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))
131 #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc))
132 # include "sparc_arch.h"
133 extern unsigned int OPENSSL_sparcv9cap_P[];
134 # define SPARC_T4_MONT
137 /* maximum precomputation table size for *variable* sliding windows */
138 #define TABLE_SIZE 32
140 /* this one works - simple but works */
141 int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
146 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
148 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
149 BNerr(BN_F_BN_EXP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
154 if ((r == a) || (r == p))
155 rr = BN_CTX_get(ctx);
159 if (rr == NULL || v == NULL) goto err;
161 if (BN_copy(v,a) == NULL) goto err;
165 { if (BN_copy(rr,a) == NULL) goto err; }
166 else { if (!BN_one(rr)) goto err; }
168 for (i=1; i<bits; i++)
170 if (!BN_sqr(v,v,ctx)) goto err;
171 if (BN_is_bit_set(p,i))
173 if (!BN_mul(rr,rr,v,ctx)) goto err;
178 if (r != rr) BN_copy(r,rr);
185 int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
194 /* For even modulus m = 2^k*m_odd, it might make sense to compute
195 * a^p mod m_odd and a^p mod 2^k separately (with Montgomery
196 * exponentiation for the odd part), using appropriate exponent
197 * reductions, and combine the results using the CRT.
199 * For now, we use Montgomery only if the modulus is odd; otherwise,
200 * exponentiation using the reciprocal-based quick remaindering
203 * (Timing obtained with expspeed.c [computations a^p mod m
204 * where a, p, m are of the same length: 256, 512, 1024, 2048,
205 * 4096, 8192 bits], compared to the running time of the
206 * standard algorithm:
208 * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration]
209 * 55 .. 77 % [UltraSparc processor, but
210 * debug-solaris-sparcv8-gcc conf.]
212 * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration]
213 * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc]
215 * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont
216 * at 2048 and more bits, but at 512 and 1024 bits, it was
217 * slower even than the standard algorithm!
219 * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations]
220 * should be obtained when the new Montgomery reduction code
221 * has been integrated into OpenSSL.)
225 #define MONT_EXP_WORD
229 /* I have finally been able to take out this pre-condition of
230 * the top bit being set. It was caused by an error in BN_div
231 * with negatives. There was also another problem when for a^b%m
232 * a >= m. eay 07-May-97 */
233 /* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */
237 # ifdef MONT_EXP_WORD
238 if (a->top == 1 && !a->neg && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0))
240 BN_ULONG A = a->d[0];
241 ret=BN_mod_exp_mont_word(r,A,p,m,ctx,NULL);
245 ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL);
250 { ret=BN_mod_exp_recp(r,a,p,m,ctx); }
252 { ret=BN_mod_exp_simple(r,a,p,m,ctx); }
260 int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
261 const BIGNUM *m, BN_CTX *ctx)
263 int i,j,bits,ret=0,wstart,wend,window,wvalue;
266 /* Table of variables obtained from 'ctx' */
267 BIGNUM *val[TABLE_SIZE];
270 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
272 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
273 BNerr(BN_F_BN_MOD_EXP_RECP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
286 aa = BN_CTX_get(ctx);
287 val[0] = BN_CTX_get(ctx);
288 if(!aa || !val[0]) goto err;
290 BN_RECP_CTX_init(&recp);
293 /* ignore sign of 'm' */
294 if (!BN_copy(aa, m)) goto err;
296 if (BN_RECP_CTX_set(&recp,aa,ctx) <= 0) goto err;
300 if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;
303 if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */
304 if (BN_is_zero(val[0]))
311 window = BN_window_bits_for_exponent_size(bits);
314 if (!BN_mod_mul_reciprocal(aa,val[0],val[0],&recp,ctx))
319 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
320 !BN_mod_mul_reciprocal(val[i],val[i-1],
326 start=1; /* This is used to avoid multiplication etc
327 * when there is only the value '1' in the
329 wvalue=0; /* The 'value' of the window */
330 wstart=bits-1; /* The top bit of the window */
331 wend=0; /* The bottom bit of the window */
333 if (!BN_one(r)) goto err;
337 if (BN_is_bit_set(p,wstart) == 0)
340 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
342 if (wstart == 0) break;
346 /* We now have wstart on a 'set' bit, we now need to work out
347 * how bit a window to do. To do this we need to scan
348 * forward until the last set bit before the end of the
353 for (i=1; i<window; i++)
355 if (wstart-i < 0) break;
356 if (BN_is_bit_set(p,wstart-i))
364 /* wend is the size of the current window */
366 /* add the 'bytes above' */
370 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
374 /* wvalue will be an odd number < 2^window */
375 if (!BN_mod_mul_reciprocal(r,r,val[wvalue>>1],&recp,ctx))
