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"""Abstract class for RSA."""
from cryptomath import *
class RSAKey:
"""This is an abstract base class for RSA keys.
Particular implementations of RSA keys, such as
L{OpenSSL_RSAKey.OpenSSL_RSAKey},
L{Python_RSAKey.Python_RSAKey}, and
L{PyCrypto_RSAKey.PyCrypto_RSAKey},
inherit from this.
To create or parse an RSA key, don't use one of these classes
directly. Instead, use the factory functions in
L{tlslite.utils.keyfactory}.
"""
def __init__(self, n=0, e=0):
"""Create a new RSA key.
If n and e are passed in, the new key will be initialized.
@type n: int
@param n: RSA modulus.
@type e: int
@param e: RSA public exponent.
"""
raise NotImplementedError()
def __len__(self):
"""Return the length of this key in bits.
@rtype: int
"""
return numBits(self.n)
def hasPrivateKey(self):
"""Return whether or not this key has a private component.
@rtype: bool
"""
raise NotImplementedError()
def hash(self):
"""Return the cryptoID <keyHash> value corresponding to this
key.
@rtype: str
"""
raise NotImplementedError()
def getSigningAlgorithm(self):
"""Return the cryptoID sigAlgo value corresponding to this key.
@rtype: str
"""
return "pkcs1-sha1"
def hashAndSign(self, bytes):
"""Hash and sign the passed-in bytes.
This requires the key to have a private component. It performs
a PKCS1-SHA1 signature on the passed-in data.
@type bytes: str or L{array.array} of unsigned bytes
@param bytes: The value which will be hashed and signed.
@rtype: L{array.array} of unsigned bytes.
@return: A PKCS1-SHA1 signature on the passed-in data.
"""
if not isinstance(bytes, type("")):
bytes = bytesToString(bytes)
hashBytes = stringToBytes(sha.sha(bytes).digest())
prefixedHashBytes = self._addPKCS1SHA1Prefix(hashBytes)
sigBytes = self.sign(prefixedHashBytes)
return sigBytes
def hashAndVerify(self, sigBytes, bytes):
"""Hash and verify the passed-in bytes with the signature.
This verifies a PKCS1-SHA1 signature on the passed-in data.
@type sigBytes: L{array.array} of unsigned bytes
@param sigBytes: A PKCS1-SHA1 signature.
@type bytes: str or L{array.array} of unsigned bytes
@param bytes: The value which will be hashed and verified.
@rtype: bool
@return: Whether the signature matches the passed-in data.
"""
if not isinstance(bytes, type("")):
bytes = bytesToString(bytes)
hashBytes = stringToBytes(sha.sha(bytes).digest())
prefixedHashBytes = self._addPKCS1SHA1Prefix(hashBytes)
return self.verify(sigBytes, prefixedHashBytes)
def sign(self, bytes):
"""Sign the passed-in bytes.
This requires the key to have a private component. It performs
a PKCS1 signature on the passed-in data.
@type bytes: L{array.array} of unsigned bytes
@param bytes: The value which will be signed.
@rtype: L{array.array} of unsigned bytes.
@return: A PKCS1 signature on the passed-in data.
"""
if not self.hasPrivateKey():
raise AssertionError()
paddedBytes = self._addPKCS1Padding(bytes, 1)
m = bytesToNumber(paddedBytes)
if m >= self.n:
raise ValueError()
c = self._rawPrivateKeyOp(m)
sigBytes = numberToBytes(c)
return sigBytes
def verify(self, sigBytes, bytes):
"""Verify the passed-in bytes with the signature.
This verifies a PKCS1 signature on the passed-in data.
@type sigBytes: L{array.array} of unsigned bytes
@param sigBytes: A PKCS1 signature.
@type bytes: L{array.array} of unsigned bytes
@param bytes: The value which will be verified.
@rtype: bool
@return: Whether the signature matches the passed-in data.
"""
paddedBytes = self._addPKCS1Padding(bytes, 1)
c = bytesToNumber(sigBytes)
if c >= self.n:
return False
m = self._rawPublicKeyOp(c)
checkBytes = numberToBytes(m)
return checkBytes == paddedBytes
def encrypt(self, bytes):
"""Encrypt the passed-in bytes.
This performs PKCS1 encryption of the passed-in data.
@type bytes: L{array.array} of unsigned bytes
@param bytes: The value which will be encrypted.
@rtype: L{array.array} of unsigned bytes.
@return: A PKCS1 encryption of the passed-in data.
"""
paddedBytes = self._addPKCS1Padding(bytes, 2)
m = bytesToNumber(paddedBytes)
if m >= self.n:
raise ValueError()
c = self._rawPublicKeyOp(m)
encBytes = numberToBytes(c)
return encBytes
def decrypt(self, encBytes):
"""Decrypt the passed-in bytes.
This requires the key to have a private component. It performs
PKCS1 decryption of the passed-in data.
@type encBytes: L{array.array} of unsigned bytes
@param encBytes: The value which will be decrypted.
@rtype: L{array.array} of unsigned bytes or None.
@return: A PKCS1 decryption of the passed-in data or None if
the data is not properly formatted.
"""
if not self.hasPrivateKey():
raise AssertionError()
c = bytesToNumber(encBytes)
if c >= self.n:
return None
m = self._rawPrivateKeyOp(c)
decBytes = numberToBytes(m)
if (len(decBytes) != numBytes(self.n)-1): #Check first byte
return None
if decBytes[0] != 2: #Check second byte
return None
for x in range(len(decBytes)-1): #Scan through for zero separator
if decBytes[x]== 0:
break
else:
return None
return decBytes[x+1:] #Return everything after the separator
def _rawPrivateKeyOp(self, m):
raise NotImplementedError()
def _rawPublicKeyOp(self, c):
raise NotImplementedError()
def acceptsPassword(self):
"""Return True if the write() method accepts a password for use
in encrypting the private key.
@rtype: bool
"""
raise NotImplementedError()
def write(self, password=None):
"""Return a string containing the key.
@rtype: str
@return: A string describing the key, in whichever format (PEM
or XML) is native to the implementation.
"""
raise NotImplementedError()
def writeXMLPublicKey(self, indent=''):
"""Return a string containing the key.
@rtype: str
@return: A string describing the public key, in XML format.
"""
return Python_RSAKey(self.n, self.e).write(indent)
def generate(bits):
"""Generate a new key with the specified bit length.
@rtype: L{tlslite.utils.RSAKey.RSAKey}
"""
raise NotImplementedError()
generate = staticmethod(generate)
# **************************************************************************
# Helper Functions for RSA Keys
# **************************************************************************
def _addPKCS1SHA1Prefix(self, bytes):
prefixBytes = createByteArraySequence(\
[48,33,48,9,6,5,43,14,3,2,26,5,0,4,20])
prefixedBytes = prefixBytes + bytes
return prefixedBytes
def _addPKCS1Padding(self, bytes, blockType):
padLength = (numBytes(self.n) - (len(bytes)+3))
if blockType == 1: #Signature padding
pad = [0xFF] * padLength
elif blockType == 2: #Encryption padding
pad = createByteArraySequence([])
while len(pad) < padLength:
padBytes = getRandomBytes(padLength * 2)
pad = [b for b in padBytes if b != 0]
pad = pad[:padLength]
else:
raise AssertionError()
#NOTE: To be proper, we should add [0,blockType]. However,
#the zero is lost when the returned padding is converted
#to a number, so we don't even bother with it. Also,
#adding it would cause a misalignment in verify()
padding = createByteArraySequence([blockType] + pad + [0])
paddedBytes = padding + bytes
return paddedBytes
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