oracle_padding.py 文件源码

def uncipher(cipher, key):
    cipher += '=' * (-len(cipher) % 4)
    b64_decoded = base64.urlsafe_b64decode(cipher)
    uncipher = DES.new( key, DES.MODE_CBC, b64_decoded[:8] )
    clear = uncipher.decrypt(b64_decoded)
    padding = clear[-1]
    # Check padding
    if not all(c in padding for c in clear[-ord(padding):]):
        raise PaddingError()
    return clear[8:-ord(padding)]