mirror of
https://github.com/openssl/openssl.git
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1212818eb0
Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7176)
367 lines
10 KiB
C
367 lines
10 KiB
C
/*
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* Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
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* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <openssl/err.h>
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#include <openssl/symhacks.h>
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#include "ec_lcl.h"
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int ec_GFp_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 *tmp1, *tmp2, *x, *y;
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int ret = 0;
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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);
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BN_CTX_start(ctx);
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tmp1 = BN_CTX_get(ctx);
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tmp2 = 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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if (y == NULL)
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goto err;
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/*-
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* Recover y. We have a Weierstrass equation
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* y^2 = x^3 + a*x + b,
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* so y is one of the square roots of x^3 + a*x + b.
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*/
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/* tmp1 := x^3 */
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if (!BN_nnmod(x, x_, group->field, ctx))
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goto err;
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if (group->meth->field_decode == 0) {
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/* field_{sqr,mul} work on standard representation */
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if (!group->meth->field_sqr(group, tmp2, x_, ctx))
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goto err;
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if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx))
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goto err;
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} else {
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if (!BN_mod_sqr(tmp2, x_, group->field, ctx))
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goto err;
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if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx))
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goto err;
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}
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/* tmp1 := tmp1 + a*x */
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if (group->a_is_minus3) {
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if (!BN_mod_lshift1_quick(tmp2, x, group->field))
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goto err;
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if (!BN_mod_add_quick(tmp2, tmp2, x, group->field))
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goto err;
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if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field))
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goto err;
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} else {
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if (group->meth->field_decode) {
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if (!group->meth->field_decode(group, tmp2, group->a, ctx))
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goto err;
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if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx))
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goto err;
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} else {
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/* field_mul works on standard representation */
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if (!group->meth->field_mul(group, tmp2, group->a, x, ctx))
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goto err;
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}
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if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
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goto err;
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}
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/* tmp1 := tmp1 + b */
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if (group->meth->field_decode) {
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if (!group->meth->field_decode(group, tmp2, group->b, ctx))
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goto err;
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if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field))
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goto err;
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} else {
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if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field))
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goto err;
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}
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if (!BN_mod_sqrt(y, tmp1, group->field, 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_NOT_A_SQUARE) {
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ERR_clear_error();
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ECerr(EC_F_EC_GFP_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_GFP_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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if (y_bit != BN_is_odd(y)) {
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if (BN_is_zero(y)) {
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int kron;
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kron = BN_kronecker(x, group->field, ctx);
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if (kron == -2)
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goto err;
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if (kron == 1)
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ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
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EC_R_INVALID_COMPRESSION_BIT);
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else
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/*
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* BN_mod_sqrt() should have caught this error (not a square)
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*/
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ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
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EC_R_INVALID_COMPRESSED_POINT);
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goto err;
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}
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if (!BN_usub(y, group->field, y))
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goto err;
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}
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if (y_bit != BN_is_odd(y)) {
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ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES,
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ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if (!EC_POINT_set_affine_coordinates(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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BN_CTX_free(new_ctx);
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return ret;
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}
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size_t ec_GFp_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;
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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_GFP_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_GFP_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 = BN_num_bytes(group->field);
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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_GFP_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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if (y == NULL)
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goto err;
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if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
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goto err;
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if ((form == POINT_CONVERSION_COMPRESSED
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|| form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
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buf[0] = form + 1;
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else
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buf[0] = form;
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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_GFP_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_GFP_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_GFP_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_GFP_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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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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BN_CTX_free(new_ctx);
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return 0;
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}
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int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
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const unsigned char *buf, size_t len, 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;
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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_GFP_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_GFP_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_GFP_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_GFP_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 = BN_num_bytes(group->field);
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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_GFP_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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if (y == 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_GFP_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(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_GFP_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 (y_bit != BN_is_odd(y)) {
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ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
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goto err;
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}
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}
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/*
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* EC_POINT_set_affine_coordinates is responsible for checking that
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* the point is on the curve.
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*/
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if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
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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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BN_CTX_free(new_ctx);
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return ret;
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}
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