ZeroTierOne/node/Identity.cpp

302 lines
9.3 KiB
C++

/*
* 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 <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <openssl/sha.h>
#include "Identity.hpp"
#include "Salsa20.hpp"
#include "HMAC.hpp"
#include "Utils.hpp"
namespace ZeroTier {
void Identity::generate()
{
delete [] _keyPair;
// Generate key pair and derive address
do {
_keyPair = new EllipticCurveKeyPair();
_keyPair->generate();
_address = deriveAddress(_keyPair->pub().data(),_keyPair->pub().size());
} while (_address.isReserved());
_publicKey = _keyPair->pub();
// Sign address, key type, and public key with private key (with a zero
// byte between each field). Including this extra data means simply editing
// the address of an identity will be detected as its signature will be
// invalid. Of course, deep verification of address/key relationship is
// required to cover the more elaborate address claim jump attempt case.
SHA256_CTX sha;
unsigned char dig[32];
unsigned char idtype = IDENTITY_TYPE_NIST_P_521,zero = 0;
SHA256_Init(&sha);
SHA256_Update(&sha,_address.data(),ZT_ADDRESS_LENGTH);
SHA256_Update(&sha,&zero,1);
SHA256_Update(&sha,&idtype,1);
SHA256_Update(&sha,&zero,1);
SHA256_Update(&sha,_publicKey.data(),_publicKey.size());
SHA256_Update(&sha,&zero,1);
SHA256_Final(dig,&sha);
_signature = _keyPair->sign(dig);
}
bool Identity::locallyValidate(bool doAddressDerivationCheck) const
{
SHA256_CTX sha;
unsigned char dig[32];
unsigned char idtype = IDENTITY_TYPE_NIST_P_521,zero = 0;
SHA256_Init(&sha);
SHA256_Update(&sha,_address.data(),ZT_ADDRESS_LENGTH);
SHA256_Update(&sha,&zero,1);
SHA256_Update(&sha,&idtype,1);
SHA256_Update(&sha,&zero,1);
SHA256_Update(&sha,_publicKey.data(),_publicKey.size());
SHA256_Update(&sha,&zero,1);
SHA256_Final(dig,&sha);
return ((EllipticCurveKeyPair::verify(dig,_publicKey,_signature.data(),_signature.length()))&&((!doAddressDerivationCheck)||(deriveAddress(_publicKey.data(),_publicKey.size()) == _address)));
}
std::string Identity::toString(bool includePrivate) const
{
std::string r;
r.append(_address.toString());
r.append(":1:"); // 1 == IDENTITY_TYPE_NIST_P_521
r.append(Utils::base64Encode(_publicKey.data(),_publicKey.size()));
r.push_back(':');
r.append(Utils::base64Encode(_signature.data(),_signature.length()));
if ((includePrivate)&&(_keyPair)) {
r.push_back(':');
r.append(Utils::base64Encode(_keyPair->priv().data(),_keyPair->priv().size()));
}
return r;
}
bool Identity::fromString(const char *str)
{
delete _keyPair;
_keyPair = (EllipticCurveKeyPair *)0;
std::vector<std::string> fields(Utils::split(Utils::trim(std::string(str)).c_str(),":","",""));
if (fields.size() < 4)
return false;
if (fields[1] != "1")
return false; // version mismatch
std::string b(Utils::unhex(fields[0]));
if (b.length() != ZT_ADDRESS_LENGTH)
return false;
_address = b.data();
b = Utils::base64Decode(fields[2]);
if ((!b.length())||(b.length() > ZT_EC_MAX_BYTES))
return false;
_publicKey.set(b.data(),b.length());
_signature = Utils::base64Decode(fields[3]);
if (!_signature.length())
return false;
if (fields.size() >= 5) {
b = Utils::base64Decode(fields[4]);
if ((!b.length())||(b.length() > ZT_EC_MAX_BYTES))
return false;
_keyPair = new EllipticCurveKeyPair(_publicKey,EllipticCurveKey(b.data(),b.length()));
}
return true;
}
// These are core protocol parameters and can't be changed without a new
// identity type.
#define ZT_IDENTITY_DERIVEADDRESS_ROUNDS 4
#define ZT_IDENTITY_DERIVEADDRESS_MEMORY 33554432
Address Identity::deriveAddress(const void *keyBytes,unsigned int keyLen)
{
unsigned char dig[32];
Salsa20 s20a,s20b;
SHA256_CTX sha;
/*
* Sequential memory-hard algorithm wedding address to public key
*
* Conventional hashcash with long computations and quick verifications
* unfortunately cannot be used here. If that were used, it would be
* equivalently costly to simply increment/vary the public key and find
* a collision as it would be to find the address. We need something
* that creates a costly 1:~1 mapping from key to address, hence this odd
* algorithm.
