SHA-512Half tool

sha512half.py

# Commandline tool for calculating "SHA-512Half" hashes of arbitrary strings

#!/bin/env python3

import argparse
from hashlib import sha512

p = argparse.ArgumentParser(description='Calculate SHA-512Half value.')
p.add_argument('preimage', type=str, help='String to hash')
p.add_argument('--lower', '-l', action="store_true", help='Use lowercase letters a-f')
p.add_argument("--nullprefix", "-u", action="store_true", help="Prefix with a null (\\x00) character")
    # The "null prefix" thing helps for XRP Ledger hashes which cast ASCII characters to UInt16s before hashing.
    # https://github.com/ripple/rippled/blob/c6b6d82a754fe449cc533e18659df483c10a5c98/src/ripple/protocol/impl/Indexes.cpp#L48
a = p.parse_args()

instr = a.preimage.encode("utf-8")
if a.nullprefix:
    instr = b'\x00' + instr

val = sha512(instr).hexdigest()[:64]

if a.lower:
    print(val.lower())
else:
    print(val.upper())