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Hashcash-based identity, work in progress... committing to test speed on other boxes.

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This commit is contained in:
Adam Ierymenko 2013-10-05 06:00:47 -04:00
parent 588a47be89
commit b0187f4472
6 changed files with 51 additions and 114 deletions
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118
node/Identity.cpp
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@ -34,37 +34,50 @@
#include "Identity.hpp"
#include "SHA512.hpp"
#include "Salsa20.hpp"
#include "Utils.hpp"
namespace ZeroTier {
/*
* This is the hashcash criterion
*/
struct _Identity_generate_cond
{
_Identity_generate_cond() throw() {}
_Identity_generate_cond(char *sb) throw() : sha512buf(sb) {}
inline bool operator()(const C25519::Pair &kp) const
throw()
{
SHA512::hash(sha512buf,kp.pub.data,kp.pub.size());
if ((!sha512buf[0])&&(!(sha512buf[1] & 0xf0)))
return true;
return false;
}
char *sha512buf;
};
void Identity::generate()
{
char sha512buf[64];
C25519::Pair kp;
do {
kp = C25519::generate();
_address = deriveAddress(kp.pub.data,kp.pub.size());
kp = C25519::generateSatisfying(_Identity_generate_cond(sha512buf));
_address.setTo(sha512buf + 59,ZT_ADDRESS_LENGTH); // last 5 bytes are address
} while (_address.isReserved());
_publicKey = kp.pub;
if (!_privateKey)
_privateKey = new C25519::Private();
*_privateKey = kp.priv;
unsigned char tmp[ZT_ADDRESS_LENGTH + ZT_C25519_PUBLIC_KEY_LEN];
_address.copyTo(tmp,ZT_ADDRESS_LENGTH);
memcpy(tmp + ZT_ADDRESS_LENGTH,_publicKey.data,ZT_C25519_PUBLIC_KEY_LEN);
_signature = C25519::sign(kp,tmp,sizeof(tmp));
}
bool Identity::locallyValidate(bool doAddressDerivationCheck) const
{
unsigned char tmp[ZT_ADDRESS_LENGTH + ZT_C25519_PUBLIC_KEY_LEN];
_address.copyTo(tmp,ZT_ADDRESS_LENGTH);
memcpy(tmp + ZT_ADDRESS_LENGTH,_publicKey.data,ZT_C25519_PUBLIC_KEY_LEN);
if (!C25519::verify(_publicKey,tmp,sizeof(tmp),_signature))
return false;
if ((doAddressDerivationCheck)&&(deriveAddress(_publicKey.data,_publicKey.size()) != _address))
return false;
return true;
}
@ -73,10 +86,8 @@ std::string Identity::toString(bool includePrivate) const
std::string r;
r.append(_address.toString());
r.append(":2:"); // 2 == IDENTITY_TYPE_C25519
r.append(":0:"); // 0 == IDENTITY_TYPE_C25519
r.append(Utils::hex(_publicKey.data,_publicKey.size()));
r.push_back(':');
r.append(Utils::hex(_signature.data,_signature.size()));
if ((_privateKey)&&(includePrivate)) {
r.push_back(':');
r.append(Utils::hex(_privateKey->data,_privateKey->size()));
@ -104,7 +115,7 @@ bool Identity::fromString(const char *str)
return false;
break;
case 1:
if (strcmp(f,"2"))
if (f[0] != '0')
return false;
break;
case 2:
@ -112,10 +123,6 @@ bool Identity::fromString(const char *str)
return false;
break;
case 3:
if (Utils::unhex(f,_signature.data,_signature.size()) != _signature.size())
return false;
break;
case 4:
_privateKey = new C25519::Private();
if (Utils::unhex(f,_privateKey->data,_privateKey->size()) != _privateKey->size())
return false;
@ -130,72 +137,5 @@ bool Identity::fromString(const char *str)
return true;
}
// These are fixed parameters and can't be changed without a new
// identity type.
#define ZT_IDENTITY_DERIVEADDRESS_MEMORY 33554432
#define ZT_IDENTITY_DERIVEADDRESS_ROUNDS 50
Address Identity::deriveAddress(const void *keyBytes,unsigned int keyLen)
{
/*
* 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
* algorithm.
*
* Search for "sequential memory hard algorithm" for academic references
* to similar concepts.
*/
unsigned char *ram = new unsigned char[ZT_IDENTITY_DERIVEADDRESS_MEMORY];
for(unsigned int i=0;i<ZT_IDENTITY_DERIVEADDRESS_MEMORY;++i)
ram[i] = ((const unsigned char *)keyBytes)[i % keyLen];
unsigned char salsaKey[ZT_SHA512_DIGEST_LEN];
SHA512::hash(salsaKey,keyBytes,keyLen);
uint64_t nonce = 0;
for(unsigned int r=0;r<ZT_IDENTITY_DERIVEADDRESS_ROUNDS;++r) {
nonce = Utils::crc64(nonce,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
#if __BYTE_ORDER == __BIG_ENDIAN
nonce = ( // swap to little endian -- this was written for a LE system
((nonce & 0x00000000000000FFULL) << 56) |
((nonce & 0x000000000000FF00ULL) << 40) |
((nonce & 0x0000000000FF0000ULL) << 24) |
((nonce & 0x00000000FF000000ULL) << 8) |
((nonce & 0x000000FF00000000ULL) >> 8) |
((nonce & 0x0000FF0000000000ULL) >> 24) |
((nonce & 0x00FF000000000000ULL) >> 40) |
((nonce & 0xFF00000000000000ULL) >> 56)
);
#endif
Salsa20 s20(salsaKey,256,&nonce);
#if __BYTE_ORDER == __BIG_ENDIAN
nonce = ( // swap back to big endian
((nonce & 0x00000000000000FFULL) << 56) |
((nonce & 0x000000000000FF00ULL) << 40) |
((nonce & 0x0000000000FF0000ULL) << 24) |
((nonce & 0x00000000FF000000ULL) << 8) |
((nonce & 0x000000FF00000000ULL) >> 8) |
((nonce & 0x0000FF0000000000ULL) >> 24) |
((nonce & 0x00FF000000000000ULL) >> 40) |
((nonce & 0xFF00000000000000ULL) >> 56)
);
#endif
s20.encrypt(ram,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
}
unsigned char finalDigest[ZT_SHA512_DIGEST_LEN];
SHA512::hash(finalDigest,ram,ZT_IDENTITY_DERIVEADDRESS_MEMORY);
delete [] ram;
return Address(finalDigest,ZT_ADDRESS_LENGTH);
}
} // namespace ZeroTier