| Index: openssl/crypto/bn/bn_gcd.c
|
| diff --git a/openssl/crypto/bn/bn_gcd.c b/openssl/crypto/bn/bn_gcd.c
|
| deleted file mode 100644
|
| index a808f53178fb830572a6d8c2edb4eabb5063c844..0000000000000000000000000000000000000000
|
| --- a/openssl/crypto/bn/bn_gcd.c
|
| +++ /dev/null
|
| @@ -1,655 +0,0 @@
|
| -/* crypto/bn/bn_gcd.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) 1998-2001 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 "cryptlib.h"
|
| -#include "bn_lcl.h"
|
| -
|
| -static BIGNUM *euclid(BIGNUM *a, BIGNUM *b);
|
| -
|
| -int BN_gcd(BIGNUM *r, const BIGNUM *in_a, const BIGNUM *in_b, BN_CTX *ctx)
|
| - {
|
| - BIGNUM *a,*b,*t;
|
| - int ret=0;
|
| -
|
| - bn_check_top(in_a);
|
| - bn_check_top(in_b);
|
| -
|
| - BN_CTX_start(ctx);
|
| - a = BN_CTX_get(ctx);
|
| - b = BN_CTX_get(ctx);
|
| - if (a == NULL || b == NULL) goto err;
|
| -
|
| - if (BN_copy(a,in_a) == NULL) goto err;
|
| - if (BN_copy(b,in_b) == NULL) goto err;
|
| - a->neg = 0;
|
| - b->neg = 0;
|
| -
|
| - if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; }
|
| - t=euclid(a,b);
|
| - if (t == NULL) goto err;
|
| -
|
| - if (BN_copy(r,t) == NULL) goto err;
|
| - ret=1;
|
| -err:
|
| - BN_CTX_end(ctx);
|
| - bn_check_top(r);
|
| - return(ret);
|
| - }
|
| -
|
| -static BIGNUM *euclid(BIGNUM *a, BIGNUM *b)
|
| - {
|
| - BIGNUM *t;
|
| - int shifts=0;
|
| -
|
| - bn_check_top(a);
|
| - bn_check_top(b);
|
| -
|
| - /* 0 <= b <= a */
|
| - while (!BN_is_zero(b))
|
| - {
|
| - /* 0 < b <= a */
|
| -
|
| - if (BN_is_odd(a))
|
| - {
|
| - if (BN_is_odd(b))
|
| - {
|
| - if (!BN_sub(a,a,b)) goto err;
|
| - if (!BN_rshift1(a,a)) goto err;
|
| - if (BN_cmp(a,b) < 0)
|
| - { t=a; a=b; b=t; }
|
| - }
|
| - else /* a odd - b even */
|
| - {
|
| - if (!BN_rshift1(b,b)) goto err;
|
| - if (BN_cmp(a,b) < 0)
|
| - { t=a; a=b; b=t; }
|
| - }
|
| - }
|
| - else /* a is even */
|
| - {
|
| - if (BN_is_odd(b))
|
| - {
|
| - if (!BN_rshift1(a,a)) goto err;
|
| - if (BN_cmp(a,b) < 0)
|
| - { t=a; a=b; b=t; }
|
| - }
|
| - else /* a even - b even */
|
| - {
|
| - if (!BN_rshift1(a,a)) goto err;
|
| - if (!BN_rshift1(b,b)) goto err;
|
| - shifts++;
|
| - }
|
| - }
|
| - /* 0 <= b <= a */
|
| - }
|
| -
|
| - if (shifts)
|
| - {
|
| - if (!BN_lshift(a,a,shifts)) goto err;
|
| - }
|
| - bn_check_top(a);
|
| - return(a);
|
| -err:
|
| - return(NULL);
|
| - }
|
| -
|
| -
|
| -/* solves ax == 1 (mod n) */
|
| -static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *in,
|
| - const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx);
|
| -
|
| -BIGNUM *BN_mod_inverse(BIGNUM *in,
|
| - const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
|
| - {
|
| - BIGNUM *A,*B,*X,*Y,*M,*D,*T,*R=NULL;
|
| - BIGNUM *ret=NULL;
|
| - int sign;
|
| -
|
