1/* crypto/ec/ec2_smpt.c */ 2/* This code was originally written by Douglas Stebila 3 * <dstebila@student.math.uwaterloo.ca> for the OpenSSL project. 4 */ 5/* ==================================================================== 6 * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * openssl-core@openssl.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@cryptsoft.com). 56 * 57 */ 58 59 60/* Calaculates and sets the affine coordinates of an EC_POINT from the given 61 * compressed coordinates. Uses algorithm 2.3.4 of SEC 1. 62 * Note that the simple implementation only uses affine coordinates. 63 * 64 * This algorithm is patented by Certicom Corp. under US Patent 6,141,420 65 * (for licensing information, contact licensing@certicom.com). 66 * This function is disabled by default and can be enabled by defining the 67 * preprocessor macro OPENSSL_EC_BIN_PT_COMP at Configure-time. 68 */ 69int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point, 70 const BIGNUM *x_, int y_bit, BN_CTX *ctx) 71 { 72#ifndef OPENSSL_EC_BIN_PT_COMP 73 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_DISABLED); 74 return 0; 75#else 76 BN_CTX *new_ctx = NULL; 77 BIGNUM *tmp, *x, *y, *z; 78 int ret = 0, z0; 79 80 /* clear error queue */ 81 ERR_clear_error(); 82 83 if (ctx == NULL) 84 { 85 ctx = new_ctx = BN_CTX_new(); 86 if (ctx == NULL) 87 return 0; 88 } 89 90 y_bit = (y_bit != 0) ? 1 : 0; 91 92 BN_CTX_start(ctx); 93 tmp = BN_CTX_get(ctx); 94 x = BN_CTX_get(ctx); 95 y = BN_CTX_get(ctx); 96 z = BN_CTX_get(ctx); 97 if (z == NULL) goto err; 98 99 if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err; 100 if (BN_is_zero(x)) 101 { 102 if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err; 103 } 104 else 105 { 106 if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err; 107 if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err; 108 if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err; 109 if (!BN_GF2m_add(tmp, x, tmp)) goto err; 110 if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) 111 { 112 unsigned long err = ERR_peek_last_error(); 113 114 if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NO_SOLUTION) 115 { 116 ERR_clear_error(); 117 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT); 118 } 119 else 120 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB); 121 goto err; 122 } 123 z0 = (BN_is_odd(z)) ? 1 : 0; 124 if (!group->meth->field_mul(group, y, x, z, ctx)) goto err; 125 if (z0 != y_bit) 126 { 127 if (!BN_GF2m_add(y, y, x)) goto err; 128 } 129 } 130 131 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err; 132 133 ret = 1; 134 135 err: 136 BN_CTX_end(ctx); 137 if (new_ctx != NULL) 138 BN_CTX_free(new_ctx); 139 return ret; 140#endif 141 } 142