378 /* move the 'window' down further */
382 if (wstart < 0) break;
387 BN_RECP_CTX_free(&recp);
393 int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
394 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
396 int i,j,bits,ret=0,wstart,wend,window,wvalue;
400 /* Table of variables obtained from 'ctx' */
401 BIGNUM *val[TABLE_SIZE];
402 BN_MONT_CTX *mont=NULL;
404 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
406 return BN_mod_exp_mont_consttime(rr, a, p, m, ctx, in_mont);
415 BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
428 val[0] = BN_CTX_get(ctx);
429 if (!d || !r || !val[0]) goto err;
431 /* If this is not done, things will break in the montgomery
438 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
439 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
442 if (a->neg || BN_ucmp(a,m) >= 0)
444 if (!BN_nnmod(val[0],a,m,ctx))
456 if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */
458 window = BN_window_bits_for_exponent_size(bits);
461 if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */
465 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
466 !BN_mod_mul_montgomery(val[i],val[i-1],
472 start=1; /* This is used to avoid multiplication etc
473 * when there is only the value '1' in the
475 wvalue=0; /* The 'value' of the window */
476 wstart=bits-1; /* The top bit of the window */
477 wend=0; /* The bottom bit of the window */
479 #if 1 /* by Shay Gueron's suggestion */
480 j = m->top; /* borrow j */
481 if (m->d[j-1] & (((BN_ULONG)1)<<(BN_BITS2-1)))
483 if (bn_wexpand(r,j) == NULL) goto err;
484 /* 2^(top*BN_BITS2) - m */
485 r->d[0] = (0-m->d[0])&BN_MASK2;
486 for(i=1;i<j;i++) r->d[i] = (~m->d[i])&BN_MASK2;
491 if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
494 if (BN_is_bit_set(p,wstart) == 0)
498 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
501 if (wstart == 0) break;
505 /* We now have wstart on a 'set' bit, we now need to work out
506 * how bit a window to do. To do this we need to scan
507 * forward until the last set bit before the end of the
512 for (i=1; i<window; i++)
514 if (wstart-i < 0) break;
515 if (BN_is_bit_set(p,wstart-i))
523 /* wend is the size of the current window */
525 /* add the 'bytes above' */
529 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
533 /* wvalue will be an odd number < 2^window */
534 if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx))
537 /* move the 'window' down further */
541 if (wstart < 0) break;
543 #if defined(SPARC_T4_MONT)
544 if (OPENSSL_sparcv9cap_P[0]&(SPARCV9_VIS3|SPARCV9_PREFER_FPU))
546 j = mont->N.top; /* borrow j */
547 val[0]->d[0] = 1; /* borrow val[0] */
548 for (i=1;i<j;i++) val[0]->d[i] = 0;
550 if (!BN_mod_mul_montgomery(rr,r,val[0],mont,ctx)) goto err;
554 if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
557 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
563 #if defined(SPARC_T4_MONT)
564 static BN_ULONG bn_get_bits(const BIGNUM *a, int bitpos)
569 wordpos = bitpos/BN_BITS2;
571 if (wordpos>=0 && wordpos < a->top)
573 ret = a->d[wordpos]&BN_MASK2;
577 if (++wordpos < a->top)
578 ret |= a->d[wordpos]<<(BN_BITS2-bitpos);
586 /* BN_mod_exp_mont_consttime() stores the precomputed powers in a specific layout
587 * so that accessing any of these table values shows the same access pattern as far
588 * as cache lines are concerned. The following functions are used to transfer a BIGNUM
589 * from/to that table. */
591 static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top, unsigned char *buf, int idx, int width)
596 top = b->top; /* this works because 'buf' is explicitly zeroed */
597 for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
599 buf[j] = ((unsigned char*)b->d)[i];
605 static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width)
609 if (bn_wexpand(b, top) == NULL)
612 for (i=0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
614 ((unsigned char*)b->d)[i] = buf[j];
622 /* Given a pointer value, compute the next address that is a cache line multiple. */
623 #define MOD_EXP_CTIME_ALIGN(x_) \
624 ((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK))))
626 /* This variant of BN_mod_exp_mont() uses fixed windows and the special
627 * precomputation memory layout to limit data-dependency to a minimum
628 * to protect secret exponents (cf. the hyper-threading timing attacks
629 * pointed out by Colin Percival,
630 * http://www.daemonology.net/hyperthreading-considered-harmful/)
632 int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
633 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
635 int i,bits,ret=0,window,wvalue;
637 BN_MONT_CTX *mont=NULL;
640 unsigned char *powerbufFree=NULL;
642 unsigned char *powerbuf=NULL;
644 #if defined(SPARC_T4_MONT)
656 BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME,BN_R_CALLED_WITH_EVEN_MODULUS);
668 /* Allocate a montgomery context if it was not supplied by the caller.
