openssl/crypto/bn/bn_exp.c - Issue 2072073002: Delete bundled copy of OpenSSL and replace with README.

Unified Diff: openssl/crypto/bn/bn_exp.c

Issue 2072073002: Delete bundled copy of OpenSSL and replace with README. (Closed) Base URL: https://chromium.googlesource.com/chromium/deps/openssl@master

Patch Set: Delete bundled copy of OpenSSL and replace with README. Created 4 years, 6 months ago

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Index: openssl/crypto/bn/bn_exp.c

diff --git a/openssl/crypto/bn/bn_exp.c b/openssl/crypto/bn/bn_exp.c

deleted file mode 100644

index 2abf6fd67871aa43cfbfc12aa6d02cb9e6903efc..0000000000000000000000000000000000000000

--- a/openssl/crypto/bn/bn_exp.c

+++ /dev/null

@@ -1,1097 +0,0 @@

-/* crypto/bn/bn_exp.c */

- *

- * This package is an SSL implementation written

- * by Eric Young (eay@cryptsoft.com).

- * The implementation was written so as to conform with Netscapes SSL.

- *

- * This library is free for commercial and non-commercial use as long as

- * the following conditions are aheared to. The following conditions

- * apply to all code found in this distribution, be it the RC4, RSA,

- * lhash, DES, etc., code; not just the SSL code. The SSL documentation

- * included with this distribution is covered by the same copyright terms

- * except that the holder is Tim Hudson (tjh@cryptsoft.com).

- *

- * Copyright remains Eric Young's, and as such any Copyright notices in

- * the code are not to be removed.

- * If this package is used in a product, Eric Young should be given attribution

- * as the author of the parts of the library used.

- * This can be in the form of a textual message at program startup or

- * in documentation (online or textual) provided with the package.

- *

- * Redistribution and use in source and binary forms, with or without

- * modification, are permitted provided that the following conditions

- * are met:

- * 1. Redistributions of source code must retain the copyright

- * notice, this list of conditions and the following disclaimer.

- * 2. Redistributions in binary form must reproduce the above copyright

- * notice, this list of conditions and the following disclaimer in the

- * documentation and/or other materials provided with the distribution.

- * 3. All advertising materials mentioning features or use of this software

- * must display the following acknowledgement:

- * "This product includes cryptographic software written by

- * Eric Young (eay@cryptsoft.com)"

- * The word 'cryptographic' can be left out if the rouines from the library

- * being used are not cryptographic related :-).

- * 4. If you include any Windows specific code (or a derivative thereof) from

- * the apps directory (application code) you must include an acknowledgement:

- * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

- *

- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

- * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

- * SUCH DAMAGE.

- *

- * The licence and distribution terms for any publically available version or

- * derivative of this code cannot be changed. i.e. this code cannot simply be

- * copied and put under another distribution licence

- * [including the GNU Public Licence.]

- */

-/* ====================================================================

- *

- * Redistribution and use in source and binary forms, with or without

- * modification, are permitted provided that the following conditions

- * are met:

- *

- * 1. Redistributions of source code must retain the above copyright

- * notice, this list of conditions and the following disclaimer.

- *

- * 2. Redistributions in binary form must reproduce the above copyright

- * notice, this list of conditions and the following disclaimer in

- * the documentation and/or other materials provided with the

- * distribution.

- *

- * 3. All advertising materials mentioning features or use of this

- * software must display the following acknowledgment:

- * "This product includes software developed by the OpenSSL Project

- * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

- *

- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

- * endorse or promote products derived from this software without

- * prior written permission. For written permission, please contact

- * openssl-core@openssl.org.

- *

- * 5. Products derived from this software may not be called "OpenSSL"

- * nor may "OpenSSL" appear in their names without prior written

- * permission of the OpenSSL Project.

- *

- * 6. Redistributions of any form whatsoever must retain the following

- * acknowledgment:

- * "This product includes software developed by the OpenSSL Project

- * for use in the OpenSSL Toolkit (http://www.openssl.org/)"

- *

- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR

- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

- * OF THE POSSIBILITY OF SUCH DAMAGE.

- * ====================================================================

- *

- * This product includes cryptographic software written by Eric Young

- * (eay@cryptsoft.com). This product includes software written by Tim

- * Hudson (tjh@cryptsoft.com).

