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/*
* ZeroTier One - Global Peer to Peer Ethernet
* Copyright (C) 2012-2013 ZeroTier Networks LLC
*
* 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/>.
*
* --
*
* ZeroTier may be used and distributed under the terms of the GPLv3, which
* are available at: http://www.gnu.org/licenses/gpl-3.0.html
*
* If you would like to embed ZeroTier into a commercial application or
* redistribute it in a modified binary form, please contact ZeroTier Networks
* LLC. Start here: http://www.zerotier.com/
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "Constants.hpp"
#include "Identity.hpp"
#include "SHA512.hpp"
#include "Salsa20.hpp"
#include "Utils.hpp"
// These can't be changed without a new identity type. They define the
// parameters of the hashcash hashing/searching algorithm.
#define ZT_IDENTITY_GEN_HASHCASH_FIRST_BYTE_LESS_THAN 17
#define ZT_IDENTITY_GEN_MEMORY 2097152
#define ZT_IDENTITY_GEN_SALSA20_ROUNDS 20
namespace ZeroTier {
// A memory-hard composition of SHA-512 and Salsa20 for hashcash hashing
static inline void _computeMemoryHardHash(const void *publicKey,unsigned int publicKeyBytes,void *digest,void *genmem)
{
// Digest publicKey[] to obtain initial digest
SHA512::hash(digest,publicKey,publicKeyBytes);
// Initialize genmem[] using Salsa20 in a CBC-like configuration since
// ordinary Salsa20 is randomly seekable. This is good for a cipher
// but is not what we want for sequential memory-harndess.
memset(genmem,0,ZT_IDENTITY_GEN_MEMORY);
Salsa20 s20(digest,256,(char *)digest + 32,ZT_IDENTITY_GEN_SALSA20_ROUNDS);
s20.encrypt((char *)genmem,(char *)genmem,64);
for(unsigned long i=64;i<ZT_IDENTITY_GEN_MEMORY;i+=64) {
unsigned long k = i - 64;
*((uint64_t *)((char *)genmem + i)) = *((uint64_t *)((char *)genmem + k));
*((uint64_t *)((char *)genmem + i + 8)) = *((uint64_t *)((char *)genmem + k + 8));
*((uint64_t *)((char *)genmem + i + 16)) = *((uint64_t *)((char *)genmem + k + 16));
*((uint64_t *)((char *)genmem + i + 24)) = *((uint64_t *)((char *)genmem + k + 24));
*((uint64_t *)((char *)genmem + i + 32)) = *((uint64_t *)((char *)genmem + k + 32));
*((uint64_t *)((char *)genmem + i + 40)) = *((uint64_t *)((char *)genmem + k + 40));
*((uint64_t *)((char *)genmem + i + 48)) = *((uint64_t *)((char *)genmem + k + 48));
*((uint64_t *)((char *)genmem + i + 56)) = *((uint64_t *)((char *)genmem + k + 56));
s20.encrypt((char *)genmem + i,(char *)genmem + i,64);
}
// Render final digest using genmem as a lookup table
for(unsigned long i=0;i<(ZT_IDENTITY_GEN_MEMORY / sizeof(uint64_t));) {
unsigned long idx1 = (unsigned long)(Utils::ntoh(((uint64_t *)genmem)[i++]) % (64 / sizeof(uint64_t)));
unsigned long idx2 = (unsigned long)(Utils::ntoh(((uint64_t *)genmem)[i++]) % (ZT_IDENTITY_GEN_MEMORY / sizeof(uint64_t)));
uint64_t tmp = ((uint64_t *)genmem)[idx2];
((uint64_t *)genmem)[idx2] = ((uint64_t *)digest)[idx1];
((uint64_t *)digest)[idx1] = tmp;
s20.encrypt(digest,digest,64);
}
}
// Hashcash generation halting condition -- halt when first byte is less than
// threshold value.
struct _Identity_generate_cond
{
_Identity_generate_cond() throw() {}
_Identity_generate_cond(unsigned char *sb,char *gm) throw() : digest(sb),genmem(gm) {}
inline bool operator()(const C25519::Pair &kp) const
throw()
{
_computeMemoryHardHash(kp.pub.data,(unsigned int)kp.pub.size(),digest,genmem);
return (digest[0] < ZT_IDENTITY_GEN_HASHCASH_FIRST_BYTE_LESS_THAN);
}
unsigned char *digest;
char *genmem;
};
void Identity::generate()
{
unsigned char digest[64];
char *genmem = new char[ZT_IDENTITY_GEN_MEMORY];
C25519::Pair kp;
do {
kp = C25519::generateSatisfying(_Identity_generate_cond(digest,genmem));
_address.setTo(digest + 59,ZT_ADDRESS_LENGTH); // last 5 bytes are address
} while (_address.isReserved());
_publicKey = kp.pub;
if (!_privateKey)
_privateKey = new C25519::Private();
*_privateKey = kp.priv;
delete [] genmem;
}
bool Identity::locallyValidate() const
{
if (_address.isReserved())
return false;
unsigned char digest[64];
char *genmem = new char[ZT_IDENTITY_GEN_MEMORY];
_computeMemoryHardHash(_publicKey.data,(unsigned int)_publicKey.size(),digest,genmem);
delete [] genmem;
unsigned char addrb[5];
_address.copyTo(addrb,5);
return (
(digest[0] < ZT_IDENTITY_GEN_HASHCASH_FIRST_BYTE_LESS_THAN)&&
(digest[59] == addrb[0])&&
(digest[60] == addrb[1])&&
(digest[61] == addrb[2])&&
(digest[62] == addrb[3])&&
(digest[63] == addrb[4]));
}
std::string Identity::toString(bool includePrivate) const
{
std::string r;
r.append(_address.toString());
r.append(":0:"); // 0 == IDENTITY_TYPE_C25519
r.append(Utils::hex(_publicKey.data,(unsigned int)_publicKey.size()));
if ((_privateKey)&&(includePrivate)) {
r.push_back(':');
r.append(Utils::hex(_privateKey->data,(unsigned int)_privateKey->size()));
}
return r;
}
bool Identity::fromString(const char *str)
{
char *saveptr = (char *)0;
char tmp[4096];
if (!Utils::scopy(tmp,sizeof(tmp),str))
return false;
delete _privateKey;
_privateKey = (C25519::Private *)0;
int fno = 0;
for(char *f=Utils::stok(tmp,":",&saveptr);(f);f=Utils::stok((char *)0,":",&saveptr)) {
switch(fno++) {
case 0:
_address = Address(f);
if (_address.isReserved())
return false;
break;
case 1:
if ((f[0] != '0')||(f[1]))
return false;
break;
case 2:
if (Utils::unhex(f,_publicKey.data,(unsigned int)_publicKey.size()) != _publicKey.size())
return false;
break;
case 3:
_privateKey = new C25519::Private();
if (Utils::unhex(f,_privateKey->data,(unsigned int)_privateKey->size()) != _privateKey->size())
return false;
break;
default:
return false;
}
}
if (fno < 3)
return false;
return true;
}
} // namespace ZeroTier
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