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1 /* crypto/bn/bn_prime.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
58 /* ====================================================================
59 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
68 * 2. Redistributions in binary form must reproduce the above copyright
69 * notice, this list of conditions and the following disclaimer in
70 * the documentation and/or other materials provided with the
73 * 3. All advertising materials mentioning features or use of this
74 * software must display the following acknowledgment:
75 * "This product includes software developed by the OpenSSL Project
76 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
78 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
79 * endorse or promote products derived from this software without
80 * prior written permission. For written permission, please contact
81 * openssl-core@openssl.org.
83 * 5. Products derived from this software may not be called "OpenSSL"
84 * nor may "OpenSSL" appear in their names without prior written
85 * permission of the OpenSSL Project.
87 * 6. Redistributions of any form whatsoever must retain the following
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
92 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
93 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
95 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
96 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
97 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
98 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
99 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
101 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
103 * OF THE POSSIBILITY OF SUCH DAMAGE.
104 * ====================================================================
106 * This product includes cryptographic software written by Eric Young
107 * (eay@cryptsoft.com). This product includes software written by Tim
108 * Hudson (tjh@cryptsoft.com).
114 #include "cryptlib.h"
116 #include <openssl/rand.h>
118 /* The quick sieve algorithm approach to weeding out primes is
119 * Philip Zimmermann's, as implemented in PGP. I have had a read of
120 * his comments and implemented my own version.
122 #include "bn_prime.h"
124 static int witness(BIGNUM
*w
, const BIGNUM
*a
, const BIGNUM
*a1
,
125 const BIGNUM
*a1_odd
, int k
, BN_CTX
*ctx
, BN_MONT_CTX
*mont
);
126 static int probable_prime(BIGNUM
*rnd
, int bits
);
127 static int probable_prime_dh(BIGNUM
*rnd
, int bits
,
128 const BIGNUM
*add
, const BIGNUM
*rem
, BN_CTX
*ctx
);
129 static int probable_prime_dh_safe(BIGNUM
*rnd
, int bits
,
130 const BIGNUM
*add
, const BIGNUM
*rem
, BN_CTX
*ctx
);
132 BIGNUM
*BN_generate_prime(BIGNUM
*ret
, int bits
, int safe
,
133 const BIGNUM
*add
, const BIGNUM
*rem
,
134 void (*callback
)(int,int,void *), void *cb_arg
)
141 int checks
= BN_prime_checks_for_size(bits
);
144 if (ctx
== NULL
) goto err
;
147 if ((rnd
=BN_new()) == NULL
) goto err
;
153 /* make a random number and set the top and bottom bits */
156 if (!probable_prime(rnd
,bits
)) goto err
;
162 if (!probable_prime_dh_safe(rnd
,bits
,add
,rem
,ctx
))
167 if (!probable_prime_dh(rnd
,bits
,add
,rem
,ctx
))
171 /* if (BN_mod_word(rnd,(BN_ULONG)3) == 1) goto loop; */
172 if (callback
!= NULL
) callback(0,c1
++,cb_arg
);
176 i
=BN_is_prime_fasttest(rnd
,checks
,callback
,ctx
,cb_arg
,0);
177 if (i
== -1) goto err
;
178 if (i
== 0) goto loop
;
182 /* for "safe prime" generation,
183 * check that (p-1)/2 is prime.
