82 lines
2.8 KiB
Python
82 lines
2.8 KiB
Python
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#
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# RSA.py : RSA encryption/decryption
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#
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# Part of the Python Cryptography Toolkit
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#
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# Written by Andrew Kuchling, Paul Swartz, and others
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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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#
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__revision__ = "$Id$"
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from Crypto.PublicKey import pubkey
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from Crypto.Util import number
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def generate_py(bits, randfunc, progress_func=None, e=65537):
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"""generate(bits:int, randfunc:callable, progress_func:callable, e:int)
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Generate an RSA key of length 'bits', public exponent 'e'(which must be
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odd), using 'randfunc' to get random data and 'progress_func',
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if present, to display the progress of the key generation.
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"""
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obj=RSAobj()
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obj.e = int(e)
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# Generate the prime factors of n
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if progress_func:
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progress_func('p,q\n')
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p = q = 1
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while number.size(p*q) < bits:
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# Note that q might be one bit longer than p if somebody specifies an odd
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# number of bits for the key. (Why would anyone do that? You don't get
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# more security.)
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p = pubkey.getStrongPrime(bits>>1, obj.e, 1e-12, randfunc)
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q = pubkey.getStrongPrime(bits - (bits>>1), obj.e, 1e-12, randfunc)
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# It's OK for p to be larger than q, but let's be
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# kind to the function that will invert it for
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# th calculation of u.
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if p > q:
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(p, q)=(q, p)
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obj.p = p
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obj.q = q
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if progress_func:
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progress_func('u\n')
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obj.u = pubkey.inverse(obj.p, obj.q)
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obj.n = obj.p*obj.q
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if progress_func:
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progress_func('d\n')
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obj.d=pubkey.inverse(obj.e, (obj.p-1)*(obj.q-1))
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assert bits <= 1+obj.size(), "Generated key is too small"
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return obj
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class RSAobj(pubkey.pubkey):
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def size(self):
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"""size() : int
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Return the maximum number of bits that can be handled by this key.
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"""
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return number.size(self.n) - 1
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