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/* libanode: the Anode C reference implementation
* Copyright (C) 2009-2010 Adam Ierymenko <adam.ierymenko@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/obj_mac.h>
#include <openssl/rand.h>
#include <openssl/ec.h>
#include <openssl/ecdh.h>
#include <openssl/ecdsa.h>
#include "types.h"
#include "misc.h"
#include "ec.h"
static EC_GROUP *AnodeEC_group = (EC_GROUP *)0;
static void *AnodeEC_KDF(const void *in,size_t inlen,void *out,size_t *outlen)
{
unsigned long i,longest_length;
if (!*outlen)
return out;
for(i=0;i<(unsigned long)*outlen;++i)
((unsigned char *)out)[i] = (unsigned char)0;
longest_length = inlen;
if (longest_length < *outlen)
longest_length = *outlen;
for(i=0;i<longest_length;++i)
((unsigned char *)out)[i % (unsigned long)*outlen] ^= ((const unsigned char *)in)[i % (unsigned long)inlen];
return out;
}
int AnodeECKeyPair_generate(struct AnodeECKeyPair *pair)
{
EC_KEY *key;
int len;
#ifdef HAS_DEV_URANDOM
char buf[128];
FILE *f = fopen("/dev/urandom","r");
if (f) {
if (fread(buf,1,sizeof(buf),f) == sizeof(buf))
RAND_add(buf,sizeof(buf),sizeof(buf)/2);
fclose(f);
}
#endif
if (!AnodeEC_group) {
AnodeEC_group = EC_GROUP_new_by_curve_name(ANODE_EC_GROUP);
if (!AnodeEC_group) return 0;
}
key = EC_KEY_new();
if (!key) return 0;
if (!EC_KEY_set_group(key,AnodeEC_group)) {
EC_KEY_free(key);
return 0;
}
if (!EC_KEY_generate_key(key)) {
EC_KEY_free(key);
return 0;
}
Anode_zero(pair,sizeof(struct AnodeECKeyPair));
/* Stuff the private key into priv.key */
len = BN_num_bytes(EC_KEY_get0_private_key(key));
if ((len > ANODE_EC_PRIME_BYTES)||(len < 0)) {
EC_KEY_free(key);
return 0;
}
BN_bn2bin(EC_KEY_get0_private_key(key),&(pair->priv.key[ANODE_EC_PRIME_BYTES - len]));
pair->priv.bytes = ANODE_EC_PRIME_BYTES;
len = EC_POINT_point2oct(AnodeEC_group,EC_KEY_get0_public_key(key),POINT_CONVERSION_COMPRESSED,pair->pub.key,sizeof(pair->pub.key),0);
if (len != ANODE_EC_PUBLIC_KEY_BYTES) {
EC_KEY_free(key);
return 0;
}
pair->pub.bytes = ANODE_EC_PUBLIC_KEY_BYTES;
/* Keep a copy of OpenSSL's structure around so we don't have to re-init
* it every time we use our key pair structure. */
pair->internal_key = key;
return 1;
}
int AnodeECKeyPair_init(struct AnodeECKeyPair *pair,const struct AnodeECKey *pub,const struct AnodeECKey *priv)
{
EC_KEY *key;
EC_POINT *kxy;
BIGNUM *pn;
if (!AnodeEC_group) {
AnodeEC_group = EC_GROUP_new_by_curve_name(ANODE_EC_GROUP);
if (!AnodeEC_group) return 0;
}
key = EC_KEY_new();
if (!key)
return 0;
if (!EC_KEY_set_group(key,AnodeEC_group)) {
EC_KEY_free(key);
return 0;
}
/* Grab the private key */
if (priv->bytes != ANODE_EC_PRIME_BYTES) {
EC_KEY_free(key);
return 0;
}
pn = BN_new();
if (!pn) {
EC_KEY_free(key);
return 0;
}
if (!BN_bin2bn(priv->key,ANODE_EC_PRIME_BYTES,pn)) {
BN_free(pn);
EC_KEY_free(key);
return 0;
}
if (!EC_KEY_set_private_key(key,pn)) {
BN_free(pn);
EC_KEY_free(key);
return 0;
}
BN_free(pn);
/* Set the public key */
if (pub->bytes != ANODE_EC_PUBLIC_KEY_BYTES) {
EC_KEY_free(key);
return 0;
}
kxy = EC_POINT_new(AnodeEC_group);
if (!kxy) {
EC_KEY_free(key);
return 0;
}
EC_POINT_oct2point(AnodeEC_group,kxy,pub->key,ANODE_EC_PUBLIC_KEY_BYTES,0);
if (!EC_KEY_set_public_key(key,kxy)) {
EC_POINT_free(kxy);
EC_KEY_free(key);
return 0;
}
EC_POINT_free(kxy);
Anode_zero(pair,sizeof(struct AnodeECKeyPair));
Anode_memcpy((void *)&(pair->pub),(const void *)pub,sizeof(struct AnodeECKey));
Anode_memcpy((void *)&(pair->priv),(const void *)priv,sizeof(struct AnodeECKey));
pair->internal_key = key;
return 1;
}
void AnodeECKeyPair_destroy(struct AnodeECKeyPair *pair)
{
if (pair) {
if (pair->internal_key)
EC_KEY_free((EC_KEY *)pair->internal_key);
}
}
int AnodeECKeyPair_agree(const struct AnodeECKeyPair *my_key_pair,const struct AnodeECKey *their_pub_key,unsigned char *key_buf,unsigned int key_len)
{
EC_POINT *pub;
int i;
if (!AnodeEC_group) {
AnodeEC_group = EC_GROUP_new_by_curve_name(ANODE_EC_GROUP);
if (!AnodeEC_group) return 0;
}
if (!my_key_pair->internal_key)
return 0;
if (their_pub_key->bytes != ANODE_EC_PUBLIC_KEY_BYTES)
return 0;
pub = EC_POINT_new(AnodeEC_group);
if (!pub)
return 0;
EC_POINT_oct2point(AnodeEC_group,pub,their_pub_key->key,ANODE_EC_PUBLIC_KEY_BYTES,0);
i = ECDH_compute_key(key_buf,key_len,pub,(EC_KEY *)my_key_pair->internal_key,&AnodeEC_KDF);
if (i != (int)key_len) {
EC_POINT_free(pub);
return 0;
}
EC_POINT_free(pub);
return 1;
}
void AnodeEC_random(unsigned char *buf,unsigned int len)
{
RAND_pseudo_bytes(buf,len);
}
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