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403 lines
12 KiB
403 lines
12 KiB
/* crypto/ec/ec2_oct.c */ |
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/* ==================================================================== |
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* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. |
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* |
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* The Elliptic Curve Public-Key Crypto Library (ECC Code) included |
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* herein is developed by SUN MICROSYSTEMS, INC., and is contributed |
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* to the OpenSSL project. |
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* |
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* The ECC Code is licensed pursuant to the OpenSSL open source |
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* license provided below. |
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* |
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* The software is originally written by Sheueling Chang Shantz and |
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* Douglas Stebila of Sun Microsystems Laboratories. |
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* |
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*/ |
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/* ==================================================================== |
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* Copyright (c) 1998-2005 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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#include <openssl/err.h> |
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#include "ec_lcl.h" |
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#ifndef OPENSSL_NO_EC2M |
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/*- |
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* Calculates 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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* The method is from the following publication: |
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* |
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* Harper, Menezes, Vanstone: |
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* "Public-Key Cryptosystems with Very Small Key Lengths", |
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* EUROCRYPT '92, Springer-Verlag LNCS 658, |
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* published February 1993 |
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* |
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* US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe |
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* the same method, but claim no priority date earlier than July 29, 1994 |
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* (and additionally fail to cite the EUROCRYPT '92 publication as prior art). |
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*/ |
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int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, |
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EC_POINT *point, |
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const BIGNUM *x_, int y_bit, |
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BN_CTX *ctx) |
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{ |
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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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/* clear error queue */ |
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ERR_clear_error(); |
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if (ctx == NULL) { |
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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) |
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goto err; |
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if (!BN_GF2m_mod_arr(x, x_, group->poly)) |
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goto err; |
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if (BN_is_zero(x)) { |
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if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) |
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goto err; |
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} else { |
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if (!group->meth->field_sqr(group, tmp, x, ctx)) |
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goto err; |
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if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) |
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goto err; |
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if (!BN_GF2m_add(tmp, &group->a, tmp)) |
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goto err; |
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if (!BN_GF2m_add(tmp, x, tmp)) |
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goto err; |
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if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) { |
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unsigned long err = ERR_peek_last_error(); |
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if (ERR_GET_LIB(err) == ERR_LIB_BN |
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&& ERR_GET_REASON(err) == BN_R_NO_SOLUTION) { |
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ERR_clear_error(); |
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ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, |
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EC_R_INVALID_COMPRESSED_POINT); |
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} else |
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ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, |
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ERR_R_BN_LIB); |
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goto err; |
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} |
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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)) |
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goto err; |
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if (z0 != y_bit) { |
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if (!BN_GF2m_add(y, y, x)) |
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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)) |
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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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} |
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/* |
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* Converts an EC_POINT to an octet string. If buf is NULL, the encoded |
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* length will be returned. If the length len of buf is smaller than required |
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* an error will be returned. |
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*/ |
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size_t ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, |
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point_conversion_form_t form, |
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unsigned char *buf, size_t len, BN_CTX *ctx) |
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{ |
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size_t ret; |
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BN_CTX *new_ctx = NULL; |
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int used_ctx = 0; |
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BIGNUM *x, *y, *yxi; |
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size_t field_len, i, skip; |
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if ((form != POINT_CONVERSION_COMPRESSED) |
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&& (form != POINT_CONVERSION_UNCOMPRESSED) |
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&& (form != POINT_CONVERSION_HYBRID)) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM); |
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goto err; |
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} |
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if (EC_POINT_is_at_infinity(group, point)) { |
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/* encodes to a single 0 octet */ |
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if (buf != NULL) { |
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if (len < 1) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); |
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return 0; |
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} |
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buf[0] = 0; |
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} |
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return 1; |
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} |
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/* ret := required output buffer length */ |
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field_len = (EC_GROUP_get_degree(group) + 7) / 8; |
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ret = |
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(form == |
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POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; |
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/* if 'buf' is NULL, just return required length */ |
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if (buf != NULL) { |
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if (len < ret) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); |
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goto err; |
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} |
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if (ctx == NULL) { |
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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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BN_CTX_start(ctx); |
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used_ctx = 1; |
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x = BN_CTX_get(ctx); |
