diff options
Diffstat (limited to 'openssl/crypto/bn/bn_recp.c')
| -rw-r--r-- | openssl/crypto/bn/bn_recp.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/openssl/crypto/bn/bn_recp.c b/openssl/crypto/bn/bn_recp.c new file mode 100644 index 000000000..2e8efb8da --- /dev/null +++ b/openssl/crypto/bn/bn_recp.c @@ -0,0 +1,234 @@ +/* crypto/bn/bn_recp.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.] + */ + +#include <stdio.h> +#include "cryptlib.h" +#include "bn_lcl.h" + +void BN_RECP_CTX_init(BN_RECP_CTX *recp) + { + BN_init(&(recp->N)); + BN_init(&(recp->Nr)); + recp->num_bits=0; + recp->flags=0; + } + +BN_RECP_CTX *BN_RECP_CTX_new(void) + { + BN_RECP_CTX *ret; + + if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL) + return(NULL); + + BN_RECP_CTX_init(ret); + ret->flags=BN_FLG_MALLOCED; + return(ret); + } + +void BN_RECP_CTX_free(BN_RECP_CTX *recp) + { + if(recp == NULL) + return; + + BN_free(&(recp->N)); + BN_free(&(recp->Nr)); + if (recp->flags & BN_FLG_MALLOCED) + OPENSSL_free(recp); + } + +int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx) + { + if (!BN_copy(&(recp->N),d)) return 0; + BN_zero(&(recp->Nr)); + recp->num_bits=BN_num_bits(d); + recp->shift=0; + return(1); + } + +int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y, + BN_RECP_CTX *recp, BN_CTX *ctx) + { + int ret=0; + BIGNUM *a; + const BIGNUM *ca; + + BN_CTX_start(ctx); + if ((a = BN_CTX_get(ctx)) == NULL) goto err; + if (y != NULL) + { + if (x == y) + { if (!BN_sqr(a,x,ctx)) goto err; } + else + { if (!BN_mul(a,x,y,ctx)) goto err; } + ca = a; + } + else + ca=x; /* Just do the mod */ + + ret = BN_div_recp(NULL,r,ca,recp,ctx); +err: + BN_CTX_end(ctx); + bn_check_top(r); + return(ret); + } + +int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, + BN_RECP_CTX *recp, BN_CTX *ctx) + { + int i,j,ret=0; + BIGNUM *a,*b,*d,*r; + + BN_CTX_start(ctx); + a=BN_CTX_get(ctx); + b=BN_CTX_get(ctx); + if (dv != NULL) + d=dv; + else + d=BN_CTX_get(ctx); + if (rem != NULL) + r=rem; + else + r=BN_CTX_get(ctx); + if (a == NULL || b == NULL || d == NULL || r == NULL) goto err; + + if (BN_ucmp(m,&(recp->N)) < 0) + { + BN_zero(d); + if (!BN_copy(r,m)) return 0; + BN_CTX_end(ctx); + return(1); + } + + /* We want the remainder + * Given input of ABCDEF / ab + * we need multiply ABCDEF by 3 digests of the reciprocal of ab + * + */ + + /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */ + i=BN_num_bits(m); + j=recp->num_bits<<1; + if (j>i) i=j; + + /* Nr := round(2^i / N) */ + if (i != recp->shift) + recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N), + i,ctx); /* BN_reciprocal returns i, or -1 for an error */ + if (recp->shift == -1) goto err; + + /* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))| + * = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))| + * <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)| + * = |m/N| + */ + if (!BN_rshift(a,m,recp->num_bits)) goto err; + if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err; + if (!BN_rshift(d,b,i-recp->num_bits)) goto err; + d->neg=0; + + if (!BN_mul(b,&(recp->N),d,ctx)) goto err; + if (!BN_usub(r,m,b)) goto err; + r->neg=0; + +#if 1 + j=0; + while (BN_ucmp(r,&(recp->N)) >= 0) + { + if (j++ > 2) + { + BNerr(BN_F_BN_DIV_RECP,BN_R_BAD_RECIPROCAL); + goto err; + } + if (!BN_usub(r,r,&(recp->N))) goto err; + if (!BN_add_word(d,1)) goto err; + } +#endif + + r->neg=BN_is_zero(r)?0:m->neg; + d->neg=m->neg^recp->N.neg; + ret=1; +err: + BN_CTX_end(ctx); + bn_check_top(dv); + bn_check_top(rem); + return(ret); + } + +/* len is the expected size of the result + * We actually calculate with an extra word of precision, so + * we can do faster division if the remainder is not required. + */ +/* r := 2^len / m */ +int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx) + { + int ret= -1; + BIGNUM *t; + + BN_CTX_start(ctx); + if((t = BN_CTX_get(ctx)) == NULL) goto err; + + if (!BN_set_bit(t,len)) goto err; + + if (!BN_div(r,NULL,t,m,ctx)) goto err; + + ret=len; +err: + bn_check_top(r); + BN_CTX_end(ctx); + return(ret); + } |