- *

- */

-#include "cryptlib.h"

-#include "bn_lcl.h"

-#include <stdlib.h>

-#ifdef _WIN32

-# include <malloc.h>

-# ifndef alloca

-# define alloca _alloca

-# endif

-#elif defined(__GNUC__)

-# ifndef alloca

-# define alloca(s) __builtin_alloca((s))

-# endif

-#endif

-/* maximum precomputation table size for *variable* sliding windows */

-#define TABLE_SIZE 32

-/* this one works - simple but works */

-int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)

- {

- int i,bits,ret=0;

- BIGNUM *v,*rr;

- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)

- {

- /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */

- BNerr(BN_F_BN_EXP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

- return -1;

- }

- BN_CTX_start(ctx);

- if ((r == a) || (r == p))

- rr = BN_CTX_get(ctx);

- else

- rr = r;

- v = BN_CTX_get(ctx);

- if (rr == NULL || v == NULL) goto err;

- if (BN_copy(v,a) == NULL) goto err;

- bits=BN_num_bits(p);

- if (BN_is_odd(p))

- { if (BN_copy(rr,a) == NULL) goto err; }

- else { if (!BN_one(rr)) goto err; }

- for (i=1; i<bits; i++)

- {

- if (!BN_sqr(v,v,ctx)) goto err;

- if (BN_is_bit_set(p,i))

- {

- if (!BN_mul(rr,rr,v,ctx)) goto err;

- }

- ret=1;

-err:

- if (r != rr) BN_copy(r,rr);

- BN_CTX_end(ctx);

- bn_check_top(r);

- return(ret);

- }

-int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,

- BN_CTX *ctx)

- {

- int ret;

- bn_check_top(a);

- bn_check_top(p);

- bn_check_top(m);

- /* For even modulus m = 2^k*m_odd, it might make sense to compute

- * a^p mod m_odd and a^p mod 2^k separately (with Montgomery

- * exponentiation for the odd part), using appropriate exponent

- * reductions, and combine the results using the CRT.

- *

- * For now, we use Montgomery only if the modulus is odd; otherwise,

- * exponentiation using the reciprocal-based quick remaindering

- * algorithm is used.

- *

- * (Timing obtained with expspeed.c [computations a^p mod m

- * where a, p, m are of the same length: 256, 512, 1024, 2048,

- * 4096, 8192 bits], compared to the running time of the

- * standard algorithm:

- *

- * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration]

- * 55 .. 77 % [UltraSparc processor, but

- * debug-solaris-sparcv8-gcc conf.]

- *

- * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration]

- * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc]

- *

- * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont

- * at 2048 and more bits, but at 512 and 1024 bits, it was

- * slower even than the standard algorithm!

- *

- * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations]

- * should be obtained when the new Montgomery reduction code

- * has been integrated into OpenSSL.)

- */

-#define MONT_MUL_MOD

-#define MONT_EXP_WORD

-#define RECP_MUL_MOD

-#ifdef MONT_MUL_MOD

- /* I have finally been able to take out this pre-condition of

- * the top bit being set. It was caused by an error in BN_div

- * with negatives. There was also another problem when for a^b%m

- * a >= m. eay 07-May-97 */

-/* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */

- if (BN_is_odd(m))

- {

-# ifdef MONT_EXP_WORD

- if (a->top == 1 && !a->neg && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0))

- {

- BN_ULONG A = a->d[0];

- ret=BN_mod_exp_mont_word(r,A,p,m,ctx,NULL);

- }

- else

-# endif

- ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL);

- }

- else

-#endif

-#ifdef RECP_MUL_MOD

- { ret=BN_mod_exp_recp(r,a,p,m,ctx); }

-#else

- { ret=BN_mod_exp_simple(r,a,p,m,ctx); }

-#endif

- bn_check_top(r);

- return(ret);

- }

-int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

- const BIGNUM *m, BN_CTX *ctx)

- {

- int i,j,bits,ret=0,wstart,wend,window,wvalue;

- int start=1;

- BIGNUM *aa;

- /* Table of variables obtained from 'ctx' */

- BIGNUM *val[TABLE_SIZE];

- BN_RECP_CTX recp;

- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)

- {

- /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */

- BNerr(BN_F_BN_MOD_EXP_RECP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

- return -1;

- }

- bits=BN_num_bits(p);

- if (bits == 0)

- {

- ret = BN_one(r);

- return ret;

- }

- BN_CTX_start(ctx);

- aa = BN_CTX_get(ctx);

