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https://github.com/Legrandin/pycryptodome.git
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90d6d3dbcf
The patch contains the following changes: - Private RSA keys can be imported/exported in encrypted form, protected according to PKCS#8 and: * PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC. * PBKDF2WithHMAC-SHA1AndAES128-CBC * PBKDF2WithHMAC-SHA1AndAES192-CBC * PBKDF2WithHMAC-SHA1AndAES256-CBC In addition to that, it is possible to import keys i the following weak formats: * pbeWithMD5AndDES-CBC * pbeWithSHA1AndRC2-CBC * pbeWithMD5AndRC2-CBC * pbeWithSHA1AndDES-CBC - The following new module (and 1 new package) are added: * Crypto.Util.Padding for simple padding/unpadding logic * Crypto.IO._PBES for PBE-related PKCS#5 logic * Crypto.IO.PEM for PEM wrapping/unwrapping * Crypto.IO.PKCS8 for PKCS#8 wrapping/unwrapping - All Object ID (OIDs) are now in dotted form to increase readability. - Add AES support to PEM format (decode only). The PEM module can decrypt messages protected with AES-CBC. - Update RSA import test cases. - Updated to PKCS8 test cases
103 lines
3.9 KiB
Python
103 lines
3.9 KiB
Python
#
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# -*- coding: utf-8 -*-
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#
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# Util/Padding.py : Functions to manage padding
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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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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""" Functions to manage padding
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This module provides minimal support for adding and removing standard padding
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from data.
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"""
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__all__ = [ 'PaddingError', 'pad', 'unpad' ]
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from Crypto.Util.py3compat import *
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class PaddingError(ValueError):
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"""Exception raised when padding is incorrect and cannot be removed."""
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pass
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def pad(data_to_pad, block_size, style='pkcs7'):
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"""Apply standard padding.
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:Parameters:
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data_to_pad : byte string
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The data that needs to be padded.
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block_size : integer
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The block boundary to use for padding. The output length is guaranteed
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to be a multiple of ``block_size``.
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style : string
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Padding algorithm. It can be *'pkcs7'* (default), *'iso7816'* or *'x923'*.
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:Return:
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The original data with the appropriate padding added at the end.
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"""
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padding_len = block_size-len(data_to_pad)%block_size
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if style == 'pkcs7':
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padding = bchr(padding_len)*padding_len
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elif style == 'x923':
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padding = bchr(0)*(padding_len-1) + bchr(padding_len)
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elif style == 'iso7816':
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padding = bchr(128) + bchr(0)*(padding_len-1)
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else:
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raise ValueError("Unknown padding style")
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return data_to_pad + padding
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def unpad(padded_data, block_size, style='pkcs7'):
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"""Remove standard padding.
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:Parameters:
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padded_data : byte string
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A piece of data with padding that needs to be stripped.
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block_size : integer
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The block boundary to use for padding. The input length
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must be a multiple of ``block_size``.
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style : string
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Padding algorithm. It can be *'pkcs7'* (default), *'iso7816'* or *'x923'*.
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:Return:
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Data without padding.
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:Raises PaddingError:
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if the padding is incorrect.
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"""
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pdata_len = len(padded_data)
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if pdata_len % block_size:
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raise PaddingError("Input data is not padded")
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if style in ('pkcs7', 'x923'):
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padding_len = bord(padded_data[-1])
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if padding_len<1 or padding_len>min(block_size, pdata_len):
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raise PaddingError("Padding is incorrect.")
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if style == 'pkcs7':
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if padded_data[-padding_len:]!=bchr(padding_len)*padding_len:
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raise PaddingError("PKCS#7 padding is incorrect.")
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else:
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if padded_data[-padding_len:-1]!=bchr(0)*(padding_len-1):
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raise PaddingError("ANSI X.923 padding is incorrect.")
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elif style == 'iso7816':
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padding_len = pdata_len - padded_data.rfind(bchr(128))
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if padding_len<1 or padding_len>min(block_size, pdata_len):
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raise PaddingError("Padding is incorrect.")
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if padding_len>1 and padded_data[1-padding_len:]!=bchr(0)*(padding_len-1):
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raise PaddingError("ISO 7816-4 padding is incorrect.")
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else:
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raise ValueError("Unknown padding style")
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return padded_data[:-padding_len]
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