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Make new identity hashcash algo memory hard, and tweak generation time a bit. Current hashcash cost should be overkill for what we need but still tolerable to users.

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This commit is contained in:
Adam Ierymenko 2013-10-05 14:15:59 -04:00
parent a31c54b44b
commit bc715fbd51
5 changed files with 46 additions and 28 deletions
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67
node/Identity.cpp
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@ -36,39 +36,54 @@
#include "Salsa20.hpp"
#include "Utils.hpp"
// Mask for second byte in hashcash criterion -- making it require
// 13 0 bits at the start of the hash.
#define ZT_IDENTITY_SHA_BYTE1_MASK 0xf8
// 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 5
#define ZT_IDENTITY_GEN_MEMORY 8388608
namespace ZeroTier {
static inline void _computeMemoryHardHash(const void *publicKey,unsigned int publicKeyBytes,void *sha512digest)
{
unsigned char genmem[ZT_IDENTITY_GEN_MEMORY];
// Step 1: hash key to generate Salsa20 key and nonce
SHA512::hash(sha512digest,publicKey,publicKeyBytes);
// Step 2: copy key into genmen[], zero rest, encrypt with Salsa20
Salsa20 s20(sha512digest,256,((char *)sha512digest) + 32);
memcpy(genmem,publicKey,publicKeyBytes);
memset(genmem + publicKeyBytes,0,ZT_IDENTITY_GEN_MEMORY - publicKeyBytes);
s20.encrypt(genmem,genmem,ZT_IDENTITY_GEN_MEMORY);
// Step 3: hash the encrypted public key and the rest of the
// genmem[] bytes of Salsa20 key stream to yield the final hash.
SHA512::hash(sha512digest,genmem,ZT_IDENTITY_GEN_MEMORY);
}
struct _Identity_generate_cond
{
_Identity_generate_cond() throw() {}
_Identity_generate_cond(char *sb) throw() : sha512buf(sb) {}
_Identity_generate_cond(unsigned char *sb) throw() : sha512digest(sb) {}
inline bool operator()(const C25519::Pair &kp) const
throw()
{
SHA512::hash(sha512buf,kp.pub.data,kp.pub.size());
if ((!sha512buf[0])&&(!(sha512buf[1] & ZT_IDENTITY_SHA_BYTE1_MASK)))
return true;
return false;
_computeMemoryHardHash(kp.pub.data,kp.pub.size(),sha512digest);
return (sha512digest[0] < ZT_IDENTITY_GEN_HASHCASH_FIRST_BYTE_LESS_THAN);
}
char *sha512buf;
unsigned char *sha512digest;
};
void Identity::generate()
{
char sha512buf[64];
unsigned char sha512digest[64];
C25519::Pair kp;
do {
kp = C25519::generateSatisfying(_Identity_generate_cond(sha512buf));
_address.setTo(sha512buf + 59,ZT_ADDRESS_LENGTH); // last 5 bytes are address
kp = C25519::generateSatisfying(_Identity_generate_cond(sha512digest));
_address.setTo(sha512digest + 59,ZT_ADDRESS_LENGTH); // last 5 bytes are address
} while (_address.isReserved());
_publicKey = kp.pub;
@ -81,18 +96,20 @@ bool Identity::locallyValidate() const
{
if (_address.isReserved())
return false;
char sha512buf[64];
char addrb[5];
unsigned char sha512digest[64];
_computeMemoryHardHash(_publicKey.data,_publicKey.size(),sha512digest);
unsigned char addrb[5];
_address.copyTo(addrb,5);
SHA512::hash(sha512buf,_publicKey.data,_publicKey.size());
return (
(!sha512buf[0])&&
(!(sha512buf[1] & ZT_IDENTITY_SHA_BYTE1_MASK))&&
(sha512buf[59] == addrb[0])&&
(sha512buf[60] == addrb[1])&&
(sha512buf[61] == addrb[2])&&
(sha512buf[62] == addrb[3])&&
(sha512buf[63] == addrb[4]));
(sha512digest[0] < ZT_IDENTITY_GEN_HASHCASH_FIRST_BYTE_LESS_THAN)&&
(sha512digest[59] == addrb[0])&&
(sha512digest[60] == addrb[1])&&
(sha512digest[61] == addrb[2])&&
(sha512digest[62] == addrb[3])&&
(sha512digest[63] == addrb[4]));
}
std::string Identity::toString(bool includePrivate) const
@ -145,7 +162,7 @@ bool Identity::fromString(const char *str)
return false;
}
}
if (fno < 4)
if (fno < 3)
return false;
return true;