code / widevine-mirrored-source / 66427ffa50c9a1038998509907e91d0be9ced12a / . / openssl-1.0.0a / crypto / bn / bn_exp2.c

/* crypto/bn/bn_exp2.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) 1998-2000 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 <stdio.h> | |

#include "cryptlib.h" | |

#include "bn_lcl.h" | |

#define TABLE_SIZE 32 | |

int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, | |

const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m, | |

BN_CTX *ctx, BN_MONT_CTX *in_mont) | |

{ | |

int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2; | |

int r_is_one=1; | |

BIGNUM *d,*r; | |

const BIGNUM *a_mod_m; | |

/* Tables of variables obtained from 'ctx' */ | |

BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE]; | |

BN_MONT_CTX *mont=NULL; | |

bn_check_top(a1); | |

bn_check_top(p1); | |

bn_check_top(a2); | |

bn_check_top(p2); | |

bn_check_top(m); | |

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

{ | |

BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS); | |

return(0); | |

} | |

bits1=BN_num_bits(p1); | |

bits2=BN_num_bits(p2); | |

if ((bits1 == 0) && (bits2 == 0)) | |

{ | |

ret = BN_one(rr); | |

return ret; | |

} | |

bits=(bits1 > bits2)?bits1:bits2; | |

BN_CTX_start(ctx); | |

d = BN_CTX_get(ctx); | |

r = BN_CTX_get(ctx); | |

val1[0] = BN_CTX_get(ctx); | |

val2[0] = BN_CTX_get(ctx); | |

if(!d || !r || !val1[0] || !val2[0]) 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; | |

} | |

window1 = BN_window_bits_for_exponent_size(bits1); | |

window2 = BN_window_bits_for_exponent_size(bits2); | |

/* | |

* Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1) | |

*/ | |

if (a1->neg || BN_ucmp(a1,m) >= 0) | |

{ | |

if (!BN_mod(val1[0],a1,m,ctx)) | |

goto err; | |

a_mod_m = val1[0]; | |

} | |

else | |

a_mod_m = a1; | |

if (BN_is_zero(a_mod_m)) | |

{ | |

BN_zero(rr); | |

ret = 1; | |

goto err; | |

} | |

if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err; | |

if (window1 > 1) | |

{ | |

if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err; | |

j=1<<(window1-1); | |

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

{ | |

if(((val1[i] = BN_CTX_get(ctx)) == NULL) || | |

!BN_mod_mul_montgomery(val1[i],val1[i-1], | |

d,mont,ctx)) | |

goto err; | |

} | |

} | |

/* | |

* Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1) | |

*/ | |

if (a2->neg || BN_ucmp(a2,m) >= 0) | |

{ | |

if (!BN_mod(val2[0],a2,m,ctx)) | |

goto err; | |

a_mod_m = val2[0]; | |

} | |

else | |

a_mod_m = a2; | |

if (BN_is_zero(a_mod_m)) | |

{ | |

BN_zero(rr); | |

ret = 1; | |

goto err; | |

} | |

if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err; | |

if (window2 > 1) | |

{ | |

if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err; | |

j=1<<(window2-1); | |

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

{ | |

if(((val2[i] = BN_CTX_get(ctx)) == NULL) || | |

!BN_mod_mul_montgomery(val2[i],val2[i-1], | |

d,mont,ctx)) | |

goto err; | |

} | |

} | |

/* Now compute the power product, using independent windows. */ | |

r_is_one=1; | |

wvalue1=0; /* The 'value' of the first window */ | |

wvalue2=0; /* The 'value' of the second window */ | |

wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */ | |

wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */ | |

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

for (b=bits-1; b>=0; b--) | |

{ | |

if (!r_is_one) | |

{ | |

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

goto err; | |

} | |

if (!wvalue1) | |

if (BN_is_bit_set(p1, b)) | |

{ | |

/* consider bits b-window1+1 .. b for this window */ | |

i = b-window1+1; | |

while (!BN_is_bit_set(p1, i)) /* works for i<0 */ | |

i++; | |

wpos1 = i; | |

wvalue1 = 1; | |

for (i = b-1; i >= wpos1; i--) | |

{ | |

wvalue1 <<= 1; | |

if (BN_is_bit_set(p1, i)) | |

wvalue1++; | |

} | |

} | |

if (!wvalue2) | |

if (BN_is_bit_set(p2, b)) | |

{ | |

/* consider bits b-window2+1 .. b for this window */ | |

i = b-window2+1; | |

while (!BN_is_bit_set(p2, i)) | |

i++; | |

wpos2 = i; | |

wvalue2 = 1; | |

for (i = b-1; i >= wpos2; i--) | |

{ | |

wvalue2 <<= 1; | |

if (BN_is_bit_set(p2, i)) | |

wvalue2++; | |

} | |

} | |

if (wvalue1 && b == wpos1) | |

{ | |

/* wvalue1 is odd and < 2^window1 */ | |

if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx)) | |

goto err; | |

wvalue1 = 0; | |

r_is_one = 0; | |

} | |

if (wvalue2 && b == wpos2) | |

{ | |

/* wvalue2 is odd and < 2^window2 */ | |

if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx)) | |

goto err; | |

wvalue2 = 0; | |

r_is_one = 0; | |

} | |

} | |

BN_from_montgomery(rr,r,mont,ctx); | |

ret=1; | |

err: | |

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

BN_CTX_end(ctx); | |

bn_check_top(rr); | |

return(ret); | |

} |