/* $OpenBSD: ecp_oct.c,v 1.31 2024/10/31 05:47:37 tb Exp $ */ /* Includes code written by Lenka Fibikova * for the OpenSSL project. * Includes code written by Bodo Moeller 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). * */ /* ==================================================================== * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. * Portions of this software developed by SUN MICROSYSTEMS, INC., * and contributed to the OpenSSL project. */ #include #include #include #include #include "ec_local.h" int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point, const BIGNUM *x_, int y_bit, BN_CTX *ctx) { BIGNUM *tmp1, *tmp2, *x, *y; int ret = 0; /* clear error queue */ ERR_clear_error(); y_bit = (y_bit != 0); BN_CTX_start(ctx); if ((tmp1 = BN_CTX_get(ctx)) == NULL) goto err; if ((tmp2 = BN_CTX_get(ctx)) == NULL) goto err; if ((x = BN_CTX_get(ctx)) == NULL) goto err; if ((y = BN_CTX_get(ctx)) == NULL) goto err; /* * Recover y. We have a Weierstrass equation y^2 = x^3 + a*x + b, so * y is one of the square roots of x^3 + a*x + b. */ /* tmp1 := x^3 */ if (!BN_nnmod(x, x_, &group->field, ctx)) goto err; if (group->meth->field_decode == NULL) { /* field_{sqr,mul} work on standard representation */ if (!group->meth->field_sqr(group, tmp2, x_, ctx)) goto err; if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) goto err; } else { if (!BN_mod_sqr(tmp2, x_, &group->field, ctx)) goto err; if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) goto err; } /* tmp1 := tmp1 + a*x */ if (group->a_is_minus3) { if (!BN_mod_lshift1_quick(tmp2, x, &group->field)) goto err; if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field)) goto err; if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) goto err; } else { if (group->meth->field_decode) { if (!group->meth->field_decode(group, tmp2, &group->a, ctx)) goto err; if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) goto err; } else { /* field_mul works on standard representation */ if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) goto err; } if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err; } /* tmp1 := tmp1 + b */ if (group->meth->field_decode != NULL) { if (!group->meth->field_decode(group, tmp2, &group->b, ctx)) goto err; if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err; } else { if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) goto err; } if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) { unsigned long err = ERR_peek_last_error(); if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) { ERR_clear_error(); ECerror(EC_R_INVALID_COMPRESSED_POINT); } else ECerror(ERR_R_BN_LIB); goto err; } if (y_bit != BN_is_odd(y)) { if (BN_is_zero(y)) { ECerror(EC_R_INVALID_COMPRESSION_BIT); goto err; } if (!BN_usub(y, &group->field, y)) goto err; if (y_bit != BN_is_odd(y)) { ECerror(ERR_R_INTERNAL_ERROR); goto err; } } if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx)) goto err; ret = 1; err: BN_CTX_end(ctx); return ret; }