#
# RSA.py : RSA encryption/decryption
#
# Part of the Python Cryptography Toolkit
#
# Written by Andrew Kuchling, Paul Swartz, and others
#
# ===================================================================
# The contents of this file are dedicated to the public domain. To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# ===================================================================
#
__revision__ = "$Id$"
from Crypto.PublicKey import pubkey
from Crypto.Util import number
def generate_py(bits, randfunc, progress_func=None, e=65537):
"""generate(bits:int, randfunc:callable, progress_func:callable, e:int)
Generate an RSA key of length 'bits', public exponent 'e'(which must be
odd), using 'randfunc' to get random data and 'progress_func',
if present, to display the progress of the key generation.
"""
obj=RSAobj()
obj.e = int(e)
# Generate the prime factors of n
if progress_func:
progress_func('p,q\n')
p = q = 1
while number.size(p*q) < bits:
# Note that q might be one bit longer than p if somebody specifies an odd
# number of bits for the key. (Why would anyone do that? You don't get
# more security.)
p = pubkey.getStrongPrime(bits>>1, obj.e, 1e-12, randfunc)
q = pubkey.getStrongPrime(bits - (bits>>1), obj.e, 1e-12, randfunc)
# It's OK for p to be larger than q, but let's be
# kind to the function that will invert it for
# th calculation of u.
if p > q:
(p, q)=(q, p)
obj.p = p
obj.q = q
if progress_func:
progress_func('u\n')
obj.u = pubkey.inverse(obj.p, obj.q)
obj.n = obj.p*obj.q
if progress_func:
progress_func('d\n')
obj.d=pubkey.inverse(obj.e, (obj.p-1)*(obj.q-1))
assert bits <= 1+obj.size(), "Generated key is too small"
return obj
class RSAobj(pubkey.pubkey):
def size(self):
"""size() : int
Return the maximum number of bits that can be handled by this key.
"""
return number.size(self.n) - 1