android / platform / external / openssl / e67c7edd65f69f58535fb358a8665a23e5de62a4 / . / crypto / bn / bn_mod.c

/* crypto/bn/bn_mod.c */ | |

/* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de> | |

* for the OpenSSL project. */ | |

/* ==================================================================== | |

* 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). | |

* | |

*/ | |

/* 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.] | |

*/ | |

#include "cryptlib.h" | |

#include "bn_lcl.h" | |

#if 0 /* now just a #define */ | |

int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) | |

{ | |

return(BN_div(NULL,rem,m,d,ctx)); | |

/* note that rem->neg == m->neg (unless the remainder is zero) */ | |

} | |

#endif | |

int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) | |

{ | |

/* like BN_mod, but returns non-negative remainder | |

* (i.e., 0 <= r < |d| always holds) */ | |

if (!(BN_mod(r,m,d,ctx))) | |

return 0; | |

if (!r->neg) | |

return 1; | |

/* now -|d| < r < 0, so we have to set r := r + |d| */ | |

return (d->neg ? BN_sub : BN_add)(r, r, d); | |

} | |

int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx) | |

{ | |

if (!BN_add(r, a, b)) return 0; | |

return BN_nnmod(r, r, m, ctx); | |

} | |

/* BN_mod_add variant that may be used if both a and b are non-negative | |

* and less than m */ | |

int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m) | |

{ | |

if (!BN_uadd(r, a, b)) return 0; | |

if (BN_ucmp(r, m) >= 0) | |

return BN_usub(r, r, m); | |

return 1; | |

} | |

int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx) | |

{ | |

if (!BN_sub(r, a, b)) return 0; | |

return BN_nnmod(r, r, m, ctx); | |

} | |

/* BN_mod_sub variant that may be used if both a and b are non-negative | |

* and less than m */ | |

int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m) | |

{ | |

if (!BN_sub(r, a, b)) return 0; | |

if (r->neg) | |

return BN_add(r, r, m); | |

return 1; | |

} | |

/* slow but works */ | |

int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, | |

BN_CTX *ctx) | |

{ | |

BIGNUM *t; | |

int ret=0; | |

bn_check_top(a); | |

bn_check_top(b); | |

bn_check_top(m); | |

BN_CTX_start(ctx); | |

if ((t = BN_CTX_get(ctx)) == NULL) goto err; | |

if (a == b) | |

{ if (!BN_sqr(t,a,ctx)) goto err; } | |

else | |

{ if (!BN_mul(t,a,b,ctx)) goto err; } | |

if (!BN_nnmod(r,t,m,ctx)) goto err; | |

bn_check_top(r); | |

ret=1; | |

err: | |

BN_CTX_end(ctx); | |

return(ret); | |

} | |

int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) | |

{ | |

if (!BN_sqr(r, a, ctx)) return 0; | |

/* r->neg == 0, thus we don't need BN_nnmod */ | |

return BN_mod(r, r, m, ctx); | |

} | |

int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) | |

{ | |

if (!BN_lshift1(r, a)) return 0; | |

bn_check_top(r); | |

return BN_nnmod(r, r, m, ctx); | |

} | |

/* BN_mod_lshift1 variant that may be used if a is non-negative | |

* and less than m */ | |

int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m) | |

{ | |

if (!BN_lshift1(r, a)) return 0; | |

bn_check_top(r); | |

if (BN_cmp(r, m) >= 0) | |

return BN_sub(r, r, m); | |

return 1; | |

} | |

int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, BN_CTX *ctx) | |

{ | |

BIGNUM *abs_m = NULL; | |

int ret; | |

if (!BN_nnmod(r, a, m, ctx)) return 0; | |

if (m->neg) | |

{ | |

abs_m = BN_dup(m); | |

if (abs_m == NULL) return 0; | |

abs_m->neg = 0; | |

} | |

ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m)); | |

bn_check_top(r); | |

if (abs_m) | |

BN_free(abs_m); | |

return ret; | |

} | |

/* BN_mod_lshift variant that may be used if a is non-negative | |

* and less than m */ | |

int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m) | |

{ | |

if (r != a) | |

{ | |

if (BN_copy(r, a) == NULL) return 0; | |

} | |

while (n > 0) | |

{ | |

int max_shift; | |

/* 0 < r < m */ | |

max_shift = BN_num_bits(m) - BN_num_bits(r); | |

/* max_shift >= 0 */ | |

if (max_shift < 0) | |

{ | |

BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED); | |

return 0; | |

} | |

if (max_shift > n) | |

max_shift = n; | |

if (max_shift) | |

{ | |

if (!BN_lshift(r, r, max_shift)) return 0; | |

n -= max_shift; | |

} | |

else | |

{ | |

if (!BN_lshift1(r, r)) return 0; | |

--n; | |

} | |

/* BN_num_bits(r) <= BN_num_bits(m) */ | |

if (BN_cmp(r, m) >= 0) | |

{ | |

if (!BN_sub(r, r, m)) return 0; | |

} | |

} | |

bn_check_top(r); | |

return 1; | |

} |