*
* This is designed not to be parallelizable and to be resistant to
* implementation on things like GPUs with tiny-memory nodes and poor
* branching capability. Toward that end it throws branching and a large
* memory buffer into the mix. It can only be efficiently computed by a
* single core with at least ~32MB RAM.
*
* Search for "sequential memory hard algorithm" for academic references
* to similar concepts.
*
* Right now this takes ~1700ms on a 2.4ghz Intel Core i5. If this could
* be reduced to 1ms per derivation, it would take about 34 years to search
* the entire 40-bit address space for an average of ~17 years to generate
* a key colliding with a known existing address.
*/
// Initial starting digest
SHA256_Init(&sha);
SHA256_Update(&sha,(const unsigned char *)keyBytes,keyLen); // key
SHA256_Final(dig,&sha);
s20a.init(dig,256,"ZeroTier");
unsigned char *ram = new unsigned char[ZT_IDENTITY_DERIVEADDRESS_MEMORY];
// Encrypt and digest a large memory buffer for several rounds
for(unsigned long i=0;i<ZT_IDENTITY_DERIVEADDRESS_MEMORY;++i)
ram[i] = (unsigned char)(i & 0xff) ^ dig[i & 31];
for(unsigned long r=0;r<ZT_IDENTITY_DERIVEADDRESS_ROUNDS;++r) {
SHA256_Init(&sha);
SHA256_Update(&sha,(const unsigned char *)keyBytes,keyLen);
SHA256_Update(&sha,dig,32);
for(unsigned long i=0;i<ZT_IDENTITY_DERIVEADDRESS_MEMORY;++i) {
if (ram[i] == 17) // Forces a branch to be required
ram[i] ^= dig[i & 31];
}
s20b.init(dig,256,"ZeroTier");
s20a.encrypt(ram,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
s20b.encrypt(ram,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
SHA256_Update(&sha,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
SHA256_Final(dig,&sha);
}
// Final digest, executed for twice our number of rounds
SHA256_Init(&sha);
for(unsigned long r=0;r<(ZT_IDENTITY_DERIVEADDRESS_ROUNDS * 2);++r) {
SHA256_Update(&sha,(const unsigned char *)keyBytes,keyLen);
SHA256_Update(&sha,ram,ZT_IDENTITY_DERIVEADDRESS_ROUNDS);
SHA256_Update(&sha,dig,32);
SHA256_Update(&sha,(const unsigned char *)keyBytes,keyLen);
}
SHA256_Final(dig,&sha);
delete [] ram;
return Address(dig); // first 5 bytes of dig[]
}
std::string Identity::encrypt(const Identity &to,const void *data,unsigned int len) const
{
unsigned char key[64];
unsigned char mac[32];
unsigned char iv[8];
if (!agree(to,key,sizeof(key)))
return std::string();
Utils::getSecureRandom(iv,8);
for(int i=0;i<8;++i)
key[i + 32] ^= iv[i]; // perturb HMAC key with IV so IV is effectively included in HMAC
Salsa20 s20(key,256,iv);
std::string compressed;
compressed.reserve(len);
Utils::compress((const char *)data,(const char *)data + len,Utils::StringAppendOutput(compressed));
if (!compressed.length())
return std::string();
char *encrypted = new char[compressed.length() + 16];
try {
s20.encrypt(compressed.data(),encrypted + 16,(unsigned int)compressed.length());
HMAC::sha256(key + 32,32,encrypted + 16,(unsigned int)compressed.length(),mac);
for(int i=0;i<8;++i)
encrypted[i] = iv[i];
for(int i=0;i<8;++i)
encrypted[i + 8] = mac[i];
std::string s(encrypted,compressed.length() + 16);
delete [] encrypted;
return s;
} catch ( ... ) {
delete [] encrypted;
return std::string();
}
}
std::string Identity::decrypt(const Identity &from,const void *cdata,unsigned int len) const
{
unsigned char key[64];
unsigned char mac[32];
if (len < 16)
return std::string();
if (!agree(from,key,sizeof(key)))
return std::string();
for(int i=0;i<8;++i)
key[i + 32] ^= ((const unsigned char *)cdata)[i]; // apply IV to HMAC key
HMAC::sha256(key + 32,32,((const char *)cdata) + 16,(unsigned int)(len - 16),mac);
for(int i=0;i<8;++i) {
if (((const unsigned char *)cdata)[i + 8] != mac[i])
return std::string();
}
char *decbuf = new char[len - 16];
try {
Salsa20 s20(key,256,cdata); // first 8 bytes are IV
len -= 16;
s20.decrypt((const char *)cdata + 16,decbuf,len);
std::string decompressed;
if (Utils::decompress((const char *)decbuf,(const char *)decbuf + len,Utils::StringAppendOutput(decompressed))) {
delete [] decbuf;
return decompressed;
} else {
delete [] decbuf;
return std::string();
}
} catch ( ... ) {
delete [] decbuf;
return std::string();
}
}
} // namespace ZeroTier