summaryrefslogtreecommitdiff
path: root/openssl/crypto/bn/bn_exp.c
diff options
context:
space:
mode:
Diffstat (limited to 'openssl/crypto/bn/bn_exp.c')
-rw-r--r--openssl/crypto/bn/bn_exp.c991
1 files changed, 0 insertions, 991 deletions
diff --git a/openssl/crypto/bn/bn_exp.c b/openssl/crypto/bn/bn_exp.c
deleted file mode 100644
index d9b6c737..00000000
--- a/openssl/crypto/bn/bn_exp.c
+++ /dev/null
@@ -1,991 +0,0 @@
-/* crypto/bn/bn_exp.c */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * 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.]
- */
-/* ====================================================================
- * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
- *
- * 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"
-
-/* 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(BIGNUM *b, int top, unsigned char *buf, int idx, int width)
- {
- size_t i, j;
-
- if (bn_wexpand(b, top) == NULL)
- return 0;
- while (b->top < top)
- {
- b->d[b->top++] = 0;
- }
-
- for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
- {
- buf[j] = ((unsigned char*)b->d)[i];
- }
-
- bn_correct_top(b);
- 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 - (((BN_ULONG)(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,idx,window,wvalue;
- int top;
- BIGNUM *r;
- const BIGNUM *aa;
- BN_MONT_CTX *mont=NULL;
-
- int numPowers;
- unsigned char *powerbufFree=NULL;
- int powerbufLen = 0;
- unsigned char *powerbuf=NULL;
- BIGNUM *computeTemp=NULL, *am=NULL;
-
- 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;
- }
-
- /* Initialize BIGNUM context and allocate intermediate result */
- BN_CTX_start(ctx);
- r = BN_CTX_get(ctx);
- if (r == NULL) goto err;
-
- /* 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);
-
- /* Allocate a buffer large enough to hold all of the pre-computed
- * powers of a.
- */
- numPowers = 1 << window;
- powerbufLen = sizeof(m->d[0])*top*numPowers;
- 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);
-
- /* Initialize the intermediate result. Do this early to save double conversion,
- * once each for a^0 and intermediate result.
- */
- if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, numPowers)) goto err;
-
- /* Initialize computeTemp as a^1 with montgomery precalcs */
- computeTemp = BN_CTX_get(ctx);
- am = BN_CTX_get(ctx);
- if (computeTemp==NULL || am==NULL) goto err;
-
- if (a->neg || BN_ucmp(a,m) >= 0)
- {
- if (!BN_mod(am,a,m,ctx))
- goto err;
- aa= am;
- }
- else
- aa=a;
- if (!BN_to_montgomery(am,aa,mont,ctx)) goto err;
- if (!BN_copy(computeTemp, am)) 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)
- {
- for (i=2; i<numPowers; i++)
- {
- /* Calculate a^i = a^(i-1) * a */
- if (!BN_mod_mul_montgomery(computeTemp,am,computeTemp,mont,ctx))
- goto err;
- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(computeTemp, top, powerbuf, i, numPowers)) goto err;
- }
- }
-
- /* Adjust the number of bits up to a multiple of the window size.
- * If the exponent length is not a multiple of the window size, then
- * this pads the most significant bits with zeros to normalize the
- * scanning loop to there's no special cases.
- *
- * * NOTE: Making the window size a power of two less than the native
- * * word size ensures that the padded bits won't go past the last
- * * word in the internal BIGNUM structure. Going past the end will
- * * still produce the correct result, but causes a different branch
- * * to be taken in the BN_is_bit_set function.
- */
- bits = ((bits+window-1)/window)*window;
- idx=bits-1; /* The top bit of the window */
-
- /* Scan the exponent one window at a time starting from the most
- * significant bits.
- */
- while (idx >= 0)
- {
- wvalue=0; /* The 'value' of the window */
-
- /* Scan the window, squaring the result as we go */
- for (i=0; i<window; i++,idx--)
- {
- if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) goto err;
- wvalue = (wvalue<<1)+BN_is_bit_set(p,idx);
- }
-
- /* Fetch the appropriate pre-computed value from the pre-buf */
- if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(computeTemp, top, powerbuf, wvalue, numPowers)) goto err;
-
- /* Multiply the result into the intermediate result */
- if (!BN_mod_mul_montgomery(r,r,computeTemp,mont,ctx)) goto err;
- }
-
- /* Convert the final result from montgomery to standard format */
- if (!BN_from_montgomery(rr,r,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);
- OPENSSL_free(powerbufFree);
- }
- if (am!=NULL) BN_clear(am);
- if (computeTemp!=NULL) BN_clear(computeTemp);
- 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);
- }
-