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Added remaining ciphers to API
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Helder Eijs
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10 changed files with 402 additions and 414 deletions
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@ -19,39 +19,16 @@
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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"""RC2 symmetric cipher
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"""
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Module's constants for the modes of operation supported with ARC2:
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RC2_ (Rivest's Cipher version 2) is a symmetric block cipher designed
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by Ron Rivest in 1987. The cipher started as a proprietary design,
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that was reverse engineered and anonymously posted on Usenet in 1996.
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For this reason, the algorithm was first called *Alleged* RC2 (ARC2),
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since the company that owned RC2 (RSA Data Inc.) did not confirm whether
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the details leaked into public domain were really correct.
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The company eventually published its full specification in RFC2268_.
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RC2 has a fixed data block size of 8 bytes. Length of its keys can vary from
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8 to 128 bits. One particular property of RC2 is that the actual
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cryptographic strength of the key (*effective key length*) can be reduced
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via a parameter.
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Even though RC2 is not cryptographically broken, it has not been analyzed as
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thoroughly as AES, which is also faster than RC2.
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**Use AES, not ARC2. This module is only provided for legacy purposes.**
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As an example, encryption can be done as follows:
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>>> from Crypto.Cipher import ARC2
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>>>
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>>> key = b'Sixteen byte key'
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>>> cipher = ARC2.new(key, ARC2.MODE_CFB)
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>>> msg = cipher.iv + cipher.encrypt(b'Attack at dawn')
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.. _RC2: http://en.wikipedia.org/wiki/RC2
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.. _RFC2268: http://tools.ietf.org/html/rfc2268
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:undocumented: __package__
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:var MODE_ECB: Electronic Code Book (ECB)
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:var MODE_CBC: Cipher-Block Chaining (CBC)
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:var MODE_CFB: Cipher FeedBack (CFB)
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:var MODE_OFB: Output FeedBack (OFB)
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:var MODE_CTR: CounTer Mode (CTR)
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:var MODE_OPENPGP: OpenPGP Mode
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:var MODE_EAX: EAX Mode
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"""
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import sys
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@ -118,101 +95,76 @@ def _create_base_cipher(dict_parameters):
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def new(key, mode, *args, **kwargs):
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"""Create a new RC2 cipher
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"""Create a new RC2 cipher.
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:Parameters:
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key : byte string
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:param key:
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The secret key to use in the symmetric cipher.
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Its length can vary from 5 to 128 bytes.
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:type key: byte string
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mode : a *MODE_** constant
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:param mode:
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The chaining mode to use for encryption or decryption.
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:type mode: One of the supported ``MODE_*`` constants
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:Keywords:
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iv : byte string
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(*Only* `MODE_CBC`, `MODE_CFB`, `MODE_OFB`, `MODE_OPENPGP`).
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:Keyword Arguments:
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* *iv* (``byte string``) --
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(Only applicable for ``MODE_CBC``, ``MODE_CFB``, ``MODE_OFB``,
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and ``MODE_OPENPGP`` modes).
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The initialization vector to use for encryption or decryption.
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The initialization vector to use for encryption or decryption.
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For `MODE_OPENPGP`, IV must be 8 bytes long for encryption
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and 10 bytes for decryption (in the latter case, it is
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actually the *encrypted* IV which was prefixed to the ciphertext).
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For ``MODE_CBC``, ``MODE_CFB``, and ``MODE_OFB`` it must be 8 bytes long.
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For all other modes, it must be 8 bytes long.
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For ``MODE_OPENPGP`` mode only,
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it must be 8 bytes long for encryption
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and 10 bytes for decryption (in the latter case, it is
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actually the *encrypted* IV which was prefixed to the ciphertext).
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If not provided, a random byte string will be generated (you
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must read it back via the ``iv`` attribute of the cipher).
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If not provided, a random byte string is generated (you must then
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read its value with the :attr:`iv` attribute).
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nonce : byte string
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(*Only* `MODE_EAX` and `MODE_CTR`).
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A value that must never be reused for any other encryption done with
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this key.
