1 /* crypto/bn/bn_exp.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) 1998-2005 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).
113 #include "cryptlib.h"
120 # define alloca _alloca
122 #elif defined(__GNUC__)
124 # define alloca(s) __builtin_alloca((s))
128 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
129 # include "sparc_arch.h"
130 extern unsigned int OPENSSL_sparcv9cap_P[];
133 /* maximum precomputation table size for *variable* sliding windows */
134 #define TABLE_SIZE 32
136 /* this one works - simple but works */
137 int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
142 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
144 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
145 BNerr(BN_F_BN_EXP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
150 if ((r == a) || (r == p))
151 rr = BN_CTX_get(ctx);
155 if (rr == NULL || v == NULL) goto err;
157 if (BN_copy(v,a) == NULL) goto err;
161 { if (BN_copy(rr,a) == NULL) goto err; }
162 else { if (!BN_one(rr)) goto err; }
164 for (i=1; i<bits; i++)
166 if (!BN_sqr(v,v,ctx)) goto err;
167 if (BN_is_bit_set(p,i))
169 if (!BN_mul(rr,rr,v,ctx)) goto err;
174 if (r != rr) BN_copy(r,rr);
181 int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
190 /* For even modulus m = 2^k*m_odd, it might make sense to compute
191 * a^p mod m_odd and a^p mod 2^k separately (with Montgomery
192 * exponentiation for the odd part), using appropriate exponent
193 * reductions, and combine the results using the CRT.
195 * For now, we use Montgomery only if the modulus is odd; otherwise,
196 * exponentiation using the reciprocal-based quick remaindering
199 * (Timing obtained with expspeed.c [computations a^p mod m
200 * where a, p, m are of the same length: 256, 512, 1024, 2048,
201 * 4096, 8192 bits], compared to the running time of the
202 * standard algorithm:
204 * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration]
205 * 55 .. 77 % [UltraSparc processor, but
206 * debug-solaris-sparcv8-gcc conf.]
208 * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration]
209 * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc]
211 * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont
212 * at 2048 and more bits, but at 512 and 1024 bits, it was
213 * slower even than the standard algorithm!
215 * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations]
216 * should be obtained when the new Montgomery reduction code
217 * has been integrated into OpenSSL.)
221 #define MONT_EXP_WORD
225 /* I have finally been able to take out this pre-condition of
226 * the top bit being set. It was caused by an error in BN_div
227 * with negatives. There was also another problem when for a^b%m
228 * a >= m. eay 07-May-97 */
229 /* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */
233 # ifdef MONT_EXP_WORD
234 if (a->top == 1 && !a->neg && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0))
236 BN_ULONG A = a->d[0];
237 ret=BN_mod_exp_mont_word(r,A,p,m,ctx,NULL);
241 ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL);
246 { ret=BN_mod_exp_recp(r,a,p,m,ctx); }
248 { ret=BN_mod_exp_simple(r,a,p,m,ctx); }
256 int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
257 const BIGNUM *m, BN_CTX *ctx)
259 int i,j,bits,ret=0,wstart,wend,window,wvalue;
262 /* Table of variables obtained from 'ctx' */
263 BIGNUM *val[TABLE_SIZE];
266 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
268 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
269 BNerr(BN_F_BN_MOD_EXP_RECP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
282 aa = BN_CTX_get(ctx);
283 val[0] = BN_CTX_get(ctx);
284 if(!aa || !val[0]) goto err;
286 BN_RECP_CTX_init(&recp);
289 /* ignore sign of 'm' */
290 if (!BN_copy(aa, m)) goto err;
292 if (BN_RECP_CTX_set(&recp,aa,ctx) <= 0) goto err;
296 if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;
299 if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */
300 if (BN_is_zero(val[0]))
307 window = BN_window_bits_for_exponent_size(bits);
310 if (!BN_mod_mul_reciprocal(aa,val[0],val[0],&recp,ctx))
315 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
316 !BN_mod_mul_reciprocal(val[i],val[i-1],
322 start=1; /* This is used to avoid multiplication etc
323 * when there is only the value '1' in the
325 wvalue=0; /* The 'value' of the window */
326 wstart=bits-1; /* The top bit of the window */
327 wend=0; /* The bottom bit of the window */
329 if (!BN_one(r)) goto err;
333 if (BN_is_bit_set(p,wstart) == 0)
336 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
338 if (wstart == 0) break;
342 /* We now have wstart on a 'set' bit, we now need to work out
343 * how bit a window to do. To do this we need to scan
344 * forward until the last set bit before the end of the
349 for (i=1; i<window; i++)
351 if (wstart-i < 0) break;
352 if (BN_is_bit_set(p,wstart-i))
360 /* wend is the size of the current window */
362 /* add the 'bytes above' */
366 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
370 /* wvalue will be an odd number < 2^window */
