/* crypto/ec/ec2_smpt.c */ /* This code was originally written by Douglas Stebila * <dstebila@student.math.uwaterloo.ca> for the OpenSSL project. */ /* ==================================================================== * Copyright (c) 1998-2002 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). * */ /* Calaculates and sets the affine coordinates of an EC_POINT from the given * compressed coordinates. Uses algorithm 2.3.4 of SEC 1. * Note that the simple implementation only uses affine coordinates. * * This algorithm is patented by Certicom Corp. under US Patent 6,141,420 * (for licensing information, contact licensing@certicom.com). * This function is disabled by default and can be enabled by defining the * preprocessor macro OPENSSL_EC_BIN_PT_COMP at Configure-time. */ int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point, const BIGNUM *x_, int y_bit, BN_CTX *ctx) { #ifndef OPENSSL_EC_BIN_PT_COMP ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_DISABLED); return 0; #else BN_CTX *new_ctx = NULL; BIGNUM *tmp, *x, *y, *z; int ret = 0, z0; /* clear error queue */ ERR_clear_error(); if (ctx == NULL) { ctx = new_ctx = BN_CTX_new(); if (ctx == NULL) return 0; } y_bit = (y_bit != 0) ? 1 : 0; BN_CTX_start(ctx); tmp = BN_CTX_get(ctx); x = BN_CTX_get(ctx); y = BN_CTX_get(ctx); z = BN_CTX_get(ctx); if (z == NULL) goto err; if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err; if (BN_is_zero(x)) { if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err; } else { if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err; if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err; if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err; if (!BN_GF2m_add(tmp, x, tmp)) goto err; if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) { unsigned long err = ERR_peek_last_error(); if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NO_SOLUTION) { ERR_clear_error(); ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT); } else ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB); goto err; } z0 = (BN_is_odd(z)) ? 1 : 0; if (!group->meth->field_mul(group, y, x, z, ctx)) goto err; if (z0 != y_bit) { if (!BN_GF2m_add(y, y, x)) goto err; } } if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err; ret = 1; err: BN_CTX_end(ctx); if (new_ctx != NULL) BN_CTX_free(new_ctx); return ret; #endif }