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1 | /* crypto/bn/bn_mont.c */ |
2 | /* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com) | |
3 | * All rights reserved. | |
4 | * | |
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. | |
8 | * | |
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). | |
15 | * | |
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. | |
22 | * | |
23 | * Redistribution and use in source and binary forms, with or without | |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
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)" | |
40 | * | |
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 | |
51 | * SUCH DAMAGE. | |
52 | * | |
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.] | |
57 | */ | |
58 | ||
59 | #include <stdio.h> | |
60 | #include "cryptlib.h" | |
61 | #include "bn_lcl.h" | |
62 | ||
63 | int BN_mod_mul_montgomery(r,a,b,mont,ctx) | |
64 | BIGNUM *r,*a,*b; | |
65 | BN_MONT_CTX *mont; | |
66 | BN_CTX *ctx; | |
67 | { | |
68 | BIGNUM *tmp; | |
69 | ||
70 | tmp=ctx->bn[ctx->tos++]; | |
71 | ||
72 | if (a == b) | |
73 | { | |
74 | if (!BN_sqr(tmp,a,ctx)) goto err; | |
75 | } | |
76 | else | |
77 | { | |
78 | if (!BN_mul(tmp,a,b)) goto err; | |
79 | } | |
80 | /* reduce from aRR to aR */ | |
81 | if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err; | |
82 | ctx->tos--; | |
83 | return(1); | |
84 | err: | |
85 | return(0); | |
86 | } | |
87 | ||
88 | #define MONT_WORD | |
89 | ||
90 | #ifdef MONT_WORD | |
91 | int BN_from_montgomery(ret,a,mont,ctx) | |
92 | BIGNUM *ret; | |
93 | BIGNUM *a; | |
94 | BN_MONT_CTX *mont; | |
95 | BN_CTX *ctx; | |
96 | { | |
97 | BIGNUM *n,*t1,*r; | |
98 | BN_ULONG *ap,*np,*rp,k,n0,v,v2; | |
99 | int al,nl,max,i,x; | |
100 | int retn=0; | |
101 | ||
102 | t1=ctx->bn[ctx->tos]; | |
103 | r=ctx->bn[ctx->tos+1]; | |
104 | ||
105 | if (!BN_copy(r,a)) goto err; | |
106 | n=mont->N; | |
107 | ||
108 | if (!BN_copy(t1,a)) goto err; | |
109 | BN_mask_bits(t1,mont->ri); | |
110 | ||
111 | a=t1; | |
112 | ||
113 | al=a->top; | |
114 | nl=n->top; | |
115 | if ((al == 0) || (nl == 0)) { r->top=0; return(1); } | |
116 | ||
117 | max=(nl+al+1); /* allow for overflow (no?) XXX */ | |
118 | if (bn_expand(r,(max)*BN_BITS2) == NULL) goto err; | |
119 | ||
120 | r->neg=a->neg^n->neg; | |
121 | ap=a->d; | |
122 | np=n->d; | |
123 | rp=r->d; | |
124 | ||
125 | /* clear the top bytes of T */ | |
126 | for (i=r->top; i<max; i++) /* memset? XXX */ | |
127 | r->d[i]=0; | |
128 | /* memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); */ | |
129 | ||
130 | r->top=max; | |
131 | n0=mont->n0; | |
132 | ||
133 | for (i=0; i<nl; i++) | |
134 | { | |
135 | /* This is were part words probably goes wrong */ | |
136 | k=(rp[0]*n0)&BN_MASK2; | |
137 | v=bn_mul_add_word(rp,np,nl,k); | |
138 | ||
139 | for (x=nl; v; x++) | |
140 | { | |
141 | v2=rp[x]; | |
142 | v2+=v; | |
143 | rp[x]=v2; | |
144 | v=((v2&BN_MASK2) < v)?1:0; /* ever true? XXX */ | |
145 | } | |
146 | rp++; | |
147 | } | |
148 | while (r->d[r->top-1] == 0) | |
149 | r->top--; | |
150 | ||
151 | BN_rshift(ret,r,mont->ri); | |
152 | ||
153 | if (BN_ucmp(ret,mont->N) >= 0) | |
154 | { | |
155 | bn_qsub(ret,ret,mont->N); /* XXX */ | |
156 | } | |
157 | retn=1; | |
158 | err: | |
159 | return(retn); | |
160 | } | |
161 | #else | |
162 | int BN_from_montgomery(r,a,mont,ctx) | |
163 | BIGNUM *r; | |
