btcr2john.py

#!/usr/bin/env python

from base64 import *
import sys, struct, zlib

print >> sys.stderr, 'btcrecover extract> ',
key_crc_data = b64decode(raw_input())
key_data = key_crc_data[:-4]
assert key_data[:3] == 'bc:'

# Check the CRC
(key_crc,) = struct.unpack('<I', key_crc_data[-4:])
assert zlib.crc32(key_data) & 0xffffffff == key_crc

mkey, salt, iter_count = struct.unpack('< 32s 8s I', key_data[3:])

print >> sys.stderr, 'John the Ripper compatible, Hashcat compatible, or both (j/h/b)? ',
choice = raw_input()[0].lower()
if choice != 'h':
    mkey = 16 * '\0' + mkey

hash = '$bitcoin${}${}$16${}${}$0$$'.format(len(mkey)*2, b16encode(mkey).lower(), b16encode(salt).lower(), iter_count)

if choice == 'j':
    pad_len = 2
else:
    # From hashcat:
    DISPLAY_LEN_MIN_11300 = 1 + 7 + 1 + 2 + 1 + 96 + 1 + 2 + 1 + 16 + 1 + 1 + 1 + 2 + 1 + 96 + 1 + 1 + 1 + 2
    pad_len = DISPLAY_LEN_MIN_11300 - len(hash) - 2
    assert pad_len > 0
    pad_len += pad_len & 1  # round up to even

hash += '{}${}'.format(pad_len, pad_len * '0')
print hash