- val[0] = BN_CTX_get(ctx);

- if(!aa || !val[0]) goto err;

- BN_RECP_CTX_init(&recp);

- if (m->neg)

- {

- /* ignore sign of 'm' */

- if (!BN_copy(aa, m)) goto err;

- aa->neg = 0;

- if (BN_RECP_CTX_set(&recp,aa,ctx) <= 0) goto err;

- }

- else

- {

- if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;

- }

- if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */

- if (BN_is_zero(val[0]))

- {

- BN_zero(r);

- ret = 1;

- goto err;

- }

- window = BN_window_bits_for_exponent_size(bits);

- if (window > 1)

- {

- if (!BN_mod_mul_reciprocal(aa,val[0],val[0],&recp,ctx))

- goto err; /* 2 */

- j=1<<(window-1);

- for (i=1; i<j; i++)

- {

- if(((val[i] = BN_CTX_get(ctx)) == NULL) ||

- !BN_mod_mul_reciprocal(val[i],val[i-1],

- aa,&recp,ctx))

- goto err;

- }

- start=1; /* This is used to avoid multiplication etc

- * when there is only the value '1' in the

- * buffer. */

- wvalue=0; /* The 'value' of the window */

- wstart=bits-1; /* The top bit of the window */

- wend=0; /* The bottom bit of the window */

- if (!BN_one(r)) goto err;

- for (;;)

- {

- if (BN_is_bit_set(p,wstart) == 0)

- {

- if (!start)

- if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))

- goto err;

- if (wstart == 0) break;

- wstart--;

- continue;

- }

- /* We now have wstart on a 'set' bit, we now need to work out

- * how bit a window to do. To do this we need to scan

- * forward until the last set bit before the end of the

- * window */

- j=wstart;

- wvalue=1;

- wend=0;

- for (i=1; i<window; i++)

- {

- if (wstart-i < 0) break;

- if (BN_is_bit_set(p,wstart-i))

- {

- wvalue<<=(i-wend);

- wvalue|=1;

- wend=i;

- }

- /* wend is the size of the current window */

- j=wend+1;

- /* add the 'bytes above' */

- if (!start)

- for (i=0; i<j; i++)

- {

- if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))

- goto err;

- }

- /* wvalue will be an odd number < 2^window */

- if (!BN_mod_mul_reciprocal(r,r,val[wvalue>>1],&recp,ctx))

- goto err;

- /* move the 'window' down further */

- wstart-=wend+1;

- wvalue=0;

- start=0;

- if (wstart < 0) break;

- }

- ret=1;

-err:

- BN_CTX_end(ctx);

- BN_RECP_CTX_free(&recp);

- bn_check_top(r);

- return(ret);

- }

-int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,

- const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)

- {

- int i,j,bits,ret=0,wstart,wend,window,wvalue;

- int start=1;

- BIGNUM *d,*r;

- const BIGNUM *aa;

- /* Table of variables obtained from 'ctx' */

- BIGNUM *val[TABLE_SIZE];

- BN_MONT_CTX *mont=NULL;

- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)

- {

- return BN_mod_exp_mont_consttime(rr, a, p, m, ctx, in_mont);

- }

- bn_check_top(a);

- bn_check_top(p);

- bn_check_top(m);

- if (!BN_is_odd(m))

- {

- BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);

- return(0);

- }

- bits=BN_num_bits(p);

- if (bits == 0)

- {

- ret = BN_one(rr);

- return ret;

- }

- BN_CTX_start(ctx);

- d = BN_CTX_get(ctx);

- r = BN_CTX_get(ctx);

- val[0] = BN_CTX_get(ctx);

- if (!d || !r || !val[0]) goto err;

- /* If this is not done, things will break in the montgomery

- * part */

- if (in_mont != NULL)

- mont=in_mont;

- else

- {

- if ((mont=BN_MONT_CTX_new()) == NULL) goto err;

- if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;

- }

- if (a->neg || BN_ucmp(a,m) >= 0)

- {

- if (!BN_nnmod(val[0],a,m,ctx))

- goto err;

- aa= val[0];

- }

- else

- aa=a;

- if (BN_is_zero(aa))

- {

- BN_zero(rr);

- ret = 1;

- goto err;

- }

- if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */

- window = BN_window_bits_for_exponent_size(bits);

- if (window > 1)

- {

- if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */

- j=1<<(window-1);

- for (i=1; i<j; i++)