| - if ((BN_get_flags(a, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(n, BN_FLG_CONSTTIME) != 0))
|
| - {
|
| - return BN_mod_inverse_no_branch(in, a, n, ctx);
|
| - }
|
| -
|
| - bn_check_top(a);
|
| - bn_check_top(n);
|
| -
|
| - BN_CTX_start(ctx);
|
| - A = BN_CTX_get(ctx);
|
| - B = BN_CTX_get(ctx);
|
| - X = BN_CTX_get(ctx);
|
| - D = BN_CTX_get(ctx);
|
| - M = BN_CTX_get(ctx);
|
| - Y = BN_CTX_get(ctx);
|
| - T = BN_CTX_get(ctx);
|
| - if (T == NULL) goto err;
|
| -
|
| - if (in == NULL)
|
| - R=BN_new();
|
| - else
|
| - R=in;
|
| - if (R == NULL) goto err;
|
| -
|
| - BN_one(X);
|
| - BN_zero(Y);
|
| - if (BN_copy(B,a) == NULL) goto err;
|
| - if (BN_copy(A,n) == NULL) goto err;
|
| - A->neg = 0;
|
| - if (B->neg || (BN_ucmp(B, A) >= 0))
|
| - {
|
| - if (!BN_nnmod(B, B, A, ctx)) goto err;
|
| - }
|
| - sign = -1;
|
| - /* From B = a mod |n|, A = |n| it follows that
|
| - *
|
| - * 0 <= B < A,
|
| - * -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|).
|
| - */
|
| -
|
| - if (BN_is_odd(n) && (BN_num_bits(n) <= (BN_BITS <= 32 ? 450 : 2048)))
|
| - {
|
| - /* Binary inversion algorithm; requires odd modulus.
|
| - * This is faster than the general algorithm if the modulus
|
| - * is sufficiently small (about 400 .. 500 bits on 32-bit
|
| - * sytems, but much more on 64-bit systems) */
|
| - int shift;
|
| -
|
| - while (!BN_is_zero(B))
|
| - {
|
| - /*
|
| - * 0 < B < |n|,
|
| - * 0 < A <= |n|,
|
| - * (1) -sign*X*a == B (mod |n|),
|
| - * (2) sign*Y*a == A (mod |n|)
|
| - */
|
| -
|
| - /* Now divide B by the maximum possible power of two in the integers,
|
| - * and divide X by the same value mod |n|.
|
| - * When we're done, (1) still holds. */
|
| - shift = 0;
|
| - while (!BN_is_bit_set(B, shift)) /* note that 0 < B */
|
| - {
|
| - shift++;
|
| -
|
| - if (BN_is_odd(X))
|
| - {
|
| - if (!BN_uadd(X, X, n)) goto err;
|
| - }
|
| - /* now X is even, so we can easily divide it by two */
|
| - if (!BN_rshift1(X, X)) goto err;
|
| - }
|
| - if (shift > 0)
|
| - {
|
| - if (!BN_rshift(B, B, shift)) goto err;
|
| - }
|
| -
|
| -
|
| - /* Same for A and Y. Afterwards, (2) still holds. */
|
| - shift = 0;
|
| - while (!BN_is_bit_set(A, shift)) /* note that 0 < A */
|
| - {
|
| - shift++;
|
| -
|
| - if (BN_is_odd(Y))
|
| - {
|
| - if (!BN_uadd(Y, Y, n)) goto err;
|
| - }
|
| - /* now Y is even */
|
| - if (!BN_rshift1(Y, Y)) goto err;
|
| - }
|
| - if (shift > 0)
|
| - {
|
| - if (!BN_rshift(A, A, shift)) goto err;
|
| - }
|
| -
|
| -
|
| - /* We still have (1) and (2).
|
| - * Both A and B are odd.
|
| - * The following computations ensure that
|
| - *
|
| - * 0 <= B < |n|,
|
| - * 0 < A < |n|,
|
| - * (1) -sign*X*a == B (mod |n|),
|
| - * (2) sign*Y*a == A (mod |n|),
|
| - *
|
| - * and that either A or B is even in the next iteration.
