of 2.
149
 * We multiply and return the result.
150
 * t must be 2*n words in size
151
 * We calculate
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 * a[0]*b[0]
153
 * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
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 * a[1]*b[1]
155
 */
156
void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
157
7.62M
{
158
7.62M
    int n = n2 / 2;
159
7.62M
    int zero, c1;
160
7.62M
    BN_ULONG ln, lo, *p;
161
162
7.62M
    if (n2 == 4) {
163
# ifndef BN_SQR_COMBA
164
        bn_sqr_normal(r, a, 4, t);
165
# else
166
0
        bn_sqr_comba4(r, a);
167
0
# endif
168
0
        return;
169
7.62M
    } else if (n2 == 8) {
170
# ifndef BN_SQR_COMBA
171
        bn_sqr_normal(r, a, 8, t);
172
# else
173
5.29M
        bn_sqr_comba8(r, a);
174
5.29M
# endif
175
5.29M
        return;
176
5.29M
    }
177
2.32M
    if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
178
0
        bn_sqr_normal(r, a, n2, t);
179
0
        return;
180
0
    }
181
    /* r=(a[0]-a[1])*(a[1]-a[0]) */
182
2.32M
    c1 = bn_cmp_words(a, &(a[n]), n);
183
2.32M
    zero = 0;
184
2.32M
    if (c1 > 0)
185
1.77M
        bn_sub_words(t, a, &(a[n]), n);
186
556k
    else if (c1 < 0)
187
549k
        bn_sub_words(t, &(a[n]), a, n);
188
6.55k
    else
189
6.55k
        zero = 1;
190
191
    /* The result will always be negative unless it is zero */
192
2.32M
    p = &(t[n2 * 2]);
193
194
2.32M
    if (!zero)
195
2.32M
        bn_sqr_recursive(&(t[n2]), t, n, p);
196
6.55k
    else
197
6.55k
        memset(&t[n2], 0, sizeof(*t) * n2);
198
2.32M
    bn_sqr_recursive(r, a, n, p);
199
2.32M
    bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
200
201
    /*-
202
     * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
203
     * r[10] holds (a[0]*b[0])
204
     * r[32] holds (b[1]*b[1])
205
     */
206
207
2.32M
    c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
208
209
    /* t[32] is negative */
210
2.32M
    c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
211
212
    /*-
213
     * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
214
     * r[10] holds (a[0]*a[0])
215
     * r[32] holds (a[1]*a[1])
216
     * c1 holds the carry bits
217
     */
218
2.32M
    c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
219
2.32M
    if (c1) {
220
474k
        p = &(r[n + n2]);
221
474k
        lo = *p;
222
474k
        ln = (lo + c1) & BN_MASK2;
223
474k
        *p = ln;
224
225
        /*
226
         * The overflow will stop before we over write words we should not
227
         * overwrite
228
         */
229
474k
        if (ln < (BN_ULONG)c1) {
230
19.6k
            do {
231
19.6k
                p++;
232
19.6k
                lo = *p;
233
19.6k
                ln = (lo + 1) & BN_MASK2;
234
19.6k
                *p = ln;
235
19.6k
            } while (ln == 0);
236
9.84k
        }
237
474k
    }
238
2.32M
}
239
#endif