- {

- if(((val[i] = BN_CTX_get(ctx)) == NULL) ||

- !BN_mod_mul_montgomery(val[i],val[i-1],

- d,mont,ctx))

- goto err;

- }

- start=1; /* This is used to avoid multiplication etc

- * when there is only the value '1' in the

- * buffer. */

- wvalue=0; /* The 'value' of the window */

- wstart=bits-1; /* The top bit of the window */

- wend=0; /* The bottom bit of the window */

- if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;

- for (;;)

- {

- if (BN_is_bit_set(p,wstart) == 0)

- {

- if (!start)

- {

- if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))

- goto err;

- }

- if (wstart == 0) break;

- wstart--;

- continue;

- }

- /* We now have wstart on a 'set' bit, we now need to work out

- * how bit a window to do. To do this we need to scan

- * forward until the last set bit before the end of the

- * window */

- j=wstart;

- wvalue=1;

- wend=0;

- for (i=1; i<window; i++)

- {

- if (wstart-i < 0) break;

- if (BN_is_bit_set(p,wstart-i))

- {

- wvalue<<=(i-wend);

- wvalue|=1;

- wend=i;

- }

- /* wend is the size of the current window */

- j=wend+1;

- /* add the 'bytes above' */

- if (!start)

- for (i=0; i<j; i++)

- {

- if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))

- goto err;

- }

- /* wvalue will be an odd number < 2^window */

- if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx))

- goto err;

- /* move the 'window' down further */

- wstart-=wend+1;

- wvalue=0;

- start=0;

- if (wstart < 0) break;

- }

- if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;

- ret=1;

-err:

- if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);

- BN_CTX_end(ctx);

- bn_check_top(rr);

- return(ret);

- }

-/* BN_mod_exp_mont_consttime() stores the precomputed powers in a specific layout

- * so that accessing any of these table values shows the same access pattern as far

- * as cache lines are concerned. The following functions are used to transfer a BIGNUM

- * from/to that table. */

-static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top, unsigned char *buf, int idx, int width)

- {

- size_t i, j;

- if (top > b->top)

- top = b->top; /* this works because 'buf' is explicitly zeroed */

- for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)

- {

- buf[j] = ((unsigned char*)b->d)[i];

- }

- return 1;

- }

-static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width)

- {

- size_t i, j;

- if (bn_wexpand(b, top) == NULL)

- return 0;

- for (i=0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)

- {

- ((unsigned char*)b->d)[i] = buf[j];

- }

- b->top = top;

- bn_correct_top(b);

- return 1;

- }

-/* Given a pointer value, compute the next address that is a cache line multiple. */

-#define MOD_EXP_CTIME_ALIGN(x_) \

- ((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK))))

-/* This variant of BN_mod_exp_mont() uses fixed windows and the special

- * precomputation memory layout to limit data-dependency to a minimum

- * to protect secret exponents (cf. the hyper-threading timing attacks

- * pointed out by Colin Percival,

- * http://www.daemonology.net/hyperthreading-considered-harmful/)

- */

-int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,

- const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)

- {

- int i,bits,ret=0,window,wvalue;

- int top;

- BN_MONT_CTX *mont=NULL;

- int numPowers;

- unsigned char *powerbufFree=NULL;

- int powerbufLen = 0;

- unsigned char *powerbuf=NULL;

- BIGNUM tmp, am;

- bn_check_top(a);

- bn_check_top(p);

- bn_check_top(m);

- top = m->top;

- if (!(m->d[0] & 1))

- {

- BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME,BN_R_CALLED_WITH_EVEN_MODULUS);

- return(0);

- }

- bits=BN_num_bits(p);

- if (bits == 0)

- {

- ret = BN_one(rr);

- return ret;

- }

- BN_CTX_start(ctx);

- /* Allocate a montgomery context if it was not supplied by the caller.

- * If this is not done, things will break in the montgomery part.

- */

- if (in_mont != NULL)

- mont=in_mont;

- else

- {

- if ((mont=BN_MONT_CTX_new()) == NULL) goto err;

- if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;

- }

- /* Get the window size to use with size of p. */

- window = BN_window_bits_for_ctime_exponent_size(bits);

-#if defined(OPENSSL_BN_ASM_MONT5)

- if (window==6 && bits<=1024) window=5; /* ~5% improvement of 2048-bit RSA sign */

-#endif

- /* Allocate a buffer large enough to hold all of the pre-computed

- * powers of am, am itself and tmp.