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y = BN_CTX_get(ctx); |
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yxi = BN_CTX_get(ctx); |
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if (yxi == NULL) |
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goto err; |
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if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx)) |
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goto err; |
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buf[0] = form; |
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if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) { |
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if (!group->meth->field_div(group, yxi, y, x, ctx)) |
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goto err; |
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if (BN_is_odd(yxi)) |
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buf[0]++; |
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} |
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i = 1; |
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skip = field_len - BN_num_bytes(x); |
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if (skip > field_len) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
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goto err; |
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} |
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while (skip > 0) { |
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buf[i++] = 0; |
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skip--; |
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} |
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skip = BN_bn2bin(x, buf + i); |
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i += skip; |
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if (i != 1 + field_len) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
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goto err; |
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} |
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if (form == POINT_CONVERSION_UNCOMPRESSED |
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|| form == POINT_CONVERSION_HYBRID) { |
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skip = field_len - BN_num_bytes(y); |
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if (skip > field_len) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
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goto err; |
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} |
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while (skip > 0) { |
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buf[i++] = 0; |
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skip--; |
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} |
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skip = BN_bn2bin(y, buf + i); |
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i += skip; |
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} |
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if (i != ret) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
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goto err; |
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} |
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} |
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if (used_ctx) |
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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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err: |
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if (used_ctx) |
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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 0; |
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} |
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/* |
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* Converts an octet string representation to an EC_POINT. Note that the |
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* simple implementation only uses affine coordinates. |
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*/ |
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int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point, |
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const unsigned char *buf, size_t len, |
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BN_CTX *ctx) |
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{ |
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point_conversion_form_t form; |
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int y_bit; |
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BN_CTX *new_ctx = NULL; |
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BIGNUM *x, *y, *yxi; |
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size_t field_len, enc_len; |
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int ret = 0; |
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if (len == 0) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL); |
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return 0; |
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} |
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form = buf[0]; |
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y_bit = form & 1; |
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form = form & ~1U; |
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if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) |
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&& (form != POINT_CONVERSION_UNCOMPRESSED) |
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&& (form != POINT_CONVERSION_HYBRID)) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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return 0; |
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} |
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if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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return 0; |
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} |
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if (form == 0) { |
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if (len != 1) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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return 0; |
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} |
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return EC_POINT_set_to_infinity(group, point); |
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} |
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field_len = (EC_GROUP_get_degree(group) + 7) / 8; |
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enc_len = |
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(form == |
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POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; |
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if (len != enc_len) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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return 0; |
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} |
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if (ctx == NULL) { |
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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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BN_CTX_start(ctx); |
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x = BN_CTX_get(ctx); |
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y = BN_CTX_get(ctx); |
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yxi = BN_CTX_get(ctx); |
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if (yxi == NULL) |
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goto err; |
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if (!BN_bin2bn(buf + 1, field_len, x)) |
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goto err; |
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if (BN_ucmp(x, &group->field) >= 0) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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goto err; |
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} |
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if (form == POINT_CONVERSION_COMPRESSED) { |
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if (!EC_POINT_set_compressed_coordinates_GF2m |
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(group, point, x, y_bit, ctx)) |
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goto err; |
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} else { |
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if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) |
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goto err; |
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if (BN_ucmp(y, &group->field) >= 0) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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goto err; |
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} |
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if (form == POINT_CONVERSION_HYBRID) { |
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if (!group->meth->field_div(group, yxi, y, x, ctx)) |
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goto err; |
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if (y_bit != BN_is_odd(yxi)) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
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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)) |
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goto err; |
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} |
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/* test required by X9.62 */ |
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if (EC_POINT_is_on_curve(group, point, ctx) <= 0) { |
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ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE); |
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goto err; |
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} |
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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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} |
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#endif
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