232 lines
5.4 KiB
C
232 lines
5.4 KiB
C
/*
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* Copyright (C) 2019 Sean Parkinson, wolfSSL Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "wolfssl_common.h"
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#ifdef HAVE_CURVE25519
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#include "wolfssl_x_diffie_hellman.h"
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#include <utils/debug.h>
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#include <wolfssl/wolfcrypt/curve25519.h>
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#include <wolfssl/wolfcrypt/fe_operations.h>
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typedef struct private_diffie_hellman_t private_diffie_hellman_t;
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/**
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* Private data
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*/
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struct private_diffie_hellman_t {
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/**
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* Public interface.
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*/
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diffie_hellman_t public;
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/**
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* Diffie Hellman group number.
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*/
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diffie_hellman_group_t group;
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/**
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* Private (public) key
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*/
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curve25519_key key;
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/**
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* Shared secret
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*/
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chunk_t shared_secret;
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};
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/**
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* Compute the shared secret
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*/
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static bool compute_shared_key(private_diffie_hellman_t *this,
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curve25519_key *pub, chunk_t *shared_secret)
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{
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word32 len = CURVE25519_KEYSIZE;
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int ret;
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*shared_secret = chunk_alloc(len);
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ret = wc_curve25519_shared_secret_ex(&this->key, pub, shared_secret->ptr,
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&len, EC25519_LITTLE_ENDIAN);
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return ret == 0;
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}
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METHOD(diffie_hellman_t, set_other_public_value, bool,
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private_diffie_hellman_t *this, chunk_t value)
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{
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curve25519_key pub;
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int ret;
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if (!diffie_hellman_verify_value(this->group, value))
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{
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return FALSE;
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}
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ret = wc_curve25519_init(&pub);
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if (ret != 0)
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{
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DBG1(DBG_LIB, "%N public key initialization failed",
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diffie_hellman_group_names, this->group);
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return FALSE;
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}
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ret = wc_curve25519_import_public_ex(value.ptr, value.len, &pub,
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EC25519_LITTLE_ENDIAN);
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if (ret != 0)
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{
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DBG1(DBG_LIB, "%N public value is malformed",
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diffie_hellman_group_names, this->group);
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return FALSE;
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}
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chunk_clear(&this->shared_secret);
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if (!compute_shared_key(this, &pub, &this->shared_secret))
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{
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DBG1(DBG_LIB, "%N shared secret computation failed",
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diffie_hellman_group_names, this->group);
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chunk_clear(&this->shared_secret);
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wc_curve25519_free(&pub);
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return FALSE;
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}
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wc_curve25519_free(&pub);
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return TRUE;
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}
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METHOD(diffie_hellman_t, get_my_public_value, bool,
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private_diffie_hellman_t *this, chunk_t *value)
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{
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word32 len = CURVE25519_KEYSIZE;
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*value = chunk_alloc(len);
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if (wc_curve25519_export_public_ex(&this->key, value->ptr, &len,
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EC25519_LITTLE_ENDIAN) != 0)
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{
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chunk_free(value);
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return FALSE;
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}
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return TRUE;
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}
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METHOD(diffie_hellman_t, set_private_value, bool,
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private_diffie_hellman_t *this, chunk_t value)
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{
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curve25519_key pub;
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u_char basepoint[CURVE25519_KEYSIZE] = {9};
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word32 len = CURVE25519_KEYSIZE;
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int ret;
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ret = wc_curve25519_init(&pub);
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/* create base point for calculating public key */
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if (ret == 0)
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{
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ret = wc_curve25519_import_public_ex(basepoint, CURVE25519_KEYSIZE,
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&pub, EC25519_LITTLE_ENDIAN);
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}
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if (ret == 0)
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{
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ret = wc_curve25519_import_private_ex(value.ptr, value.len, &this->key,
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EC25519_LITTLE_ENDIAN);
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}
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if (ret == 0)
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{
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ret = wc_curve25519_shared_secret_ex(&this->key, &pub,
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this->key.p.point, &len, EC25519_LITTLE_ENDIAN);
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}
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return ret == 0;
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}
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METHOD(diffie_hellman_t, get_shared_secret, bool,
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private_diffie_hellman_t *this, chunk_t *secret)
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{
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if (!this->shared_secret.len)
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{
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return FALSE;
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}
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*secret = chunk_clone(this->shared_secret);
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return TRUE;
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}
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METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
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private_diffie_hellman_t *this)
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{
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return this->group;
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}
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METHOD(diffie_hellman_t, destroy, void,
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private_diffie_hellman_t *this)
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{
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wc_curve25519_free(&this->key);
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chunk_clear(&this->shared_secret);
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free(this);
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}
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/*
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* Described in header
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*/
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diffie_hellman_t *wolfssl_x_diffie_hellman_create(diffie_hellman_group_t group)
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{
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private_diffie_hellman_t *this;
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WC_RNG rng;
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int ret;
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INIT(this,
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.public = {
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.get_shared_secret = _get_shared_secret,
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.set_other_public_value = _set_other_public_value,
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.get_my_public_value = _get_my_public_value,
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.set_private_value = _set_private_value,
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.get_dh_group = _get_dh_group,
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.destroy = _destroy,
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},
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.group = group,
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);
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if (wc_curve25519_init(&this->key) != 0)
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{
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DBG1(DBG_LIB, "initializing key failed");
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free(this);
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return NULL;
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}
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if (wc_InitRng(&rng) != 0)
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{
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DBG1(DBG_LIB, "initializing a random number generator failed");
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destroy(this);
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return NULL;
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}
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ret = wc_curve25519_make_key(&rng, CURVE25519_KEYSIZE, &this->key);
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wc_FreeRng(&rng);
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if (ret != 0)
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{
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DBG1(DBG_LIB, "making a key failed");
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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#endif /* HAVE_CURVE25519 */
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