- */

- numPowers = 1 << window;

- powerbufLen = sizeof(m->d[0])*(top*numPowers +

- ((2*top)>numPowers?(2*top):numPowers));

-#ifdef alloca

- if (powerbufLen < 3072)

- powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);

- else

-#endif

- if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)

- goto err;

- powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);

- memset(powerbuf, 0, powerbufLen);

-#ifdef alloca

- if (powerbufLen < 3072)

- powerbufFree = NULL;

-#endif

- /* lay down tmp and am right after powers table */

- tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);

- am.d = tmp.d + top;

- tmp.top = am.top = 0;

- tmp.dmax = am.dmax = top;

- tmp.neg = am.neg = 0;

- tmp.flags = am.flags = BN_FLG_STATIC_DATA;

- /* prepare a^0 in Montgomery domain */

-#if 1

- if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx)) goto err;

-#else

- tmp.d[0] = (0-m->d[0])&BN_MASK2; /* 2^(top*BN_BITS2) - m */

- for (i=1;i<top;i++)

- tmp.d[i] = (~m->d[i])&BN_MASK2;

- tmp.top = top;

-#endif

- /* prepare a^1 in Montgomery domain */

- if (a->neg || BN_ucmp(a,m) >= 0)

- {

- if (!BN_mod(&am,a,m,ctx)) goto err;

- if (!BN_to_montgomery(&am,&am,mont,ctx)) goto err;

- }

- else if (!BN_to_montgomery(&am,a,mont,ctx)) goto err;

-#if defined(OPENSSL_BN_ASM_MONT5)

- /* This optimization uses ideas from http://eprint.iacr.org/2011/239,

- * specifically optimization of cache-timing attack countermeasures

- * and pre-computation optimization. */

- /* Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as

- * 512-bit RSA is hardly relevant, we omit it to spare size... */

- if (window==5)

- {

- void bn_mul_mont_gather5(BN_ULONG *rp,const BN_ULONG *ap,

- const void *table,const BN_ULONG *np,

- const BN_ULONG *n0,int num,int power);

- void bn_scatter5(const BN_ULONG *inp,size_t num,

- void *table,size_t power);

- void bn_gather5(BN_ULONG *out,size_t num,

- void *table,size_t power);

- BN_ULONG *np=mont->N.d, *n0=mont->n0;

- /* BN_to_montgomery can contaminate words above .top

- * [in BN_DEBUG[_DEBUG] build]... */

- for (i=am.top; i<top; i++) am.d[i]=0;

- for (i=tmp.top; i<top; i++) tmp.d[i]=0;

- bn_scatter5(tmp.d,top,powerbuf,0);

- bn_scatter5(am.d,am.top,powerbuf,1);

- bn_mul_mont(tmp.d,am.d,am.d,np,n0,top);

- bn_scatter5(tmp.d,top,powerbuf,2);

-#if 0

- for (i=3; i<32; i++)

- {

- /* Calculate a^i = a^(i-1) * a */

- bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);

- bn_scatter5(tmp.d,top,powerbuf,i);

- }

-#else

- /* same as above, but uses squaring for 1/2 of operations */

- for (i=4; i<32; i*=2)

- {

- bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);

- bn_scatter5(tmp.d,top,powerbuf,i);

- }

- for (i=3; i<8; i+=2)

- {

- int j;

- bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);

- bn_scatter5(tmp.d,top,powerbuf,i);

- for (j=2*i; j<32; j*=2)

- {

- bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);

- bn_scatter5(tmp.d,top,powerbuf,j);

- }

- for (; i<16; i+=2)

- {

- bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);

- bn_scatter5(tmp.d,top,powerbuf,i);

- bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);

- bn_scatter5(tmp.d,top,powerbuf,2*i);

- }

- for (; i<32; i+=2)

- {

- bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);

- bn_scatter5(tmp.d,top,powerbuf,i);

- }

-#endif

- bits--;

- for (wvalue=0, i=bits%5; i>=0; i--,bits--)

- wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);

- bn_gather5(tmp.d,top,powerbuf,wvalue);

- /* Scan the exponent one window at a time starting from the most

- * significant bits.

