#
# pubkey.py : Internal functions for public key operations
#
# Part of the Python Cryptography Toolkit
#
# Distribute and use freely; there are no restrictions on further
# dissemination and usage except those imposed by the laws of your
# country of residence. This software is provided "as is" without
# warranty of fitness for use or suitability for any purpose, express
# or implied. Use at your own risk or not at all.
#
__revision__ = "$Id: pubkey.py,v 1.11 2003/04/03 20:36:14 akuchling Exp $"
import types, warnings
from Crypto.Util.number import *
# Basic public key class
class pubkey:
def __init__(self):
pass
def __getstate__(self):
"""To keep key objects platform-independent, the key data is
converted to standard Python long integers before being
written out. It will then be reconverted as necessary on
restoration."""
d=self.__dict__
for key in self.keydata:
if d.has_key(key): d[key]=long(d[key])
return d
def __setstate__(self, d):
"""On unpickling a key object, the key data is converted to the big
number representation being used, whether that is Python long
integers, MPZ objects, or whatever."""
for key in self.keydata:
if d.has_key(key): self.__dict__[key]=bignum(d[key])
def encrypt(self, plaintext, K):
"""encrypt(plaintext:string|long, K:string|long) : tuple
Encrypt the string or integer plaintext. K is a random
parameter required by some algorithms.
"""
wasString=0
if isinstance(plaintext, types.StringType):
plaintext=bytes_to_long(plaintext) ; wasString=1
if isinstance(K, types.StringType):
K=bytes_to_long(K)
ciphertext=self._encrypt(plaintext, K)
if wasString: return tuple(map(long_to_bytes, ciphertext))
else: return ciphertext
def decrypt(self, ciphertext):
"""decrypt(ciphertext:tuple|string|long): string
Decrypt 'ciphertext' using this key.
"""
wasString=0
if not isinstance(ciphertext, types.TupleType):
ciphertext=(ciphertext,)
if isinstance(ciphertext[0], types.StringType):
ciphertext=tuple(map(bytes_to_long, ciphertext)) ; wasString=1
plaintext=self._decrypt(ciphertext)
if wasString: return long_to_bytes(plaintext)
else: return plaintext
def sign(self, M, K):
"""sign(M : string|long, K:string|long) : tuple
Return a tuple containing the signature for the message M.
K is a random parameter required by some algorithms.
"""
if (not self.has_private()):
raise error, 'Private key not available in this object'
if isinstance(M, types.StringType): M=bytes_to_long(M)
if isinstance(K, types.StringType): K=bytes_to_long(K)
return self._sign(M, K)
def verify (self, M, signature):
"""verify(M:string|long, signature:tuple) : bool
Verify that the signature is valid for the message M;
returns true if the signature checks out.
"""
if isinstance(M, types.StringType): M=bytes_to_long(M)
return self._verify(M, signature)
# alias to compensate for the old validate() name
def validate (self, M, signature):
warnings.warn("validate() method name is obsolete; use verify()",
DeprecationWarning)
def blind(self, M, B):
"""blind(M : string|long, B : string|long) : string|long
Blind message M using blinding factor B.
"""
wasString=0
if isinstance(M, types.StringType):
M=bytes_to_long(M) ; wasString=1
if isinstance(B, types.StringType): B=bytes_to_long(B)
blindedmessage=self._blind(M, B)
if wasString: return long_to_bytes(blindedmessage)
else: return blindedmessage
def unblind(self, M, B):
"""unblind(M : string|long, B : string|long) : string|long
Unblind message M using blinding factor B.
"""
wasString=0
if isinstance(M, types.StringType):
M=bytes_to_long(M) ; wasString=1
if isinstance(B, types.StringType): B=bytes_to_long(B)
unblindedmessage=self._unblind(M, B)
if wasString: return long_to_bytes(unblindedmessage)
else: return unblindedmessage
# The following methods will usually be left alone, except for
# signature-only algorithms. They both return Boolean values
# recording whether this key's algorithm can sign and encrypt.
def can_sign (self):
"""can_sign() : bool
Return a Boolean value recording whether this algorithm can
generate signatures. (This does not imply that this
particular key object has the private information required to
to generate a signature.)
"""
return 1
def can_encrypt (self):
"""can_encrypt() : bool
Return a Boolean value recording whether this algorithm can
encrypt data. (This does not imply that this
particular key object has the private information required to
to decrypt a message.)
"""
return 1
def can_blind (self):
"""can_blind() : bool
Return a Boolean value recording whether this algorithm can
blind data. (This does not imply that this
particular key object has the private information required to
to blind a message.)
"""
return 0
# The following methods will certainly be overridden by
# subclasses.
def size (self):
"""size() : int
Return the maximum number of bits that can be handled by this key.
"""
return 0
def has_private (self):
"""has_private() : bool
Return a Boolean denoting whether the object contains
private components.
"""
return 0
def publickey (self):
"""publickey(): object
Return a new key object containing only the public information.
"""
return self
def __eq__ (self, other):
"""__eq__(other): 0, 1
Compare us to other for equality.
"""
return self.__getstate__() == other.__getstate__()
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