371 if (!BN_mod_mul_reciprocal(r,r,val[wvalue>>1],&recp,ctx))
374 /* move the 'window' down further */
378 if (wstart < 0) break;
383 BN_RECP_CTX_free(&recp);
389 int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
390 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
392 int i,j,bits,ret=0,wstart,wend,window,wvalue;
396 /* Table of variables obtained from 'ctx' */
397 BIGNUM *val[TABLE_SIZE];
398 BN_MONT_CTX *mont=NULL;
400 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
402 return BN_mod_exp_mont_consttime(rr, a, p, m, ctx, in_mont);
411 BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
424 val[0] = BN_CTX_get(ctx);
425 if (!d || !r || !val[0]) goto err;
427 /* If this is not done, things will break in the montgomery
434 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
435 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
438 if (a->neg || BN_ucmp(a,m) >= 0)
440 if (!BN_nnmod(val[0],a,m,ctx))
452 if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */
454 window = BN_window_bits_for_exponent_size(bits);
457 if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */
461 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
462 !BN_mod_mul_montgomery(val[i],val[i-1],
468 start=1; /* This is used to avoid multiplication etc
469 * when there is only the value '1' in the
471 wvalue=0; /* The 'value' of the window */
472 wstart=bits-1; /* The top bit of the window */
473 wend=0; /* The bottom bit of the window */
475 #if 1 /* by Shay Gueron's suggestion */
476 j = mont->N.top; /* borrow j */
477 if (bn_wexpand(r,j) == NULL) goto err;
478 r->d[0] = (0-m->d[0])&BN_MASK2; /* 2^(top*BN_BITS2) - m */
479 for(i=1;i<j;i++) r->d[i] = (~m->d[i])&BN_MASK2;
482 if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
486 if (BN_is_bit_set(p,wstart) == 0)
490 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
493 if (wstart == 0) break;
497 /* We now have wstart on a 'set' bit, we now need to work out
498 * how bit a window to do. To do this we need to scan
499 * forward until the last set bit before the end of the
504 for (i=1; i<window; i++)
506 if (wstart-i < 0) break;
507 if (BN_is_bit_set(p,wstart-i))
515 /* wend is the size of the current window */
517 /* add the 'bytes above' */
521 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
525 /* wvalue will be an odd number < 2^window */
526 if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx))
529 /* move the 'window' down further */
533 if (wstart < 0) break;
535 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
536 if (OPENSSL_sparcv9cap_P[0]&(SPARCV9_VIS3|SPARCV9_PREFER_FPU))
538 j = mont->N.top; /* borrow j */
539 val[0]->d[0] = 1; /* borrow val[0] */
540 for (i=1;i<j;i++) val[0]->d[i] = 0;
542 if (!BN_mod_mul_montgomery(rr,r,val[0],mont,ctx)) goto err;
546 if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
549 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
555 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
556 static BN_ULONG bn_get_bits(const BIGNUM *a, int bitpos)
561 wordpos = bitpos/BN_BITS2;
563 if (wordpos>=0 && wordpos < a->top)
565 ret = a->d[wordpos]&BN_MASK2;
569 if (++wordpos < a->top)
570 ret |= a->d[wordpos]<<(BN_BITS2-bitpos);
578 /* BN_mod_exp_mont_consttime() stores the precomputed powers in a specific layout
579 * so that accessing any of these table values shows the same access pattern as far
580 * as cache lines are concerned. The following functions are used to transfer a BIGNUM
581 * from/to that table. */
583 static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top, unsigned char *buf, int idx, int width)
588 top = b->top; /* this works because 'buf' is explicitly zeroed */
589 for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
591 buf[j] = ((unsigned char*)b->d)[i];
597 static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width)
601 if (bn_wexpand(b, top) == NULL)
604 for (i=0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
606 ((unsigned char*)b->d)[i] = buf[j];
614 /* Given a pointer value, compute the next address that is a cache line multiple. */
615 #define MOD_EXP_CTIME_ALIGN(x_) \
616 ((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK))))
618 /* This variant of BN_mod_exp_mont() uses fixed windows and the special
619 * precomputation memory layout to limit data-dependency to a minimum
620 * to protect secret exponents (cf. the hyper-threading timing attacks
621 * pointed out by Colin Percival,
622 * http://www.daemonology.net/hyperthreading-considered-harmful/)
624 int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
625 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
627 int i,bits,ret=0,window,wvalue;
629 BN_MONT_CTX *mont=NULL;
632 unsigned char *powerbufFree=NULL;
634 unsigned char *powerbuf=NULL;
636 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
648 BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME,BN_R_CALLED_WITH_EVEN_MODULUS);
660 /* Allocate a montgomery context if it was not supplied by the caller.