- */

- while (bits >= 0)

- {

- for (wvalue=0, i=0; i<5; i++,bits--)

- wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);

- bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);

- bn_mul_mont_gather5(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);

- }

- tmp.top=top;

- bn_correct_top(&tmp);

- }

- else

-#endif

- {

- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, numPowers)) goto err;

- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, numPowers)) goto err;

- /* If the window size is greater than 1, then calculate

- * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)

- * (even powers could instead be computed as (a^(i/2))^2

- * to use the slight performance advantage of sqr over mul).

- */

- if (window > 1)

- {

- if (!BN_mod_mul_montgomery(&tmp,&am,&am,mont,ctx)) goto err;

- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, numPowers)) goto err;

- for (i=3; i<numPowers; i++)

- {

- /* Calculate a^i = a^(i-1) * a */

- if (!BN_mod_mul_montgomery(&tmp,&am,&tmp,mont,ctx))

- goto err;

- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, numPowers)) goto err;

- }

- bits--;

- for (wvalue=0, i=bits%window; i>=0; i--,bits--)

- wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);

- if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp,top,powerbuf,wvalue,numPowers)) goto err;

- /* Scan the exponent one window at a time starting from the most

- * significant bits.

- */

- while (bits >= 0)

- {

- wvalue=0; /* The 'value' of the window */

- /* Scan the window, squaring the result as we go */

- for (i=0; i<window; i++,bits--)

- {

- if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx)) goto err;

- wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);

- }

- /* Fetch the appropriate pre-computed value from the pre-buf */

- if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue, numPowers)) goto err;

- /* Multiply the result into the intermediate result */

- if (!BN_mod_mul_montgomery(&tmp,&tmp,&am,mont,ctx)) goto err;

- }

- /* Convert the final result from montgomery to standard format */

- if (!BN_from_montgomery(rr,&tmp,mont,ctx)) goto err;

- ret=1;

-err:

- if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);

- if (powerbuf!=NULL)

- {

- OPENSSL_cleanse(powerbuf,powerbufLen);

- if (powerbufFree) OPENSSL_free(powerbufFree);

- }

- BN_CTX_end(ctx);

- return(ret);

- }

-int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,

- const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)

- {

- BN_MONT_CTX *mont = NULL;

- int b, bits, ret=0;

- int r_is_one;

- BN_ULONG w, next_w;

- BIGNUM *d, *r, *t;

- BIGNUM *swap_tmp;

-#define BN_MOD_MUL_WORD(r, w, m) \

- (BN_mul_word(r, (w)) && \

- (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \

- (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))

- /* BN_MOD_MUL_WORD is only used with 'w' large,

- * so the BN_ucmp test is probably more overhead

- * than always using BN_mod (which uses BN_copy if

- * a similar test returns true). */

- /* We can use BN_mod and do not need BN_nnmod because our

- * accumulator is never negative (the result of BN_mod does

- * not depend on the sign of the modulus).

- */

-#define BN_TO_MONTGOMERY_WORD(r, w, mont) \

- (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))

- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)

- {

- /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */

- BNerr(BN_F_BN_MOD_EXP_MONT_WORD,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

- return -1;

- }

- bn_check_top(p);

- bn_check_top(m);

- if (!BN_is_odd(m))

- {

- BNerr(BN_F_BN_MOD_EXP_MONT_WORD,BN_R_CALLED_WITH_EVEN_MODULUS);

- return(0);

- }

- if (m->top == 1)

- a %= m->d[0]; /* make sure that 'a' is reduced */

- bits = BN_num_bits(p);

- if (bits == 0)

- {

- ret = BN_one(rr);

- return ret;

- }

- if (a == 0)

- {

- BN_zero(rr);

- ret = 1;

- return ret;

- }

- BN_CTX_start(ctx);

- d = BN_CTX_get(ctx);

- r = BN_CTX_get(ctx);

- t = BN_CTX_get(ctx);

- if (d == NULL || r == NULL || t == NULL) goto err;

- if (in_mont != NULL)

- mont=in_mont;

- else

- {

- if ((mont = BN_MONT_CTX_new()) == NULL) goto err;

- if (!BN_MONT_CTX_set(mont, m, ctx)) goto err;

- }

- r_is_one = 1; /* except for Montgomery factor */

- /* bits-1 >= 0 */

- /* The result is accumulated in the product r*w. */

- w = a; /* bit 'bits-1' of 'p' is always set */

- for (b = bits-2; b >= 0; b--)

- {

- /* First, square r*w. */

- next_w = w*w;

- if ((next_w/w) != w) /* overflow */

- {

- if (r_is_one)

- {

- if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;

