257 lines
6.8 KiB
Python
257 lines
6.8 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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# Distribute and use freely; there are no restrictions on further
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# dissemination and usage except those imposed by the laws of your
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# country of residence. This software is provided "as is" without
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# warranty of fitness for use or suitability for any purpose, express
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# or implied. Use at your own risk or not at all.
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#
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__revision__ = "$Id: RSA.py,v 1.20 2004/05/06 12:52:54 akuchling Exp $"
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from Crypto.PublicKey import pubkey
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from Crypto.Util import number
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try:
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from Crypto.PublicKey import _fastmath
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except ImportError:
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_fastmath = None
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class error (Exception):
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pass
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def generate(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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# 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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p = pubkey.getPrime(bits/2, randfunc)
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q = pubkey.getPrime(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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obj.e = 65537L
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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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def construct(tuple):
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"""construct(tuple:(long,) : RSAobj
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Construct an RSA object from a 2-, 3-, 5-, or 6-tuple of numbers.
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"""
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obj=RSAobj()
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if len(tuple) not in [2,3,5,6]:
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raise error, 'argument for construct() wrong length'
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for i in range(len(tuple)):
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field = obj.keydata[i]
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setattr(obj, field, tuple[i])
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if len(tuple) >= 5:
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# Ensure p is smaller than q
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if obj.p>obj.q:
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(obj.p, obj.q)=(obj.q, obj.p)
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if len(tuple) == 5:
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# u not supplied, so we're going to have to compute it.
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obj.u=pubkey.inverse(obj.p, obj.q)
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return obj
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class RSAobj(pubkey.pubkey):
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keydata = ['n', 'e', 'd', 'p', 'q', 'u']
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def _encrypt(self, plaintext, K=''):
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if self.n<=plaintext:
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raise error, 'Plaintext too large'
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return (pow(plaintext, self.e, self.n),)
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def _decrypt(self, ciphertext):
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if (not hasattr(self, 'd')):
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raise error, 'Private key not available in this object'
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if self.n<=ciphertext[0]:
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raise error, 'Ciphertext too large'
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return pow(ciphertext[0], self.d, self.n)
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def _sign(self, M, K=''):
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return (self._decrypt((M,)),)
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def _verify(self, M, sig):
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m2=self._encrypt(sig[0])
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if m2[0]==M:
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return 1
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else: return 0
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def _blind(self, M, B):
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tmp = pow(B, self.e, self.n)
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return (M * tmp) % self.n
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def _unblind(self, M, B):
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tmp = pubkey.inverse(B, self.n)
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return (M * tmp) % self.n
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def can_blind (self):
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"""can_blind() : bool
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Return a Boolean value recording whether this algorithm can
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blind data. (This does not imply that this
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particular key object has the private information required to
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to blind a message.)
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"""
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return 1
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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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def has_private(self):
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"""has_private() : bool
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Return a Boolean denoting whether the object contains
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private components.
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"""
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if hasattr(self, 'd'):
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return 1
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else: return 0
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def publickey(self):
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"""publickey(): RSAobj
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Return a new key object containing only the public key information.
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"""
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return construct((self.n, self.e))
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class RSAobj_c(pubkey.pubkey):
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keydata = ['n', 'e', 'd', 'p', 'q', 'u']
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def __init__(self, key):
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self.key = key
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def __getattr__(self, attr):
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if attr in self.keydata:
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return getattr(self.key, attr)
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else:
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if self.__dict__.has_key(attr):
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self.__dict__[attr]
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else:
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raise AttributeError, '%s instance has no attribute %s' % (self.__class__, attr)
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def __getstate__(self):
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d = {}
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for k in self.keydata:
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if hasattr(self.key, k):
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d[k]=getattr(self.key, k)
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return d
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def __setstate__(self, state):
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n,e = state['n'], state['e']
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if not state.has_key('d'):
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self.key = _fastmath.rsa_construct(n,e)
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else:
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d = state['d']
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if not state.has_key('q'):
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self.key = _fastmath.rsa_construct(n,e,d)
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else:
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p, q, u = state['p'], state['q'], state['u']
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self.key = _fastmath.rsa_construct(n,e,d,p,q,u)
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def _encrypt(self, plain, K):
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return (self.key._encrypt(plain),)
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def _decrypt(self, cipher):
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return self.key._decrypt(cipher[0])
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def _sign(self, M, K):
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return (self.key._sign(M),)
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def _verify(self, M, sig):
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return self.key._verify(M, sig[0])
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def _blind(self, M, B):
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return self.key._blind(M, B)
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def _unblind(self, M, B):
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return self.key._unblind(M, B)
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def can_blind (self):
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return 1
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def size(self):
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return self.key.size()
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def has_private(self):
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return self.key.has_private()
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def publickey(self):
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return construct_c((self.key.n, self.key.e))
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def generate_c(bits, randfunc, progress_func = None):
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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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p = pubkey.getPrime(bits/2, randfunc)
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q = pubkey.getPrime(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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if progress_func:
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progress_func('u\n')
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u=pubkey.inverse(p, q)
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n=p*q
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e = 65537L
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if progress_func:
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progress_func('d\n')
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d=pubkey.inverse(e, (p-1)*(q-1))
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key = _fastmath.rsa_construct(n,e,d,p,q,u)
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obj = RSAobj_c(key)
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## print p
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## print q
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## print number.size(p), number.size(q), number.size(q*p),
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## print obj.size(), bits
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assert bits <= 1+obj.size(), "Generated key is too small"
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return obj
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def construct_c(tuple):
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key = apply(_fastmath.rsa_construct, tuple)
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return RSAobj_c(key)
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object = RSAobj
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generate_py = generate
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construct_py = construct
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if _fastmath:
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#print "using C version of RSA"
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generate = generate_c
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construct = construct_c
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error = _fastmath.error
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