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git.ipfire.org Git - thirdparty/openssl.git/blob - crypto/bn/bn_mont.c
1 /* crypto/bn/bn_mont.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.]
60 * Details about Montgomery multiplication algorithms can be found at
61 * http://security.ece.orst.edu/publications.html, e.g.
62 * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
63 * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
70 #define MONT_WORD /* use the faster word-based algorithm */
72 int BN_mod_mul_montgomery(BIGNUM
*r
, BIGNUM
*a
, BIGNUM
*b
,
73 BN_MONT_CTX
*mont
, BN_CTX
*ctx
)
79 tmp
= BN_CTX_get(ctx
);
80 tmp2
= BN_CTX_get(ctx
);
81 if (tmp
== NULL
|| tmp2
== NULL
) goto err
;
89 bn_wexpand(tmp
,a
->top
*2);
90 bn_wexpand(tmp2
,a
->top
*4);
91 bn_sqr_recursive(tmp
->d
,a
->d
,a
->top
,tmp2
->d
);
93 if (tmp
->top
> 0 && tmp
->d
[tmp
->top
-1] == 0)
96 if (!BN_sqr(tmp
,a
,ctx
)) goto err
;
101 if (!BN_mul(tmp
,a
,b
,ctx
)) goto err
;
103 /* reduce from aRR to aR */
104 if (!BN_from_montgomery(r
,tmp
,mont
,ctx
)) goto err
;
111 int BN_from_montgomery(BIGNUM
*ret
, BIGNUM
*a
, BN_MONT_CTX
*mont
,
118 BN_ULONG
*ap
,*np
,*rp
,n0
,v
,*nrp
;
119 int al
,nl
,max
,i
,x
,ri
;
122 if ((r
= BN_CTX_get(ctx
)) == NULL
) goto err
;
124 if (!BN_copy(r
,a
)) goto err
;
128 /* mont->ri is the size of mont->N in bits (rounded up
130 al
=ri
=mont
->ri
/BN_BITS2
;
133 if ((al
== 0) || (nl
== 0)) { r
->top
=0; return(1); }
135 max
=(nl
+al
+1); /* allow for overflow (no?) XXX */
136 if (bn_wexpand(r
,max
) == NULL
) goto err
;
137 if (bn_wexpand(ret
,max
) == NULL
) goto err
;
139 r
->neg
=a
->neg
^n
->neg
;
144 /* clear the top words of T */
146 for (i
=r
->top
; i
<max
; i
++) /* memset? XXX */
149 memset(&(r
->d
[r
->top
]),0,(max
-r
->top
)*sizeof(BN_ULONG
));
156 printf("word BN_from_montgomery %d * %d\n",nl
,nl
);
165 t1
= rp
[0] * (n0
& 0177777);
168 t3
= rp
[0] & 0177777;
169 t2
= (t3
* t2
) & BN_MASK2
;
171 v
=bn_mul_add_words(rp
,np
,nl
,(BN_ULONG
) t1
);
174 v
=bn_mul_add_words(rp
,np
,nl
,(rp
[0]*n0
)&BN_MASK2
);
178 if (((nrp
[-1]+=v
)&BN_MASK2
) >= v
)
182 if (((++nrp
[0])&BN_MASK2
) != 0) continue;
183 if (((++nrp
[1])&BN_MASK2
) != 0) continue;
184 for (x
=2; (((++nrp
[x
])&BN_MASK2
) == 0); x
++) ;
189 /* mont->ri will be a multiple of the word size */
191 BN_rshift(ret
,r
,mont
->ri
);
202 for (i
=0; i
<al
; i
+=4)
204 BN_ULONG t1
,t2
,t3
,t4
;
219 #else /* !MONT_WORD */
223 t1
= BN_CTX_get(ctx
);
224 t2
= BN_CTX_get(ctx
);
225 if (t1
== NULL
|| t2
== NULL
) goto err
;
227 if (!BN_copy(t1
,a
)) goto err
;
228 BN_mask_bits(t1
,mont
->ri
);
230 if (!BN_mul(t2
,t1
,&mont
->Ni
,ctx
)) goto err
;
231 BN_mask_bits(t2
,mont
->ri
);
233 if (!BN_mul(t1
,t2
,&mont
->N
,ctx
)) goto err
;
234 if (!BN_add(t2
,a
,t1
)) goto err
;
235 BN_rshift(ret
,t2
,mont
->ri
);
236 #endif /* MONT_WORD */
238 if (BN_ucmp(ret
, &(mont
->N
)) >= 0)
240 BN_usub(ret
,ret
,&(mont
->N
));
248 BN_MONT_CTX
*BN_MONT_CTX_new(void)
252 if ((ret
=(BN_MONT_CTX
*)OPENSSL_malloc(sizeof(BN_MONT_CTX
))) == NULL
)
255 BN_MONT_CTX_init(ret
);
256 ret
->flags
=BN_FLG_MALLOCED
;
260 void BN_MONT_CTX_init(BN_MONT_CTX
*ctx
)
269 void BN_MONT_CTX_free(BN_MONT_CTX
*mont
)
274 BN_free(&(mont
->RR
));
276 BN_free(&(mont
->Ni
));
277 if (mont
->flags
& BN_FLG_MALLOCED
)
281 int BN_MONT_CTX_set(BN_MONT_CTX
*mont
, const BIGNUM
*mod
, BN_CTX
*ctx
)
286 R
= &(mont
->RR
); /* grab RR as a temp */
287 BN_copy(&(mont
->N
),mod
); /* Set N */
294 mont
->ri
=(BN_num_bits(mod
)+(BN_BITS2
-1))/BN_BITS2
*BN_BITS2
;
296 BN_set_bit(R
,BN_BITS2
); /* R */
298 buf
[0]=mod
->d
[0]; /* tmod = N mod word size */
305 if ((BN_mod_inverse(&Ri
,R
,&tmod
,ctx
)) == NULL
)
307 BN_lshift(&Ri
,&Ri
,BN_BITS2
); /* R*Ri */
308 if (!BN_is_zero(&Ri
))
310 else /* if N mod word size == 1 */
311 BN_set_word(&Ri
,BN_MASK2
); /* Ri-- (mod word size) */
312 BN_div(&Ri
,NULL
,&Ri
,&tmod
,ctx
); /* Ni = (R*Ri-1)/N,
313 * keep only least significant word: */
317 #else /* !MONT_WORD */
318 { /* bignum version */
319 mont
->ri
=BN_num_bits(mod
);
321 BN_set_bit(R
,mont
->ri
); /* R = 2^ri */
323 if ((BN_mod_inverse(&Ri
,R
,mod
,ctx
)) == NULL
)
325 BN_lshift(&Ri
,&Ri
,mont
->ri
); /* R*Ri */
327 /* Ni = (R*Ri-1) / N */
328 BN_div(&(mont
->Ni
),NULL
,&Ri
,mod
,ctx
);
333 /* setup RR for conversions */
334 BN_zero(&(mont
->RR
));
335 BN_set_bit(&(mont
->RR
),mont
->ri
*2);
336 BN_mod(&(mont
->RR
),&(mont
->RR
),&(mont
->N
),ctx
);
343 BN_MONT_CTX
*BN_MONT_CTX_copy(BN_MONT_CTX
*to
, BN_MONT_CTX
*from
)
345 if (to
== from
) return(to
);
347 BN_copy(&(to
->RR
),&(from
->RR
));
348 BN_copy(&(to
->N
),&(from
->N
));
349 BN_copy(&(to
->Ni
),&(from
->Ni
));