|
| - */
|
| - if (BN_ucmp(B, A) >= 0)
|
| - {
|
| - /* -sign*(X + Y)*a == B - A (mod |n|) */
|
| - if (!BN_uadd(X, X, Y)) goto err;
|
| - /* NB: we could use BN_mod_add_quick(X, X, Y, n), but that
|
| - * actually makes the algorithm slower */
|
| - if (!BN_usub(B, B, A)) goto err;
|
| - }
|
| - else
|
| - {
|
| - /* sign*(X + Y)*a == A - B (mod |n|) */
|
| - if (!BN_uadd(Y, Y, X)) goto err;
|
| - /* as above, BN_mod_add_quick(Y, Y, X, n) would slow things down */
|
| - if (!BN_usub(A, A, B)) goto err;
|
| - }
|
| - }
|
| - }
|
| - else
|
| - {
|
| - /* general inversion algorithm */
|
| -
|
| - while (!BN_is_zero(B))
|
| - {
|
| - BIGNUM *tmp;
|
| -
|
| - /*
|
| - * 0 < B < A,
|
| - * (*) -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|)
|
| - */
|
| -
|
| - /* (D, M) := (A/B, A%B) ... */
|
| - if (BN_num_bits(A) == BN_num_bits(B))
|
| - {
|
| - if (!BN_one(D)) goto err;
|
| - if (!BN_sub(M,A,B)) goto err;
|
| - }
|
| - else if (BN_num_bits(A) == BN_num_bits(B) + 1)
|
| - {
|
| - /* A/B is 1, 2, or 3 */
|
| - if (!BN_lshift1(T,B)) goto err;
|
| - if (BN_ucmp(A,T) < 0)
|
| - {
|
| - /* A < 2*B, so D=1 */
|
| - if (!BN_one(D)) goto err;
|
| - if (!BN_sub(M,A,B)) goto err;
|
| - }
|
| - else
|
| - {
|
| - /* A >= 2*B, so D=2 or D=3 */
|
| - if (!BN_sub(M,A,T)) goto err;
|
| - if (!BN_add(D,T,B)) goto err; /* use D (:= 3*B) as temp */
|
| - if (BN_ucmp(A,D) < 0)
|
| - {
|
| - /* A < 3*B, so D=2 */
|
| - if (!BN_set_word(D,2)) goto err;
|
| - /* M (= A - 2*B) already has the correct value */
|
| - }
|
| - else
|
| - {
|
| - /* only D=3 remains */
|
| - if (!BN_set_word(D,3)) goto err;
|
| - /* currently M = A - 2*B, but we need M = A - 3*B */
|
| - if (!BN_sub(M,M,B)) goto err;
|
| - }
|
| - }
|
| - }
|
| - else
|
| - {
|
| - if (!BN_div(D,M,A,B,ctx)) goto err;
|
| - }
|
| -
|
| - /* Now
|
| - * A = D*B + M;
|
| - * thus we have
|
| - * (**) sign*Y*a == D*B + M (mod |n|).
|
| - */
|
| -
|
| - tmp=A; /* keep the BIGNUM object, the value does not matter */
|
| -
|
| - /* (A, B) := (B, A mod B) ... */
|
| - A=B;
|
| - B=M;
|
| - /* ... so we have 0 <= B < A again */
|
| -
|
| - /* Since the former M is now B and the former B is now A,
|
| - * (**) translates into
|
| - * sign*Y*a == D*A + B (mod |n|),
|
| - * i.e.
|
| - * sign*Y*a - D*A == B (mod |n|).
|
| - * Similarly, (*) translates into
|
| - * -sign*X*a == A (mod |n|).
|
| - *
|
| - * Thus,
|
| - * sign*Y*a + D*sign*X*a == B (mod |n|),
|
| - * i.e.
|
| - * sign*(Y + D*X)*a == B (mod |n|).
|
| - *
|
| - * So if we set (X, Y, sign) := (Y + D*X, X, -sign), we arrive back at
|
| - * -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|).
|
| - * Note that X and Y stay non-negative all the time.