669 * If this is not done, things will break in the montgomery part.
675 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
676 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
679 /* Get the window size to use with size of p. */
680 window = BN_window_bits_for_ctime_exponent_size(bits);
681 #if defined(SPARC_T4_MONT)
682 if (window>=5 && (top&15)==0 && top<=64 &&
683 (OPENSSL_sparcv9cap_P[1]&(CFR_MONTMUL|CFR_MONTSQR))==
684 (CFR_MONTMUL|CFR_MONTSQR) &&
685 (t4=OPENSSL_sparcv9cap_P[0]))
689 #if defined(OPENSSL_BN_ASM_MONT5)
690 if (window==6 && bits<=1024) window=5; /* ~5% improvement of 2048-bit RSA sign */
694 /* Allocate a buffer large enough to hold all of the pre-computed
695 * powers of am, am itself and tmp.
697 numPowers = 1 << window;
698 powerbufLen = sizeof(m->d[0])*(top*numPowers +
699 ((2*top)>numPowers?(2*top):numPowers));
701 if (powerbufLen < 3072)
702 powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
705 if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
708 powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
709 memset(powerbuf, 0, powerbufLen);
712 if (powerbufLen < 3072)
716 /* lay down tmp and am right after powers table */
717 tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
719 tmp.top = am.top = 0;
720 tmp.dmax = am.dmax = top;
721 tmp.neg = am.neg = 0;
722 tmp.flags = am.flags = BN_FLG_STATIC_DATA;
724 /* prepare a^0 in Montgomery domain */
725 #if 1 /* by Shay Gueron's suggestion */
726 if (m->d[top-1] & (((BN_ULONG)1)<<(BN_BITS2-1)))
728 /* 2^(top*BN_BITS2) - m */
729 tmp.d[0] = (0-m->d[0])&BN_MASK2;
730 for (i=1;i<top;i++) tmp.d[i] = (~m->d[i])&BN_MASK2;
735 if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx)) goto err;
737 /* prepare a^1 in Montgomery domain */
738 if (a->neg || BN_ucmp(a,m) >= 0)
740 if (!BN_mod(&am,a,m,ctx)) goto err;
741 if (!BN_to_montgomery(&am,&am,mont,ctx)) goto err;
743 else if (!BN_to_montgomery(&am,a,mont,ctx)) goto err;
745 #if defined(SPARC_T4_MONT)
748 typedef int (*bn_pwr5_mont_f)(BN_ULONG *tp,const BN_ULONG *np,
749 const BN_ULONG *n0,const void *table,int power,int bits);
750 int bn_pwr5_mont_t4_8(BN_ULONG *tp,const BN_ULONG *np,
751 const BN_ULONG *n0,const void *table,int power,int bits);
752 int bn_pwr5_mont_t4_16(BN_ULONG *tp,const BN_ULONG *np,
753 const BN_ULONG *n0,const void *table,int power,int bits);
754 int bn_pwr5_mont_t4_24(BN_ULONG *tp,const BN_ULONG *np,
755 const BN_ULONG *n0,const void *table,int power,int bits);
756 int bn_pwr5_mont_t4_32(BN_ULONG *tp,const BN_ULONG *np,
757 const BN_ULONG *n0,const void *table,int power,int bits);
758 static const bn_pwr5_mont_f pwr5_funcs[4] = {
759 bn_pwr5_mont_t4_8, bn_pwr5_mont_t4_16,
760 bn_pwr5_mont_t4_24, bn_pwr5_mont_t4_32 };
761 bn_pwr5_mont_f pwr5_worker = pwr5_funcs[top/16-1];
763 typedef int (*bn_mul_mont_f)(BN_ULONG *rp,const BN_ULONG *ap,
764 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
765 int bn_mul_mont_t4_8(BN_ULONG *rp,const BN_ULONG *ap,
766 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
767 int bn_mul_mont_t4_16(BN_ULONG *rp,const BN_ULONG *ap,
768 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
769 int bn_mul_mont_t4_24(BN_ULONG *rp,const BN_ULONG *ap,
770 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
771 int bn_mul_mont_t4_32(BN_ULONG *rp,const BN_ULONG *ap,
772 const void *bp,const BN_ULONG *np,const BN_ULONG *n0);
773 static const bn_mul_mont_f mul_funcs[4] = {
774 bn_mul_mont_t4_8, bn_mul_mont_t4_16,
775 bn_mul_mont_t4_24, bn_mul_mont_t4_32 };
776 bn_mul_mont_f mul_worker = mul_funcs[top/16-1];
778 void bn_mul_mont_vis3(BN_ULONG *rp,const BN_ULONG *ap,
779 const void *bp,const BN_ULONG *np,
780 const BN_ULONG *n0,int num);
781 void bn_mul_mont_t4(BN_ULONG *rp,const BN_ULONG *ap,
782 const void *bp,const BN_ULONG *np,
783 const BN_ULONG *n0,int num);