661 * If this is not done, things will break in the montgomery part.
667 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
668 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
671 /* Get the window size to use with size of p. */
672 window = BN_window_bits_for_ctime_exponent_size(bits);
673 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
674 if (window>=5 && (top&15)==0 && top<=64 &&
675 (OPENSSL_sparcv9cap_P[1]&(CFR_MONTMUL|CFR_MONTSQR))==
676 (CFR_MONTMUL|CFR_MONTSQR) &&
677 (t4=OPENSSL_sparcv9cap_P[0]))
681 #if defined(OPENSSL_BN_ASM_MONT5)
682 if (window==6 && bits<=1024) window=5; /* ~5% improvement of 2048-bit RSA sign */
686 /* Allocate a buffer large enough to hold all of the pre-computed
687 * powers of am, am itself and tmp.
689 numPowers = 1 << window;
690 powerbufLen = sizeof(m->d[0])*(top*numPowers +
691 ((2*top)>numPowers?(2*top):numPowers));
693 if (powerbufLen < 3072)
694 powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
697 if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
700 powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
701 memset(powerbuf, 0, powerbufLen);
704 if (powerbufLen < 3072)
708 /* lay down tmp and am right after powers table */
709 tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
711 tmp.top = am.top = 0;
712 tmp.dmax = am.dmax = top;
713 tmp.neg = am.neg = 0;
714 tmp.flags = am.flags = BN_FLG_STATIC_DATA;
716 /* prepare a^0 in Montgomery domain */
717 #if 1 /* by Shay Gueron's suggestion */
718 tmp.d[0] = (0-m->d[0])&BN_MASK2; /* 2^(top*BN_BITS2) - m */
720 tmp.d[i] = (~m->d[i])&BN_MASK2;
723 if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx)) goto err;
726 /* prepare a^1 in Montgomery domain */
727 if (a->neg || BN_ucmp(a,m) >= 0)
729 if (!BN_mod(&am,a,m,ctx)) goto err;
730 if (!BN_to_montgomery(&am,&am,mont,ctx)) goto err;
732 else if (!BN_to_montgomery(&am,a,mont,ctx)) goto err;
734 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
737 typedef int (*bn_pwr5_mont_f)(BN_ULONG *tp,const BN_ULONG *np,
738 const BN_ULONG *n0,const void *table,int power,int bits);
739 int bn_pwr5_mont_t4_8(BN_ULONG *tp,const BN_ULONG *np,
740 const BN_ULONG *n0,const void *table,int power,int bits);
741 int bn_pwr5_mont_t4_16(BN_ULONG *tp,const BN_ULONG *np,
742 const BN_ULONG *n0,const void *table,int power,int bits);
743 int bn_pwr5_mont_t4_24(BN_ULONG *tp,const BN_ULONG *np,
744 const BN_ULONG *n0,const void *table,int power,int bits);
745 int bn_pwr5_mont_t4_32(BN_ULONG *tp,const BN_ULONG *np,
746 const BN_ULONG *n0,const void *table,int power,int bits);
747 static const bn_pwr5_mont_f pwr5_funcs[4] = {
748 bn_pwr5_mont_t4_8, bn_pwr5_mont_t4_16,
749 bn_pwr5_mont_t4_24, bn_pwr5_mont_t4_32 };
750 bn_pwr5_mont_f pwr5_worker = pwr5_funcs[top/16-1];
752 typedef int (*bn_mul_mont_f)(BN_ULONG *rp,const BN_ULONG *ap,
753 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
754 int bn_mul_mont_t4_8(BN_ULONG *rp,const BN_ULONG *ap,
755 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
756 int bn_mul_mont_t4_16(BN_ULONG *rp,const BN_ULONG *ap,
757 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
758 int bn_mul_mont_t4_24(BN_ULONG *rp,const BN_ULONG *ap,
759 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
760 int bn_mul_mont_t4_32(BN_ULONG *rp,const BN_ULONG *ap,
761 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
762 static const bn_mul_mont_f mul_funcs[4] = {
763 bn_mul_mont_t4_8, bn_mul_mont_t4_16,
764 bn_mul_mont_t4_24, bn_mul_mont_t4_32 };
765 bn_mul_mont_f mul_worker = mul_funcs[top/16-1];
767 void bn_mul_mont_vis3(BN_ULONG *rp,const BN_ULONG *ap,
768 const void *bp,const BN_ULONG *np,
769 const BN_ULONG *n0,int num);
770 void bn_mul_mont_t4(BN_ULONG *rp,const BN_ULONG *ap,
771 const void *bp,const BN_ULONG *np,
772 const BN_ULONG *n0,int num);
773 void bn_mul_mont_gather5_t4(BN_ULONG *rp,const BN_ULONG *ap,