|
| - */
|
| -
|
| - /* most of the time D is very small, so we can optimize tmp := D*X+Y */
|
| - if (BN_is_one(D))
|
| - {
|
| - if (!BN_add(tmp,X,Y)) goto err;
|
| - }
|
| - else
|
| - {
|
| - if (BN_is_word(D,2))
|
| - {
|
| - if (!BN_lshift1(tmp,X)) goto err;
|
| - }
|
| - else if (BN_is_word(D,4))
|
| - {
|
| - if (!BN_lshift(tmp,X,2)) goto err;
|
| - }
|
| - else if (D->top == 1)
|
| - {
|
| - if (!BN_copy(tmp,X)) goto err;
|
| - if (!BN_mul_word(tmp,D->d[0])) goto err;
|
| - }
|
| - else
|
| - {
|
| - if (!BN_mul(tmp,D,X,ctx)) goto err;
|
| - }
|
| - if (!BN_add(tmp,tmp,Y)) goto err;
|
| - }
|
| -
|
| - M=Y; /* keep the BIGNUM object, the value does not matter */
|
| - Y=X;
|
| - X=tmp;
|
| - sign = -sign;
|
| - }
|
| - }
|
| -
|
| - /*
|
| - * The while loop (Euclid's algorithm) ends when
|
| - * A == gcd(a,n);
|
| - * we have
|
| - * sign*Y*a == A (mod |n|),
|
| - * where Y is non-negative.
|
| - */
|
| -
|
| - if (sign < 0)
|
| - {
|
| - if (!BN_sub(Y,n,Y)) goto err;
|
| - }
|
| - /* Now Y*a == A (mod |n|). */
|
| -
|
| -
|
| - if (BN_is_one(A))
|
| - {
|
| - /* Y*a == 1 (mod |n|) */
|
| - if (!Y->neg && BN_ucmp(Y,n) < 0)
|
| - {
|
| - if (!BN_copy(R,Y)) goto err;
|
| - }
|
| - else
|
| - {
|
| - if (!BN_nnmod(R,Y,n,ctx)) goto err;
|
| - }
|
| - }
|
| - else
|
| - {
|
| - BNerr(BN_F_BN_MOD_INVERSE,BN_R_NO_INVERSE);
|
| - goto err;
|
| - }
|
| - ret=R;
|
| -err:
|
| - if ((ret == NULL) && (in == NULL)) BN_free(R);
|
| - BN_CTX_end(ctx);
|
| - bn_check_top(ret);
|
| - return(ret);
|
| - }
|
| -
|
| -
|
| -/* BN_mod_inverse_no_branch is a special version of BN_mod_inverse.
|
| - * It does not contain branches that may leak sensitive information.
|
| - */
|
| -static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *in,
|
| - const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
|
| - {
|
| - BIGNUM *A,*B,*X,*Y,*M,*D,*T,*R=NULL;
|
| - BIGNUM local_A, local_B;
|
| - BIGNUM *pA, *pB;
|
| - BIGNUM *ret=NULL;
|
| - int sign;
|
| -
|
| - bn_check_top(a);
|
| - bn_check_top(n);
|
| -
|
| - BN_CTX_start(ctx);
|
| - A = BN_CTX_get(ctx);
|
| - B = BN_CTX_get(ctx);
|
| - X = BN_CTX_get(ctx);
|
| - D = BN_CTX_get(ctx);
|
| - M = BN_CTX_get(ctx);
|
| - Y = BN_CTX_get(ctx);
|
| - T = BN_CTX_get(ctx);
|
| - if (T == NULL) goto err;
|
| -
|
| - if (in == NULL)
|
| - R=BN_new();
|
| - else
|
| - R=in;
|
| - if (R == NULL) goto err;
|
| -
|
| - BN_one(X);
|
| - BN_zero(Y);
|
| - if (BN_copy(B,a) == NULL) goto err;
|
| - if (BN_copy(A,n) == NULL) goto err;
|
| - A->neg = 0;
|
| -
|
| - if (B->neg || (BN_ucmp(B, A) >= 0))
|
| - {
|
| - /* Turn BN_FLG_CONSTTIME flag on, so that when BN_div is invoked,
|
| - * BN_div_no_branch will be called eventually.
