286 lines
5.9 KiB
C
286 lines
5.9 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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#ifndef NO_DH
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#include <wolfssl/wolfcrypt/dh.h>
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#include "wolfssl_diffie_hellman.h"
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#include "wolfssl_util.h"
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#include <utils/debug.h>
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typedef struct private_wolfssl_diffie_hellman_t private_wolfssl_diffie_hellman_t;
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/**
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* Private data of an wolfssl_diffie_hellman_t object.
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*/
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struct private_wolfssl_diffie_hellman_t {
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/**
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* Public wolfssl_diffie_hellman_t interface.
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*/
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wolfssl_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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* Diffie Hellman object
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*/
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DhKey dh;
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/**
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* Length of public values
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*/
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int len;
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/**
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* Private key
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*/
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chunk_t priv;
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/**
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* Public key
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*/
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chunk_t pub;
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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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METHOD(diffie_hellman_t, get_my_public_value, bool,
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private_wolfssl_diffie_hellman_t *this, chunk_t *value)
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{
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*value = chunk_copy_pad(chunk_alloc(this->len), this->pub, 0x00);
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return TRUE;
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}
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METHOD(diffie_hellman_t, get_shared_secret, bool,
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private_wolfssl_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_copy_pad(chunk_alloc(this->len), this->shared_secret, 0x00);
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return TRUE;
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}
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METHOD(diffie_hellman_t, set_other_public_value, bool,
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private_wolfssl_diffie_hellman_t *this, chunk_t value)
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{
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word32 len;
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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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chunk_clear(&this->shared_secret);
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this->shared_secret = chunk_alloc(this->len);
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if (wc_DhAgree(&this->dh, this->shared_secret.ptr, &len, this->priv.ptr,
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this->priv.len, value.ptr, value.len) != 0)
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{
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DBG1(DBG_LIB, "DH shared secret computation failed");
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chunk_free(&this->shared_secret);
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return FALSE;
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}
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this->shared_secret.len = len;
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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_wolfssl_diffie_hellman_t *this, chunk_t value)
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{
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bool success = FALSE;
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chunk_t g;
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word32 len;
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chunk_clear(&this->priv);
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this->priv = chunk_clone(value);
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/* calculate public value - g^priv mod p */
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if (wolfssl_mp2chunk(&this->dh.g, &g))
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{
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len = this->pub.len;
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if (wc_DhAgree(&this->dh, this->pub.ptr, &len, this->priv.ptr,
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this->priv.len, g.ptr, g.len) == 0)
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{
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this->pub.len = len;
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success = TRUE;
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}
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}
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free(g.ptr);
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return success;
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}
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METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
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private_wolfssl_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_wolfssl_diffie_hellman_t *this)
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{
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wc_FreeDhKey(&this->dh);
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chunk_clear(&this->pub);
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chunk_clear(&this->priv);
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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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* Maximum private key length when generating key
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*/
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static int wolfssl_priv_key_size(int len)
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{
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if (len <= 128)
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{
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return 21;
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}
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if (len <= 256)
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{
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return 29;
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}
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if (len <= 384)
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{
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return 34;
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}
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if (len <= 512)
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{
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return 39;
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}
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if (len <= 640)
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{
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return 42;
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}
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if (len <= 768)
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{
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return 46;
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}
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if (len <= 896)
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{
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return 49;
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}
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if (len <= 1024)
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{
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return 52;
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}
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return len / 20;
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}
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/**
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* Generic internal constructor
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*/
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static wolfssl_diffie_hellman_t *create_generic(diffie_hellman_group_t group,
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chunk_t g, chunk_t p)
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{
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private_wolfssl_diffie_hellman_t *this;
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word32 privLen, pubLen;
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WC_RNG rng;
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INIT(this,
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.public = {
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.dh = {
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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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},
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.group = group,
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.len = p.len,
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);
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if (wc_InitDhKey(&this->dh) != 0)
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{
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free(this);
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return NULL;
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}
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if (wc_DhSetKey(&this->dh, p.ptr, p.len, g.ptr, g.len) != 0)
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{
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destroy(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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destroy(this);
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return NULL;
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}
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this->priv = chunk_alloc(wolfssl_priv_key_size(this->len));
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this->pub = chunk_alloc(this->len);
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privLen = this->priv.len;
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pubLen = this->pub.len;
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/* generate my public and private values */
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if (wc_DhGenerateKeyPair(&this->dh, &rng, this->priv.ptr, &privLen,
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this->pub.ptr, &pubLen) != 0)
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{
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wc_FreeRng(&rng);
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destroy(this);
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return NULL;
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}
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this->pub.len = pubLen;
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this->priv.len = privLen;
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wc_FreeRng(&rng);
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return &this->public;
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}
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/*
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* Described in header
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*/
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wolfssl_diffie_hellman_t *wolfssl_diffie_hellman_create(
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diffie_hellman_group_t group, ...)
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{
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diffie_hellman_params_t *params;
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chunk_t g, p;
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if (group == MODP_CUSTOM)
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{
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VA_ARGS_GET(group, g, p);
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return create_generic(group, g, p);
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}
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params = diffie_hellman_get_params(group);
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if (!params)
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{
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return NULL;
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}
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/* wolfSSL doesn't support optimized exponent sizes according to RFC 3526 */
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return create_generic(group, params->generator, params->prime);
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}
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#endif /* NO_DH */
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