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* *nonce* (``byte string``) --
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(Only applicable for ``MODE_EAX`` and ``MODE_CTR``).
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For `MODE_CTR`, its length must be in the range ``[0..7]``.
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A value that must never be reused for any other encryption done
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with this key.
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For `MODE_EAX`, there are no restrictions, but it is recommended to
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use at least 16 bytes.
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For ``MODE_EAX`` there are no
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restrictions on its length (recommended: **16** bytes).
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If not provided for `MODE_EAX`, a random byte string will be
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generated (you must read it back via the ``nonce`` attribute
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of the cipher).
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For ``MODE_CTR``, its length must be in the range **[0..7]**.
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mac_len : integer
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(*Only* `MODE_EAX`). Length of the authentication tag, in bytes.
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It must be no larger than 8 (which is the default).
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If not provided for ``MODE_EAX``, a random byte string is generated (you
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can read it back via the ``nonce`` attribute).
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segment_size : integer
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(*Only* `MODE_CFB`).
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The number of **bits** the plaintext and ciphertext are segmented in.
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It must be a multiple of 8. If not specified,
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it will be assumed to be 8.
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* *segment_size* (``integer``) --
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(Only ``MODE_CFB``).The number of **bits** the plaintext and ciphertext
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are segmented in. It must be a multiple of 8.
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If not specified, it will be assumed to be 8.
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initial_value : integer
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(*Only* `MODE_CTR`). The initial value for the counter within
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the counter block. By default it is 0.
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* *mac_len* : (``integer``) --
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(Only ``MODE_EAX``)
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Length of the authentication tag, in bytes.
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It must be no longer than 8 (default).
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effective_keylen : integer
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Maximum cryptographic strength of the key, in **bits**.
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It can vary from 40 to 1024. The default value is 1024.
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:Return: an RC2 cipher object, of the applicable mode:
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- CBC_ mode
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- CFB_ mode
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- CTR_ mode
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- EAX_ mode
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- ECB_ mode
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- OFB_ mode
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- OpenPgp_ mode
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.. _CBC: Crypto.Cipher._mode_cbc.CbcMode-class.html
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.. _CFB: Crypto.Cipher._mode_cfb.CfbMode-class.html
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.. _CTR: Crypto.Cipher._mode_ctr.CtrMode-class.html
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.. _EAX: Crypto.Cipher._mode_eax.EaxMode-class.html
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.. _ECB: Crypto.Cipher._mode_ecb.EcbMode-class.html
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.. _OFB: Crypto.Cipher._mode_ofb.OfbMode-class.html
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.. _OpenPgp: Crypto.Cipher._mode_openpgp.OpenPgpMode-class.html
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* *initial_value* : (``integer``) --
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(Only ``MODE_CTR``). The initial value for the counter within
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the counter block. By default it is **0**.
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:Return: an ARC2 object, of the applicable mode.
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"""
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return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs)
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#: Electronic Code Book (ECB). See `Crypto.Cipher._mode_ecb.EcbMode`.
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MODE_ECB = 1
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#: Cipher-Block Chaining (CBC). See `Crypto.Cipher._mode_cbc.CbcMode`.
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MODE_CBC = 2
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#: Cipher FeedBack (CFB). See `Crypto.Cipher._mode_cfb.CfbMode`.
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MODE_CFB = 3
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#: Output FeedBack (OFB). See `Crypto.Cipher._mode_ofb.OfbMode`.
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MODE_OFB = 5
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#: CounTer Mode (CTR). See `Crypto.Cipher._mode_ctr.CtrMode`.
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MODE_CTR = 6
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#: OpenPGP Mode. See `Crypto.Cipher._mode_openpgp.OpenPgpMode`.
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MODE_OPENPGP = 7
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#: EAX Mode. See `Crypto.Cipher._mode_eax.EaxMode`.
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MODE_EAX = 9
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#: Size of a data block (in bytes)
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# Size of a data block (in bytes)
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block_size = 8
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#: Size of a key (in bytes)
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# Size of a key (in bytes)
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key_size = xrange(5, 128 + 1)
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