184 * Since a prime is odd, We just
185 * need to divide by 2 */
186 if (!BN_rshift1(&t
,rnd
)) goto err
;
188 for (i
=0; i
<checks
; i
++)
190 j
=BN_is_prime_fasttest(rnd
,1,callback
,ctx
,cb_arg
,0);
191 if (j
== -1) goto err
;
192 if (j
== 0) goto loop
;
194 j
=BN_is_prime_fasttest(&t
,1,callback
,ctx
,cb_arg
,0);
195 if (j
== -1) goto err
;
196 if (j
== 0) goto loop
;
198 if (callback
!= NULL
) callback(2,c1
-1,cb_arg
);
199 /* We have a safe prime test pass */
202 /* we have a prime :-) */
205 if (!found
&& (ret
== NULL
) && (rnd
!= NULL
)) BN_free(rnd
);
207 if (ctx
!= NULL
) BN_CTX_free(ctx
);
208 return(found
? rnd
: NULL
);
211 int BN_is_prime(const BIGNUM
*a
, int checks
, void (*callback
)(int,int,void *),
212 BN_CTX
*ctx_passed
, void *cb_arg
)
214 return BN_is_prime_fasttest(a
, checks
, callback
, ctx_passed
, cb_arg
, 0);
217 int BN_is_prime_fasttest(const BIGNUM
*a
, int checks
,
218 void (*callback
)(int,int,void *),
219 BN_CTX
*ctx_passed
, void *cb_arg
,
220 int do_trial_division
)
225 BIGNUM
*A1
, *A1_odd
, *check
; /* taken from ctx */
226 BN_MONT_CTX
*mont
= NULL
;
227 const BIGNUM
*A
= NULL
;
229 if (checks
== BN_prime_checks
)
230 checks
= BN_prime_checks_for_size(BN_num_bits(a
));
232 /* first look for small factors */
235 if (do_trial_division
)
237 for (i
= 1; i
< NUMPRIMES
; i
++)
238 if (BN_mod_word(a
, primes
[i
]) == 0)
240 if (callback
!= NULL
) callback(1, -1, cb_arg
);
243 if (ctx_passed
!= NULL
)
246 if ((ctx
=BN_CTX_new()) == NULL
)
254 if ((t
= BN_CTX_get(ctx
)) == NULL
) goto err
;
261 A1
= BN_CTX_get(ctx
);
262 A1_odd
= BN_CTX_get(ctx
);
263 check
= BN_CTX_get(ctx
);
264 if (check
== NULL
) goto err
;
266 /* compute A1 := A - 1 */
269 if (!BN_sub_word(A1
, 1))
277 /* write A1 as A1_odd * 2^k */
279 while (!BN_is_bit_set(A1
, k
))
281 if (!BN_rshift(A1_odd
, A1
, k
))
284 /* Montgomery setup for computations mod A */
285 mont
= BN_MONT_CTX_new();
288 if (!BN_MONT_CTX_set(mont
, A
, ctx
))
291 for (i
= 0; i
< checks
; i
++)
293 if (!BN_pseudo_rand(check
, BN_num_bits(A1
), 0, 0))
295 if (BN_cmp(check
, A1
) >= 0)
296 if (!BN_sub(check
, check
, A1
))
298 if (!BN_add_word(check
, 1))
300 /* now 1 <= check < A */
302 j
= witness(check
, A
, A1
, A1_odd
, k
, ctx
, mont
);
303 if (j
== -1) goto err
;
309 if (callback
!= NULL
) callback(1,i
,cb_arg
);
316 if (ctx_passed
== NULL
)
320 BN_MONT_CTX_free(mont
);
325 static int witness(BIGNUM
*w
, const BIGNUM
*a
, const BIGNUM
*a1
,
326 const BIGNUM
*a1_odd
, int k
, BN_CTX
*ctx
, BN_MONT_CTX
*mont
)
328 if (!BN_mod_exp_mont(w
, w
, a1_odd
, a
, ctx
, mont
)) /* w := w^a1_odd mod a */
331 return 0; /* probably prime */
332 if (BN_cmp(w
, a1
) == 0)
333 return 0; /* w == -1 (mod a), 'a' is probably prime */
336 if (!BN_mod_mul(w
