126 lines
4.6 KiB
C
126 lines
4.6 KiB
C
/* crypto/ec/ec2_smpt.c */
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/* This code was originally written by Douglas Stebila
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* <dstebila@student.math.uwaterloo.ca> for the OpenSSL project.
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*/
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/* ====================================================================
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* Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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/* Calaculates and sets the affine coordinates of an EC_POINT from the given
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* compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
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* Note that the simple implementation only uses affine coordinates.
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*
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* This algorithm is patented by Certicom Corp. under US Patent 6,141,420
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* (for licensing information, contact licensing@certicom.com).
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* This function is disabled by default and can be enabled by defining the
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* preprocessor macro OPENSSL_EC_BIN_PT_COMP at Configure-time.
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*/
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int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
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const BIGNUM *x_, int y_bit, BN_CTX *ctx)
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{
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#ifndef OPENSSL_EC_BIN_PT_COMP
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ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_DISABLED);
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return 0;
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#else
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BN_CTX *new_ctx = NULL;
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BIGNUM *tmp, *x, *y, *z;
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int ret = 0, z0;
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if (ctx == NULL)
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{
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ctx = new_ctx = BN_CTX_new();
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if (ctx == NULL)
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return 0;
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}
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y_bit = (y_bit != 0) ? 1 : 0;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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x = BN_CTX_get(ctx);
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y = BN_CTX_get(ctx);
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z = BN_CTX_get(ctx);
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if (z == NULL) goto err;
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if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err;
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if (BN_is_zero(x))
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{
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if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err;
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}
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else
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{
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if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err;
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if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err;
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if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err;
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if (!BN_GF2m_add(tmp, x, tmp)) goto err;
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if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) goto err;
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z0 = (BN_is_odd(z)) ? 1 : 0;
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if (!group->meth->field_mul(group, y, x, z, ctx)) goto err;
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if (z0 != y_bit)
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{
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if (!BN_GF2m_add(y, y, x)) goto err;
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}
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}
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if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
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ret = 1;
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err:
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BN_CTX_end(ctx);
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if (new_ctx != NULL)
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BN_CTX_free(new_ctx);
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return ret;
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#endif
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}
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