774 const void *table,const BN_ULONG *np,
775 const BN_ULONG *n0,int num,int power);
776 void bn_flip_n_scatter5_t4(const BN_ULONG *inp,size_t num,
777 void *table,size_t power);
778 void bn_gather5_t4(BN_ULONG *out,size_t num,
779 void *table,size_t power);
780 void bn_flip_t4(BN_ULONG *dst,BN_ULONG *src,size_t num);
782 BN_ULONG *np=mont->N.d, *n0=mont->n0;
783 int stride = 5*(6-(top/16-1)); /* multiple of 5, but less than 32 */
785 /* BN_to_montgomery can contaminate words above .top
786 * [in BN_DEBUG[_DEBUG] build]... */
787 for (i=am.top; i<top; i++) am.d[i]=0;
788 for (i=tmp.top; i<top; i++) tmp.d[i]=0;
790 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,0);
791 bn_flip_n_scatter5_t4(am.d,top,powerbuf,1);
792 if (!(*mul_worker)(tmp.d,am.d,am.d,np,n0) &&
793 !(*mul_worker)(tmp.d,am.d,am.d,np,n0))
794 bn_mul_mont_vis3(tmp.d,am.d,am.d,np,n0,top);
795 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,2);
799 /* Calculate a^i = a^(i-1) * a */
800 if (!(*mul_worker)(tmp.d,tmp.d,am.d,np,n0) &&
801 !(*mul_worker)(tmp.d,tmp.d,am.d,np,n0))
802 bn_mul_mont_vis3(tmp.d,tmp.d,am.d,np,n0,top);
803 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,i);
806 /* switch to 64-bit domain */
807 np = alloca(top*sizeof(BN_ULONG));
809 bn_flip_t4(np,mont->N.d,top);
812 for (wvalue=0, i=bits%5; i>=0; i--,bits--)
813 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
814 bn_gather5_t4(tmp.d,top,powerbuf,wvalue);
816 /* Scan the exponent one window at a time starting from the most
821 if (bits < stride) stride = bits+1;
823 wvalue = bn_get_bits(p,bits+1);
825 if ((*pwr5_worker)(tmp.d,np,n0,powerbuf,wvalue,stride)) continue;
826 /* retry once and fall back */
827 if ((*pwr5_worker)(tmp.d,np,n0,powerbuf,wvalue,stride)) continue;
832 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
833 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
834 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
835 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
836 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
837 bn_mul_mont_gather5_t4(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
840 bn_flip_t4(tmp.d,tmp.d,top);
842 /* back to 32-bit domain */
844 bn_correct_top(&tmp);
845 OPENSSL_cleanse(np,top*sizeof(BN_ULONG));
849 #if defined(OPENSSL_BN_ASM_MONT5)
850 /* This optimization uses ideas from http://eprint.iacr.org/2011/239,
851 * specifically optimization of cache-timing attack countermeasures
852 * and pre-computation optimization. */
854 /* Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as
855 * 512-bit RSA is hardly relevant, we omit it to spare size... */
858 void bn_mul_mont_gather5(BN_ULONG *rp,const BN_ULONG *ap,
859 const void *table,const BN_ULONG *np,
860 const BN_ULONG *n0,int num,int power);
861 void bn_scatter5(const BN_ULONG *inp,size_t num,
862 void *table,size_t power);
863 void bn_gather5(BN_ULONG *out,size_t num,
864 void *table,size_t power);
866 BN_ULONG *np=mont->N.d, *n0=mont->n0;
868 /* BN_to_montgomery can contaminate words above .top
869 * [in BN_DEBUG[_DEBUG] build]... */
870 for (i=am.top; i<top; i++) am.d[i]=0;
871 for (i=tmp.top; i<top; i++) tmp.d[i]=0;
873 bn_scatter5(tmp.d,top,powerbuf,0);
874 bn_scatter5(am.d,am.top,powerbuf,1);
875 bn_mul_mont(tmp.d,am.d,am.d,np,n0,top);
876 bn_scatter5(tmp.d,top,powerbuf,2);
881 /* Calculate a^i = a^(i-1) * a */
882 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
883 bn_scatter5(tmp.d,top,powerbuf,i);
886 /* same as above, but uses squaring for 1/2 of operations */
887 for (i=4; i<32; i*=2)
889 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
890 bn_scatter5(tmp.d,top,powerbuf,i);
895 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
896 bn_scatter5(tmp.d,top,powerbuf,i);
897 for (j=2*i; j<32; j*=2)
899 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
900 bn_scatter5(tmp.d,top,powerbuf,j);