|
| - */
|
| - pB = &local_B;
|
| - BN_with_flags(pB, B, BN_FLG_CONSTTIME);
|
| - if (!BN_nnmod(B, pB, A, ctx)) goto err;
|
| - }
|
| - sign = -1;
|
| - /* From B = a mod |n|, A = |n| it follows that
|
| - *
|
| - * 0 <= B < A,
|
| - * -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|).
|
| - */
|
| -
|
| - while (!BN_is_zero(B))
|
| - {
|
| - BIGNUM *tmp;
|
| -
|
| - /*
|
| - * 0 < B < A,
|
| - * (*) -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|)
|
| - */
|
| -
|
| - /* Turn BN_FLG_CONSTTIME flag on, so that when BN_div is invoked,
|
| - * BN_div_no_branch will be called eventually.
|
| - */
|
| - pA = &local_A;
|
| - BN_with_flags(pA, A, BN_FLG_CONSTTIME);
|
| -
|
| - /* (D, M) := (A/B, A%B) ... */
|
| - if (!BN_div(D,M,pA,B,ctx)) goto err;
|
| -
|
| - /* Now
|
| - * A = D*B + M;
|
| - * thus we have
|
| - * (**) sign*Y*a == D*B + M (mod |n|).
|
| - */
|
| -
|
| - tmp=A; /* keep the BIGNUM object, the value does not matter */
|
| -
|
| - /* (A, B) := (B, A mod B) ... */
|
| - A=B;
|
| - B=M;
|
| - /* ... so we have 0 <= B < A again */
|
| -
|
| - /* Since the former M is now B and the former B is now A,
|
| - * (**) translates into
|
| - * sign*Y*a == D*A + B (mod |n|),
|
| - * i.e.
|
| - * sign*Y*a - D*A == B (mod |n|).
|
| - * Similarly, (*) translates into
|
| - * -sign*X*a == A (mod |n|).
|
| - *
|
| - * Thus,
|
| - * sign*Y*a + D*sign*X*a == B (mod |n|),
|
| - * i.e.
|
| - * sign*(Y + D*X)*a == B (mod |n|).
|
| - *
|
| - * So if we set (X, Y, sign) := (Y + D*X, X, -sign), we arrive back at
|
| - * -sign*X*a == B (mod |n|),
|
| - * sign*Y*a == A (mod |n|).
|
| - * Note that X and Y stay non-negative all the time.
|
| - */
|
| -
|
| - if (!BN_mul(tmp,D,X,ctx)) goto err;
|
| - if (!BN_add(tmp,tmp,Y)) goto err;
|
| -
|
| - M=Y; /* keep the BIGNUM object, the value does not matter */
|
| - Y=X;
|
| - X=tmp;
|
| - sign = -sign;
|
| - }
|
| -
|
| - /*
|
| - * The while loop (Euclid's algorithm) ends when
|
| - * A == gcd(a,n);
|
| - * we have
|
| - * sign*Y*a == A (mod |n|),
|
| - * where Y is non-negative.
|
| - */
|
| -
|
| - if (sign < 0)
|
| - {
|
| - if (!BN_sub(Y,n,Y)) goto err;
|
| - }
|
| - /* Now Y*a == A (mod |n|). */
|
| -
|
| - if (BN_is_one(A))
|
| - {
|
| - /* Y*a == 1 (mod |n|) */
|
| - if (!Y->neg && BN_ucmp(Y,n) < 0)
|
| - {
|
| - if (!BN_copy(R,Y)) goto err;
|
| - }
|
| - else
|
| - {
|
| - if (!BN_nnmod(R,Y,n,ctx)) goto err;
|
| - }
|
| - }
|
| - else
|
| - {
|
| - BNerr(BN_F_BN_MOD_INVERSE_NO_BRANCH,BN_R_NO_INVERSE);
|
| - goto err;
|
| - }
|
| - ret=R;
|
| -err:
|
| - if ((ret == NULL) && (in == NULL)) BN_free(R);
|
| - BN_CTX_end(ctx);
|
| - bn_check_top(ret);
|
| - return(ret);
|
| - }
|
|
|