784 void bn_mul_mont_gather5_t4(BN_ULONG *rp,const BN_ULONG *ap,
785 const void *table,const BN_ULONG *np,
786 const BN_ULONG *n0,int num,int power);
787 void bn_flip_n_scatter5_t4(const BN_ULONG *inp,size_t num,
788 void *table,size_t power);
789 void bn_gather5_t4(BN_ULONG *out,size_t num,
790 void *table,size_t power);
791 void bn_flip_t4(BN_ULONG *dst,BN_ULONG *src,size_t num);
793 BN_ULONG *np=mont->N.d, *n0=mont->n0;
794 int stride = 5*(6-(top/16-1)); /* multiple of 5, but less than 32 */
796 /* BN_to_montgomery can contaminate words above .top
797 * [in BN_DEBUG[_DEBUG] build]... */
798 for (i=am.top; i<top; i++) am.d[i]=0;
799 for (i=tmp.top; i<top; i++) tmp.d[i]=0;
801 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,0);
802 bn_flip_n_scatter5_t4(am.d,top,powerbuf,1);
803 if (!(*mul_worker)(tmp.d,am.d,am.d,np,n0) &&
804 !(*mul_worker)(tmp.d,am.d,am.d,np,n0))
805 bn_mul_mont_vis3(tmp.d,am.d,am.d,np,n0,top);
806 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,2);
810 /* Calculate a^i = a^(i-1) * a */
811 if (!(*mul_worker)(tmp.d,tmp.d,am.d,np,n0) &&
812 !(*mul_worker)(tmp.d,tmp.d,am.d,np,n0))
813 bn_mul_mont_vis3(tmp.d,tmp.d,am.d,np,n0,top);
814 bn_flip_n_scatter5_t4(tmp.d,top,powerbuf,i);
817 /* switch to 64-bit domain */
818 np = alloca(top*sizeof(BN_ULONG));
820 bn_flip_t4(np,mont->N.d,top);
823 for (wvalue=0, i=bits%5; i>=0; i--,bits--)
824 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
825 bn_gather5_t4(tmp.d,top,powerbuf,wvalue);
827 /* Scan the exponent one window at a time starting from the most
832 if (bits < stride) stride = bits+1;
834 wvalue = bn_get_bits(p,bits+1);
836 if ((*pwr5_worker)(tmp.d,np,n0,powerbuf,wvalue,stride)) continue;
837 /* retry once and fall back */
838 if ((*pwr5_worker)(tmp.d,np,n0,powerbuf,wvalue,stride)) continue;
843 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
844 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
845 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
846 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
847 bn_mul_mont_t4(tmp.d,tmp.d,tmp.d,np,n0,top);
848 bn_mul_mont_gather5_t4(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
851 bn_flip_t4(tmp.d,tmp.d,top);
853 /* back to 32-bit domain */
855 bn_correct_top(&tmp);
856 OPENSSL_cleanse(np,top*sizeof(BN_ULONG));
860 #if defined(OPENSSL_BN_ASM_MONT5)
861 /* This optimization uses ideas from http://eprint.iacr.org/2011/239,
862 * specifically optimization of cache-timing attack countermeasures
863 * and pre-computation optimization. */
865 /* Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as
866 * 512-bit RSA is hardly relevant, we omit it to spare size... */
869 void bn_mul_mont_gather5(BN_ULONG *rp,const BN_ULONG *ap,
870 const void *table,const BN_ULONG *np,
871 const BN_ULONG *n0,int num,int power);
872 void bn_scatter5(const BN_ULONG *inp,size_t num,
873 void *table,size_t power);
874 void bn_gather5(BN_ULONG *out,size_t num,
875 void *table,size_t power);
877 BN_ULONG *np=mont->N.d, *n0=mont->n0;
879 /* BN_to_montgomery can contaminate words above .top
880 * [in BN_DEBUG[_DEBUG] build]... */
881 for (i=am.top; i<top; i++) am.d[i]=0;
882 for (i=tmp.top; i<top; i++) tmp.d[i]=0;
884 bn_scatter5(tmp.d,top,powerbuf,0);
885 bn_scatter5(am.d,am.top,powerbuf,1);
886 bn_mul_mont(tmp.d,am.d,am.d,np,n0,top);
887 bn_scatter5(tmp.d,top,powerbuf,2);
892 /* Calculate a^i = a^(i-1) * a */
893 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
894 bn_scatter5(tmp.d,top,powerbuf,i);
897 /* same as above, but uses squaring for 1/2 of operations */
898 for (i=4; i<32; i*=2)
900 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
901 bn_scatter5(tmp.d,top,powerbuf,i);
906 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
907 bn_scatter5(tmp.d,top,powerbuf,i);
908 for (j=2*i; j<32; j*=2)
910 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