- r_is_one = 0;

- }

- else

- {

- if (!BN_MOD_MUL_WORD(r, w, m)) goto err;

- }

- next_w = 1;

- }

- w = next_w;

- if (!r_is_one)

- {

- if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) goto err;

- }

- /* Second, multiply r*w by 'a' if exponent bit is set. */

- if (BN_is_bit_set(p, b))

- {

- next_w = w*a;

- if ((next_w/a) != w) /* overflow */

- {

- if (r_is_one)

- {

- if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;

- r_is_one = 0;

- }

- else

- {

- if (!BN_MOD_MUL_WORD(r, w, m)) goto err;

- }

- next_w = a;

- }

- w = next_w;

- }

- /* Finally, set r:=r*w. */

- if (w != 1)

- {

- if (r_is_one)

- {

- if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;

- r_is_one = 0;

- }

- else

- {

- if (!BN_MOD_MUL_WORD(r, w, m)) goto err;

- }

- if (r_is_one) /* can happen only if a == 1*/

- {

- if (!BN_one(rr)) goto err;

- }

- else

- {

- if (!BN_from_montgomery(rr, r, mont, ctx)) goto err;

- }

- ret = 1;

-err:

- if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);

- BN_CTX_end(ctx);

- bn_check_top(rr);

- return(ret);

- }

-/* The old fallback, simple version :-) */

-int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

- const BIGNUM *m, BN_CTX *ctx)

- {

- int i,j,bits,ret=0,wstart,wend,window,wvalue;

- int start=1;

- BIGNUM *d;

- /* Table of variables obtained from 'ctx' */

- BIGNUM *val[TABLE_SIZE];

- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0)

- {

- /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */

- BNerr(BN_F_BN_MOD_EXP_SIMPLE,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

- return -1;

- }

- bits=BN_num_bits(p);

- if (bits == 0)

- {

- ret = BN_one(r);

- return ret;

- }

- BN_CTX_start(ctx);

- d = BN_CTX_get(ctx);

- val[0] = BN_CTX_get(ctx);

- if(!d || !val[0]) goto err;

- if (!BN_nnmod(val[0],a,m,ctx)) goto err; /* 1 */

- if (BN_is_zero(val[0]))

- {

- BN_zero(r);

- ret = 1;

- goto err;

- }

- window = BN_window_bits_for_exponent_size(bits);

- if (window > 1)

- {

- if (!BN_mod_mul(d,val[0],val[0],m,ctx))

- goto err; /* 2 */

- j=1<<(window-1);

- for (i=1; i<j; i++)

- {

- if(((val[i] = BN_CTX_get(ctx)) == NULL) ||

- !BN_mod_mul(val[i],val[i-1],d,m,ctx))

- goto err;

- }

- start=1; /* This is used to avoid multiplication etc

- * when there is only the value '1' in the

- * buffer. */

- wvalue=0; /* The 'value' of the window */

- wstart=bits-1; /* The top bit of the window */

- wend=0; /* The bottom bit of the window */

- if (!BN_one(r)) goto err;

- for (;;)

- {

- if (BN_is_bit_set(p,wstart) == 0)

- {

- if (!start)

- if (!BN_mod_mul(r,r,r,m,ctx))

- goto err;

- if (wstart == 0) break;

- wstart--;

- continue;

- }

- /* We now have wstart on a 'set' bit, we now need to work out

- * how bit a window to do. To do this we need to scan

- * forward until the last set bit before the end of the

- * window */

- j=wstart;

- wvalue=1;

- wend=0;

- for (i=1; i<window; i++)

- {

- if (wstart-i < 0) break;

- if (BN_is_bit_set(p,wstart-i))

- {

- wvalue<<=(i-wend);

- wvalue|=1;

- wend=i;

- }

- /* wend is the size of the current window */

- j=wend+1;

- /* add the 'bytes above' */

- if (!start)

- for (i=0; i<j; i++)

- {

- if (!BN_mod_mul(r,r,r,m,ctx))

- goto err;

- }

- /* wvalue will be an odd number < 2^window */

- if (!BN_mod_mul(r,r,val[wvalue>>1],m,ctx))

- goto err;

- /* move the 'window' down further */

- wstart-=wend+1;

- wvalue=0;

- start=0;

- if (wstart < 0) break;

- }

- ret=1;

-err:

- BN_CTX_end(ctx);

- bn_check_top(r);

- return(ret);

- }

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