/* 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.
*
* [including the GNU Public Licence.]
*/
-#include <stdio.h>
+#define OPENSSL_FIPSAPI
+
#include "cryptlib.h"
#include "bn_lcl.h"
-/* rem != m */
-int BN_mod(rem, m, d,ctx)
-BIGNUM *rem;
-BIGNUM *m;
-BIGNUM *d;
-BN_CTX *ctx;
+
+#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)
{
-#if 0 /* The old slow way */
- int i,nm,nd;
- BIGNUM *dv;
+ /* 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);
+}
- if (BN_ucmp(m,d) < 0)
- return((BN_copy(rem,m) == NULL)?0:1);
- dv=ctx->bn[ctx->tos];
+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);
+ }
- if (!BN_copy(rem,m)) return(0);
- nm=BN_num_bits(rem);
- nd=BN_num_bits(d);
- if (!BN_lshift(dv,d,nm-nd)) return(0);
- for (i=nm-nd; i>=0; i--)
+/* 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)
{
- if (BN_cmp(rem,dv) >= 0)
+ 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(rem,rem,dv)) return(0);
+ if (!BN_sub(r, r, m)) return 0;
}
- if (!BN_rshift1(dv,dv)) return(0);
}
- return(1);
-#else
- return(BN_div(NULL,rem,m,d,ctx));
-#endif
+ bn_check_top(r);
+
+ return 1;
}
-
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