How to generate a fake but valid protocol hash?

Question

How do I generate a fake but valid protocol hash, like ProtoGenesisGenesisGenesisGenesisGenesisGenesk612im?

Answer 1

1. Take blake2b hash of arbitrary data.

2. Prepend \x02\xaa and base58 encode it with checksum.

Example in Python:

from pytezos.encoding import base58_encode
from pytezos.crypto import blake2b_32

base58_encode(blake2b_32('test').digest(), b'P')
>>> b'PsqEZzKWvmWY29kV6oJZhWDNz9FMmYDjV3S7c496zMuAGDYAF7e'

Answer 2

A "Tezos protocol hash" like PsqEZzKWvmWY29kV6oJZhWDNz9FMmYDjV3S7c496zMuAGDYAF7e is the Base58Check encoding of the hash of some protocol code.

The Base58Check encoding of some data is obtained as follows:

  base58encode(prefix + data + checksum)

where prefix is some fixed bytestring used to identify the type of data we are encoding, data is the bytestring we are encoding, and checksum are the last 4 bytes of SHA256(SHA256(prefix+data)) (and + is bytestring concatenation).

For a "real" protocol hash, data is the Blake2B hash (on 32 bytes) of the protocol code, and prefix is chosen such that the Base58Check encoding starts with the letter P. It turns out that this prefix is "\002\170" ("\x02\xaa"), see the Prefix submodule of the Base58 module.

A "fake" protocol hash is such that it does not represent any protocol code, instead it is just a valid Base58Check string. So data is the empty bytestring, and what we want is to find the bytestring prefix such the encoding starts with some meaningful target prefix like ProtoGenesisGenesisGenesisGenesisGenesisGenes. To this end the Python script b58_prefix.py comes to the rescue:

$ scripts/b58_prefix.py ProtoGenesisGenesisGenesisGenesisGenesisGenes 0
51 78975543388164909405054148723984031781676975010405372310033317301022658928601531 [2L, 170L, 11L, 205L, 127L, 252L, 160L, 63L, 87L, 227L, 132L, 83L, 240L, 211L, 232L, 76L, 48L, 36L, 3L, 192L, 83L, 87L, 68L, 139L, 76L, 45L, 174L, 248L, 179L, 168L, 190L, 60L, 105L, 187L]

We invoke it with the desired target prefix and the length of the payload (this is 0 as the payload is empty). The list represents the desired prefix. Finally, we just need to encode this prefix:

import base58

def tb(l):
    return b''.join(map(lambda x: x.to_bytes(1, 'big'), l))

res = base58.b58encode_check(tb([2, 170, 11, 205, 127, 252, 160, 63, 87, 227, 132, 83, 240, 211, 232, 76, 48, 36, 3, 192, 83, 87, 68, 139, 76, 45, 174, 248, 179, 168, 190, 60, 105, 187]))

print(res)

which gives us: b'ProtoGenesisGenesisGenesisGenesisGenesisGenes3pWKfA'.