905 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
906 bn_scatter5(tmp.d,top,powerbuf,i);
907 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
908 bn_scatter5(tmp.d,top,powerbuf,2*i);
912 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
913 bn_scatter5(tmp.d,top,powerbuf,i);
917 for (wvalue=0, i=bits%5; i>=0; i--,bits--)
918 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
919 bn_gather5(tmp.d,top,powerbuf,wvalue);
921 /* Scan the exponent one window at a time starting from the most
926 for (wvalue=0, i=0; i<5; i++,bits--)
927 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
929 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
930 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
931 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
932 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
933 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
934 bn_mul_mont_gather5(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
938 bn_correct_top(&tmp);
943 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, numPowers)) goto err;
944 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, numPowers)) goto err;
946 /* If the window size is greater than 1, then calculate
947 * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)
948 * (even powers could instead be computed as (a^(i/2))^2
949 * to use the slight performance advantage of sqr over mul).
953 if (!BN_mod_mul_montgomery(&tmp,&am,&am,mont,ctx)) goto err;
954 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, numPowers)) goto err;
955 for (i=3; i<numPowers; i++)
957 /* Calculate a^i = a^(i-1) * a */
958 if (!BN_mod_mul_montgomery(&tmp,&am,&tmp,mont,ctx))
960 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, numPowers)) goto err;
965 for (wvalue=0, i=bits%window; i>=0; i--,bits--)
966 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
967 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp,top,powerbuf,wvalue,numPowers)) goto err;
969 /* Scan the exponent one window at a time starting from the most
974 wvalue=0; /* The 'value' of the window */
976 /* Scan the window, squaring the result as we go */
977 for (i=0; i<window; i++,bits--)
979 if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx)) goto err;
980 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
983 /* Fetch the appropriate pre-computed value from the pre-buf */
984 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue, numPowers)) goto err;
986 /* Multiply the result into the intermediate result */
987 if (!BN_mod_mul_montgomery(&tmp,&tmp,&am,mont,ctx)) goto err;
991 /* Convert the final result from montgomery to standard format */
992 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
993 if (OPENSSL_sparcv9cap_P[0]&(SPARCV9_VIS3|SPARCV9_PREFER_FPU))
995 am.d[0] = 1; /* borrow am */
996 for (i=1;i<top;i++) am.d[i] = 0;
997 if (!BN_mod_mul_montgomery(rr,&tmp,&am,mont,ctx)) goto err;
1001 if (!BN_from_montgomery(rr,&tmp,mont,ctx)) goto err;
1004 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
1007 OPENSSL_cleanse(powerbuf,powerbufLen);
1008 if (powerbufFree) OPENSSL_free(powerbufFree);
1014 int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
1015 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
1017 BN_MONT_CTX *mont = NULL;
1023 #define BN_MOD_MUL_WORD(r, w, m) \
1024 (BN_mul_word(r, (w)) && \
1025 (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \
1026 (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))
1027 /* BN_MOD_MUL_WORD is only used with 'w' large,
1028 * so the BN_ucmp test is probably more overhead
1029 * than always using BN_mod (which uses BN_copy if
1030 * a similar test returns true). */
1031 /* We can use BN_mod and do not need BN_nnmod because our
1032 * accumulator is never negative (the result of BN_mod does
1033 * not depend on the sign of the modulus).
