test_tripledeskw.doctest - test keywrap functions

Copyright (C) 2014-2016 Arthur de Jong

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modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

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but WITHOUT ANY WARRANTY; without even the implied warranty of
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>>> import re
>>> from binascii import a2b_hex
>>> from pskc.crypto.tripledeskw import wrap, unwrap
>>> def fromhex(value):
...     return a2b_hex(re.sub(r'\s', '', value))


Example from RFC 3217 section 3.2 wrapping a 192 bit Triple DES key with
another 192 bit Triple DES key.

>>> plaintext = fromhex('''
... 2923 bf85 e06d d6ae 5291 49f1 f1ba e9ea b3a7 da3d 860d 3e98
... ''')
>>> key = fromhex('''
... 255e 0d1c 07b6 46df b313 4cc8 43ba 8aa7 1f02 5b7c 0838 251f
... ''')
>>> iv = fromhex('5dd4 cbfc 96f5 453b')
>>> ciphertext = fromhex('''
... 6901 0761 8ef0 92b3 b48c a179 6b23 4ae9 fa33 ebb4 1596 0403
... 7db5 d6a8 4eb3 aac2 768c 6327 75a4 67d4
... ''')
>>> wrap(plaintext, key, iv=iv) == ciphertext
True
>>> unwrap(ciphertext, key) == plaintext
True


Leaving out the iv ensures that a random iv is used.

>>> c = wrap(plaintext, key)
>>> c == ciphertext
False
>>> unwrap(c, key) == plaintext
True


Wrapping is only specified for Triple DES keys but the algorithms works for
any plaintext that is a multiple of the Triple DES block size but fails
otherwise.

>>> short_plaintext = fromhex('''
... 2923 bf85 e06d d6ae 5291 49f1 f1ba e9ea
... ''')
>>> unwrap(wrap(short_plaintext, key), key) == short_plaintext
True
>>> short_plaintext = fromhex('''
... 2923 bf85 e06d d6ae 5291 49f1 f1ba e9
... ''')
>>> wrap(short_plaintext, key)  # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
    ...
EncryptionError: Plaintext length wrong


The ciphertext must have the correct length (multiple of Triple DES block
size) and unwrapping is also authenticated.

>>> unwrap(ciphertext, key) == plaintext
True
>>> unwrap(ciphertext[:-1], key)  # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
    ...
DecryptionError: Ciphertext length wrong
>>> unwrap(ciphertext[:-1] + b'A', key)  # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
    ...
DecryptionError: CMS key checksum error