5ch (2ch) trip calculator snippet.

trip.py

# 5ch (2ch) trip calculator snippet

import re
import base64
import hashlib

from passlib.hash import des_crypt


DEFAULT_CHARSET = 'ms932'
TRIP_MARK = '◆'
SALT_TRANSLATOR = bytes.maketrans(rb':;<=>?@[\]^_`', b'ABCDEFGabcdef')
re_raw_trip = re.compile(
    '^#(?P<bytes>[a-zA-Z0-9]{16})(?P<salt>[a-zA-Z0-9./]{,2})$'
)


def entrip(name: str, charset: str = DEFAULT_CHARSET) -> str:
    '''
        Encrypt trip key value in handle name field to trip.
    '''
    if '#' not in name:
        return name

    prefix, tripkey = name.split('#', 1)
    tripkey = bytes(tripkey, encoding=charset)

    if len(tripkey) < 12:
        # 10 digits, normal
        salt = bytes(
            c if 0x2e <= c <= 0x7a else 0x2e for c in (tripkey + b'H.')[1:3]
        ).translate(SALT_TRANSLATOR)

        return (
            prefix + TRIP_MARK +
            des_crypt.hash(tripkey, salt=salt.decode('ascii'))[-10:]
        )

    if tripkey.startswith(b'#') or tripkey.startswith(b'$'):
        # 10 digits, raw key
        m = re_raw_trip.match(tripkey.decode(charset))

        if not m:
            # unsupported; reserved for future use
            return prefix + TRIP_MARK + '???'
        else:
            return (
                prefix + TRIP_MARK +
                des_crypt.hash(
                    bytes.fromhex(m.group('bytes')),
                    salt=(m.group('salt') + '..')[:2]
                )[-10:]
            )

    # 12 digits, normal
    return (
        prefix + TRIP_MARK +
        base64.b64encode(
            hashlib.sha1(tripkey).digest()
        )[:12].decode('ascii').replace('+', '.')
    )