1035 #define BN_TO_MONTGOMERY_WORD(r, w, mont) \
1036 (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))
1038 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
1040 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1041 BNerr(BN_F_BN_MOD_EXP_MONT_WORD,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
1050 BNerr(BN_F_BN_MOD_EXP_MONT_WORD,BN_R_CALLED_WITH_EVEN_MODULUS);
1054 a %= m->d[0]; /* make sure that 'a' is reduced */
1056 bits = BN_num_bits(p);
1070 d = BN_CTX_get(ctx);
1071 r = BN_CTX_get(ctx);
1072 t = BN_CTX_get(ctx);
1073 if (d == NULL || r == NULL || t == NULL) goto err;
1075 if (in_mont != NULL)
1079 if ((mont = BN_MONT_CTX_new()) == NULL) goto err;
1080 if (!BN_MONT_CTX_set(mont, m, ctx)) goto err;
1083 r_is_one = 1; /* except for Montgomery factor */
1087 /* The result is accumulated in the product r*w. */
1088 w = a; /* bit 'bits-1' of 'p' is always set */
1089 for (b = bits-2; b >= 0; b--)
1091 /* First, square r*w. */
1093 if ((next_w/w) != w) /* overflow */
1097 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1102 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1109 if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) goto err;
1112 /* Second, multiply r*w by 'a' if exponent bit is set. */
1113 if (BN_is_bit_set(p, b))
1116 if ((next_w/a) != w) /* overflow */
1120 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1125 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1133 /* Finally, set r:=r*w. */
1138 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1143 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1147 if (r_is_one) /* can happen only if a == 1*/
1149 if (!BN_one(rr)) goto err;
1153 if (!BN_from_montgomery(rr, r, mont, ctx)) goto err;
1157 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
1164 /* The old fallback, simple version :-) */
1165 int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
1166 const BIGNUM *m, BN_CTX *ctx)
1168 int i,j,bits,ret=0,wstart,wend,window,wvalue;
1171 /* Table of variables obtained from 'ctx' */
1172 BIGNUM *val[TABLE_SIZE];
1174 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
1176 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1177 BNerr(BN_F_BN_MOD_EXP_SIMPLE,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
1181 bits=BN_num_bits(p);
1190 d = BN_CTX_get(ctx);
1191 val[0] = BN_CTX_get(ctx);
1192 if(!d || !val[0]) goto err;
1194 if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */
1195 if (BN_is_zero(val[0]))
1202 window = BN_window_bits_for_exponent_size(bits);
1205 if (!BN_mod_mul(d,val[0],val[0],m,ctx))
1210 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
1211 !BN_mod_mul(val[i],val[i-1],d,m,ctx))
1216 start=1; /* This is used to avoid multiplication etc
1217 * when there is only the value '1' in the
1219 wvalue=0; /* The 'value' of the window */
1220 wstart=bits-1; /* The top bit of the window */
1221 wend=0; /* The bottom bit of the window */
1223 if (!BN_one(r)) goto err;
1227 if (BN_is_bit_set(p,wstart) == 0)
1230 if (!BN_mod_mul(r,r,r,m,ctx))
1232 if (wstart == 0) break;
1236 /* We now have wstart on a 'set' bit, we now need to work out
1237 * how bit a window to do. To do this we need to scan
1238 * forward until the last set bit before the end of the
1243 for (i=1; i<window; i++)
1245 if (wstart-i < 0) break;
1246 if (BN_is_bit_set(p,wstart-i))
1254 /* wend is the size of the current window */
1256 /* add the 'bytes above' */
1260 if (!BN_mod_mul(r,r,r,m,ctx))
1264 /* wvalue will be an odd number < 2^window */
1265 if (!BN_mod_mul(r,r,val[wvalue>>1],m,ctx))
1268 /* move the 'window' down further */
1272 if (wstart < 0) break;