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https://github.com/noDRM/DeDRM_tools.git
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96 lines
3.2 KiB
Python
96 lines
3.2 KiB
Python
#
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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):
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"""generate(bits:int, randfunc:callable, progress_func:callable)
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Generate an RSA key of length 'bits', using 'randfunc' to get
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random data and 'progress_func', if present, to display
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the progress of the key generation.
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"""
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obj=RSAobj()
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obj.e = 65537L
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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 = 1L
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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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#
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# Note also that we ensure that e is coprime to (p-1) and (q-1).
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# This is needed for encryption to work properly, according to the 1997
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# paper by Robert D. Silverman of RSA Labs, "Fast generation of random,
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# strong RSA primes", available at
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# http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.17.2713&rep=rep1&type=pdf
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# Since e=65537 is prime, it is sufficient to check that e divides
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# neither (p-1) nor (q-1).
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p = 1L
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while (p - 1) % obj.e == 0:
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if progress_func:
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progress_func('p\n')
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p = pubkey.getPrime(bits/2, randfunc)
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q = 1L
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while (q - 1) % obj.e == 0:
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if progress_func:
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progress_func('q\n')
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q = pubkey.getPrime(bits - (bits/2), randfunc)
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# p shall be smaller than q (for calc 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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