python_and_perl_bcrypt_equals.py

import base64
import bcrypt
import binascii

### This program should print 'ff00199825b2c4e1a0349eb68eac5a0dc3d485f93cb349' as well as the following perl program:
###   
###   use Crypt::Eksblowfish::Bcrypt qw(bcrypt_hash);
###   
###   my $settings = {
###       cost => 8,
###       salt => pack('H*', 'aad28123bb4983bbb6749ee462cb0e10')
###   };
###   
###   my $hash = bcrypt_hash($settings, 'a' x 72);
###   print unpack('H*', $hash);
###   

def modified_base64(data):
    normal_base64 = base64.b64encode(data).decode()
    normal_to_modified = str.maketrans('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/',
                                       './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789')
    return normal_base64.translate(normal_to_modified)

def get_salt_by_perl_salt(perl_salt_in_hex, rounds=8):
    salt = bytes.fromhex(perl_salt_in_hex)
    return '$2b$%02d$' % rounds + modified_base64(salt)[:22]

def modified_base64_decode(base64_data):
    modified_to_normal = str.maketrans('./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',
                                       'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/')
    normal_base64 = base64_data.translate(modified_to_normal)
    return base64.b64decode(normal_base64)

def extract_hex_value_from_bcrypt_hash(hash):
    tail = hash.split('$')[3] + '=='
    values = modified_base64_decode(tail[22:])
    return binascii.hexlify(values).decode()

salt = get_salt_by_perl_salt('aad28123bb4983bbb6749ee462cb0e10')
hash = bcrypt.hashpw(b'a' * 72, salt.encode()).decode()
print(extract_hex_value_from_bcrypt_hash(hash))