, w
, w
, a
, ctx
)) /* w := w^2 mod a */
339 return 1; /* 'a' is composite, otherwise a previous 'w' would
340 * have been == -1 (mod 'a') */
341 if (BN_cmp(w
, a1
) == 0)
342 return 0; /* w == -1 (mod a), 'a' is probably prime */
344 /* If we get here, 'w' is the (a-1)/2-th power of the original 'w',
345 * and it is neither -1 nor +1 -- so 'a' cannot be prime */
349 static int probable_prime(BIGNUM
*rnd
, int bits
)
352 BN_ULONG mods
[NUMPRIMES
];
356 if (!BN_rand(rnd
,bits
,1,1)) return(0);
357 /* we now have a random number 'rand' to test. */
358 for (i
=1; i
<NUMPRIMES
; i
++)
359 mods
[i
]=BN_mod_word(rnd
,(BN_ULONG
)primes
[i
]);
361 loop
: for (i
=1; i
<NUMPRIMES
; i
++)
363 /* check that rnd is not a prime and also
364 * that gcd(rnd-1,primes) == 1 (except for 2) */
365 if (((mods
[i
]+delta
)%primes
[i
]) <= 1)
369 /* perhaps need to check for overflow of
370 * delta (but delta can be up to 2^32)
371 * 21-May-98 eay - added overflow check */
372 if (delta
< d
) goto again
;
376 if (!BN_add_word(rnd
,delta
)) return(0);
380 static int probable_prime_dh(BIGNUM
*rnd
, int bits
,
381 const BIGNUM
*add
, const BIGNUM
*rem
, BN_CTX
*ctx
)
387 if ((t1
= BN_CTX_get(ctx
)) == NULL
) goto err
;
389 if (!BN_rand(rnd
,bits
,0,1)) goto err
;
391 /* we need ((rnd-rem) % add) == 0 */
393 if (!BN_mod(t1
,rnd
,add
,ctx
)) goto err
;
394 if (!BN_sub(rnd
,rnd
,t1
)) goto err
;
396 { if (!BN_add_word(rnd
,1)) goto err
; }
398 { if (!BN_add(rnd
,rnd
,rem
)) goto err
; }
400 /* we now have a random number 'rand' to test. */
402 loop
: for (i
=1; i
<NUMPRIMES
; i
++)
404 /* check that rnd is a prime */
405 if (BN_mod_word(rnd
,(BN_ULONG
)primes
[i
]) <= 1)
407 if (!BN_add(rnd
,rnd
,add
)) goto err
;
417 static int probable_prime_dh_safe(BIGNUM
*p
, int bits
, const BIGNUM
*padd
,
418 const BIGNUM
*rem
, BN_CTX
*ctx
)
425 t1
= BN_CTX_get(ctx
);
427 qadd
= BN_CTX_get(ctx
);
428 if (qadd
== NULL
) goto err
;
430 if (!BN_rshift1(qadd
,padd
)) goto err
;
432 if (!BN_rand(q
,bits
,0,1)) goto err
;
434 /* we need ((rnd-rem) % add) == 0 */
435 if (!BN_mod(t1
,q
,qadd
,ctx
)) goto err
;
436 if (!BN_sub(q
,q
,t1
)) goto err
;
438 { if (!BN_add_word(q
,1)) goto err
; }
441 if (!BN_rshift1(t1
,rem
)) goto err
;
442 if (!BN_add(q
,q
,t1
)) goto err
;
445 /* we now have a random number 'rand' to test. */
446 if (!BN_lshift1(p
,q
)) goto err
;
447 if (!BN_add_word(p
,1)) goto err
;
449 loop
: for (i
=1; i
<NUMPRIMES
; i
++)
451 /* check that p and q are prime */
452 /* check that for p and q
453 * gcd(p-1,primes) == 1 (except for 2) */
454 if ( (BN_mod_word(p
,(BN_ULONG
)primes
[i
]) == 0) ||
455 (BN_mod_word(q
,(BN_ULONG
)primes
[i
]) == 0))
457 if (!BN_add(p
,p
,padd
)) goto err
;
458 if (!BN_add(q
,q
,qadd
)) goto err
;