164 | BIGNUM *a; | |
165 | BN_MONT_CTX *mont; | |
166 | BN_CTX *ctx; | |
167 | { | |
168 | BIGNUM *t1,*t2; | |
169 | ||
170 | t1=ctx->bn[ctx->tos]; | |
171 | t2=ctx->bn[ctx->tos+1]; | |
172 | ||
173 | if (!BN_copy(t1,a)) goto err; | |
174 | /* can cheat */ | |
175 | BN_mask_bits(t1,mont->ri); | |
176 | ||
177 | if (!BN_mul(t2,t1,mont->Ni)) goto err; | |
178 | BN_mask_bits(t2,mont->ri); | |
179 | ||
180 | if (!BN_mul(t1,t2,mont->N)) goto err; | |
181 | if (!BN_add(t2,a,t1)) goto err; | |
182 | BN_rshift(r,t2,mont->ri); | |
183 | ||
184 | if (BN_ucmp(r,mont->N) >= 0) | |
185 | bn_qsub(r,r,mont->N); | |
186 | ||
187 | return(1); | |
188 | err: | |
189 | return(0); | |
190 | } | |
191 | #endif | |
192 | ||
193 | BN_MONT_CTX *BN_MONT_CTX_new() | |
194 | { | |
195 | BN_MONT_CTX *ret; | |
196 | ||
197 | if ((ret=(BN_MONT_CTX *)Malloc(sizeof(BN_MONT_CTX))) == NULL) | |
198 | return(NULL); | |
199 | ret->ri=0; | |
200 | ret->RR=BN_new(); | |
201 | ret->N=BN_new(); | |
202 | ret->Ni=NULL; | |
203 | if ((ret->RR == NULL) || (ret->N == NULL)) | |
204 | { | |
205 | BN_MONT_CTX_free(ret); | |
206 | return(NULL); | |
207 | } | |
208 | return(ret); | |
209 | } | |
210 | ||
211 | void BN_MONT_CTX_free(mont) | |
212 | BN_MONT_CTX *mont; | |
213 | { | |
214 | if (mont->RR != NULL) BN_free(mont->RR); | |
215 | if (mont->N != NULL) BN_free(mont->N); | |
216 | if (mont->Ni != NULL) BN_free(mont->Ni); | |
217 | Free(mont); | |
218 | } | |
219 | ||
220 | int BN_MONT_CTX_set(mont,mod,ctx) | |
221 | BN_MONT_CTX *mont; | |
222 | BIGNUM *mod; | |
223 | BN_CTX *ctx; | |
224 | { | |
225 | BIGNUM *Ri=NULL,*R=NULL; | |
226 | ||
227 | if (mont->RR == NULL) mont->RR=BN_new(); | |
228 | if (mont->N == NULL) mont->N=BN_new(); | |
229 | ||
230 | R=mont->RR; /* grab RR as a temp */ | |
231 | BN_copy(mont->N,mod); /* Set N */ | |
232 | ||
233 | #ifdef MONT_WORD | |
234 | { | |
235 | BIGNUM tmod; | |
236 | BN_ULONG buf[2]; | |
237 | /* int z; */ | |
238 | ||
239 | mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2; | |
240 | BN_lshift(R,BN_value_one(),BN_BITS2); /* R */ | |
241 | /* I was bad, this modification of a passed variable was | |
242 | * breaking the multithreaded stuff :-( | |
243 | * z=mod->top; | |
244 | * mod->top=1; */ | |
245 | ||
246 | buf[0]=mod->d[0]; | |
247 | buf[1]=0; | |
248 | tmod.d=buf; | |
249 | tmod.top=1; | |
250 | tmod.max=mod->max; | |
251 | tmod.neg=mod->neg; | |
252 | ||
253 | if ((Ri=BN_mod_inverse(R,&tmod,ctx)) == NULL) goto err; /* Ri */ | |
254 | BN_lshift(Ri,Ri,BN_BITS2); /* R*Ri */ | |
255 | bn_qsub(Ri,Ri,BN_value_one()); /* R*Ri - 1 */ | |
256 | BN_div(Ri,NULL,Ri,&tmod,ctx); | |
257 | mont->n0=Ri->d[0]; | |
258 | BN_free(Ri); | |
259 | /* mod->top=z; */ | |
260 | } | |
261 | #else | |
262 | mont->ri=BN_num_bits(mod); | |
263 | BN_lshift(R,BN_value_one(),mont->ri); /* R */ | |
264 | if ((Ri=BN_mod_inverse(R,mod,ctx)) == NULL) goto err; /* Ri */ | |
265 | BN_lshift(Ri,Ri,mont->ri); /* R*Ri */ | |
266 | bn_qsub(Ri,Ri,BN_value_one()); /* R*Ri - 1 */ | |
267 | BN_div(Ri,NULL,Ri,mod,ctx); | |
268 | if (mont->Ni != NULL) BN_free(mont->Ni); | |
269 | mont->Ni=Ri; /* Ni=(R*Ri-1)/N */ | |
270 | #endif | |
271 | ||
272 | /* setup RR for conversions */ | |
273 | BN_lshift(mont->RR,BN_value_one(),mont->ri*2); | |
274 | BN_mod(mont->RR,mont->RR,mont->N,ctx); | |
275 | ||
276 | return(1); | |
277 | err: | |
278 | return(0); | |
279 | } | |
280 |