"""
module for creating frames of data that can be sent to a YubiKey
"""
# Copyright (c) 2010, Yubico AB
# See the file COPYING for licence statement.
__all__ = [
# constants
# functions
# classes
'YubiKeyFrame',
]
import struct
from . import yubico_util
from . import yubikey_defs
from . import yubico_exception
from .yubico_version import __version__
from .yubikey_defs import SLOT
class YubiKeyFrame:
"""
Class containing an YKFRAME (as defined in ykdef.h).
A frame is basically 64 bytes of data. When this is to be sent
to a YubiKey, it is put inside 10 USB HID feature reports. Each
feature report is 7 bytes of data plus 1 byte of sequencing and
flags.
"""
def __init__(self, command, payload=b''):
if not payload:
payload = b'\x00' * 64
if len(payload) != 64:
raise yubico_exception.InputError('payload must be empty or 64 bytes')
if not isinstance(payload, bytes):
raise yubico_exception.InputError('payload must be a bytestring')
self.payload = payload
self.command = command
self.crc = yubico_util.crc16(payload)
def __repr__(self):
return '<%s.%s instance at %s: %s>' % (
self.__class__.__module__,
self.__class__.__name__,
hex(id(self)),
self.command
)
def to_string(self):
"""
Return the frame as a 70 byte string.
"""
# From ykdef.h :
#
# // Frame structure
# #define SLOT_DATA_SIZE 64
# typedef struct {
# unsigned char payload[SLOT_DATA_SIZE];
# unsigned char slot;
# unsigned short crc;
# unsigned char filler[3];
# } YKFRAME;
filler = b''
return struct.pack('<64sBH3s',
self.payload, self.command, self.crc, filler)
def to_feature_reports(self, debug=False):
"""
Return the frame as an array of 8-byte parts, ready to be sent to a YubiKey.
"""
rest = self.to_string()
seq = 0
out = []
# When sending a frame to the YubiKey, we can (should) remove any
# 7-byte serie that only consists of '\x00', besides the first
# and last serie.
while rest:
this, rest = rest[:7], rest[7:]
if seq > 0 and rest:
# never skip first or last serie
if this != b'\x00\x00\x00\x00\x00\x00\x00':
this += yubico_util.chr_byte(yubikey_defs.SLOT_WRITE_FLAG + seq)
out.append(self._debug_string(debug, this))
else:
this += yubico_util.chr_byte(yubikey_defs.SLOT_WRITE_FLAG + seq)
out.append(self._debug_string(debug, this))
seq += 1
return out
def _debug_string(self, debug, data):
"""
Annotate a frames data, if debug is True.
"""
if not debug:
return data
if self.command in [
SLOT.CONFIG,
SLOT.CONFIG2,
SLOT.UPDATE1,
SLOT.UPDATE2,
SLOT.SWAP,
]:
# annotate according to config_st (see ykdef.h)
if yubico_util.ord_byte(data[-1]) == 0x80:
return (data, "FFFFFFF") # F = Fixed data (16 bytes)
if yubico_util.ord_byte(data[-1]) == 0x81:
return (data, "FFFFFFF")
if yubico_util.ord_byte(data[-1]) == 0x82:
return (data, "FFUUUUU") # U = UID (6 bytes)
if yubico_util.ord_byte(data[-1]) == 0x83:
return (data, "UKKKKKK") # K = Key (16 bytes)
if yubico_util.ord_byte(data[-1]) == 0x84:
return (data, "KKKKKKK")
if yubico_util.ord_byte(data[-1]) == 0x85:
return (data, "KKKAAAA") # A = Access code to set (6 bytes)
if yubico_util.ord_byte(data[-1]) == 0x86:
return (data, "AAlETCr") # l = Length of fixed field (1 byte)
# E = extFlags (1 byte)
# T = tktFlags (1 byte)
# C = cfgFlags (1 byte)
# r = RFU (2 bytes)
if yubico_util.ord_byte(data[-1]) == 0x87:
return (data, "rCRaaaa") # CR = CRC16 checksum (2 bytes)
# a = Access code to use (6 bytes)
if yubico_util.ord_byte(data[-1]) == 0x88:
return (data, 'aa')
# after payload
if yubico_util.ord_byte(data[-1]) == 0x89:
return (data, " Scr")
return (data, '')