911 bn_scatter5(tmp.d,top,powerbuf,j);
916 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
917 bn_scatter5(tmp.d,top,powerbuf,i);
918 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
919 bn_scatter5(tmp.d,top,powerbuf,2*i);
923 bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
924 bn_scatter5(tmp.d,top,powerbuf,i);
928 for (wvalue=0, i=bits%5; i>=0; i--,bits--)
929 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
930 bn_gather5(tmp.d,top,powerbuf,wvalue);
932 /* Scan the exponent one window at a time starting from the most
937 for (wvalue=0, i=0; i<5; i++,bits--)
938 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
940 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
941 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
942 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
943 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
944 bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
945 bn_mul_mont_gather5(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
949 bn_correct_top(&tmp);
954 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, numPowers)) goto err;
955 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, numPowers)) goto err;
957 /* If the window size is greater than 1, then calculate
958 * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)
959 * (even powers could instead be computed as (a^(i/2))^2
960 * to use the slight performance advantage of sqr over mul).
964 if (!BN_mod_mul_montgomery(&tmp,&am,&am,mont,ctx)) goto err;
965 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, numPowers)) goto err;
966 for (i=3; i<numPowers; i++)
968 /* Calculate a^i = a^(i-1) * a */
969 if (!BN_mod_mul_montgomery(&tmp,&am,&tmp,mont,ctx))
971 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, numPowers)) goto err;
976 for (wvalue=0, i=bits%window; i>=0; i--,bits--)
977 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
978 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp,top,powerbuf,wvalue,numPowers)) goto err;
980 /* Scan the exponent one window at a time starting from the most
985 wvalue=0; /* The 'value' of the window */
987 /* Scan the window, squaring the result as we go */
988 for (i=0; i<window; i++,bits--)
990 if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx)) goto err;
991 wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
994 /* Fetch the appropriate pre-computed value from the pre-buf */
995 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue, numPowers)) goto err;
997 /* Multiply the result into the intermediate result */
998 if (!BN_mod_mul_montgomery(&tmp,&tmp,&am,mont,ctx)) goto err;
1002 /* Convert the final result from montgomery to standard format */
1003 #if defined(SPARC_T4_MONT)
1004 if (OPENSSL_sparcv9cap_P[0]&(SPARCV9_VIS3|SPARCV9_PREFER_FPU))
1006 am.d[0] = 1; /* borrow am */
1007 for (i=1;i<top;i++) am.d[i] = 0;
1008 if (!BN_mod_mul_montgomery(rr,&tmp,&am,mont,ctx)) goto err;
1012 if (!BN_from_montgomery(rr,&tmp,mont,ctx)) goto err;
1015 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
1018 OPENSSL_cleanse(powerbuf,powerbufLen);
1019 if (powerbufFree) OPENSSL_free(powerbufFree);
1025 int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
1026 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
1028 BN_MONT_CTX *mont = NULL;
1034 #define BN_MOD_MUL_WORD(r, w, m) \
1035 (BN_mul_word(r, (w)) && \
1036 (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \
1037 (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))
1038 /* BN_MOD_MUL_WORD is only used with 'w' large,
1039 * so the BN_ucmp test is probably more overhead
1040 * than always using BN_mod (which uses BN_copy if
1041 * a similar test returns true). */
1042 /* We can use BN_mod and do not need BN_nnmod because our
1043 * accumulator is never negative (the result of BN_mod does
1044 * not depend on the sign of the modulus).
