--- /dev/null
+/* 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);
+ }
projects / cassiopeia.git / blobdiff