1046 #define BN_TO_MONTGOMERY_WORD(r, w, mont) \
1047 (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))
1049 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
1051 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1052 BNerr(BN_F_BN_MOD_EXP_MONT_WORD,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
1061 BNerr(BN_F_BN_MOD_EXP_MONT_WORD,BN_R_CALLED_WITH_EVEN_MODULUS);
1065 a %= m->d[0]; /* make sure that 'a' is reduced */
1067 bits = BN_num_bits(p);
1081 d = BN_CTX_get(ctx);
1082 r = BN_CTX_get(ctx);
1083 t = BN_CTX_get(ctx);
1084 if (d == NULL || r == NULL || t == NULL) goto err;
1086 if (in_mont != NULL)
1090 if ((mont = BN_MONT_CTX_new()) == NULL) goto err;
1091 if (!BN_MONT_CTX_set(mont, m, ctx)) goto err;
1094 r_is_one = 1; /* except for Montgomery factor */
1098 /* The result is accumulated in the product r*w. */
1099 w = a; /* bit 'bits-1' of 'p' is always set */
1100 for (b = bits-2; b >= 0; b--)
1102 /* First, square r*w. */
1104 if ((next_w/w) != w) /* overflow */
1108 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1113 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1120 if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) goto err;
1123 /* Second, multiply r*w by 'a' if exponent bit is set. */
1124 if (BN_is_bit_set(p, b))
1127 if ((next_w/a) != w) /* overflow */
1131 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1136 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1144 /* Finally, set r:=r*w. */
1149 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
1154 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
1158 if (r_is_one) /* can happen only if a == 1*/
1160 if (!BN_one(rr)) goto err;
1164 if (!BN_from_montgomery(rr, r, mont, ctx)) goto err;
1168 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
1175 /* The old fallback, simple version :-) */
1176 int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
1177 const BIGNUM *m, BN_CTX *ctx)
1179 int i,j,bits,ret=0,wstart,wend,window,wvalue;
1182 /* Table of variables obtained from 'ctx' */
1183 BIGNUM *val[TABLE_SIZE];
1185 if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)
1187 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1188 BNerr(BN_F_BN_MOD_EXP_SIMPLE,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
1192 bits=BN_num_bits(p);
1201 d = BN_CTX_get(ctx);
1202 val[0] = BN_CTX_get(ctx);
1203 if(!d || !val[0]) goto err;
1205 if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */
1206 if (BN_is_zero(val[0]))
1213 window = BN_window_bits_for_exponent_size(bits);
1216 if (!BN_mod_mul(d,val[0],val[0],m,ctx))
1221 if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
1222 !BN_mod_mul(val[i],val[i-1],d,m,ctx))
1227 start=1; /* This is used to avoid multiplication etc
1228 * when there is only the value '1' in the
1230 wvalue=0; /* The 'value' of the window */
1231 wstart=bits-1; /* The top bit of the window */
1232 wend=0; /* The bottom bit of the window */
1234 if (!BN_one(r)) goto err;
1238 if (BN_is_bit_set(p,wstart) == 0)
1241 if (!BN_mod_mul(r,r,r,m,ctx))
1243 if (wstart == 0) break;
1247 /* We now have wstart on a 'set' bit, we now need to work out
1248 * how bit a window to do. To do this we need to scan
1249 * forward until the last set bit before the end of the
1254 for (i=1; i<window; i++)
1256 if (wstart-i < 0) break;
1257 if (BN_is_bit_set(p,wstart-i))
1265 /* wend is the size of the current window */
1267 /* add the 'bytes above' */
1271 if (!BN_mod_mul(r,r,r,m,ctx))
1275 /* wvalue will be an odd number < 2^window */
1276 if (!BN_mod_mul(r,r,val[wvalue>>1],m,ctx))
1279 /* move the 'window' down further */
1283 if (wstart < 0) break;