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159
python/gdata/tlslite/HandshakeSettings.py
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159
python/gdata/tlslite/HandshakeSettings.py
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"""Class for setting handshake parameters."""
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from constants import CertificateType
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from utils import cryptomath
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from utils import cipherfactory
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class HandshakeSettings:
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"""This class encapsulates various parameters that can be used with
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a TLS handshake.
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@sort: minKeySize, maxKeySize, cipherNames, certificateTypes,
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minVersion, maxVersion
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@type minKeySize: int
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@ivar minKeySize: The minimum bit length for asymmetric keys.
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If the other party tries to use SRP, RSA, or Diffie-Hellman
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parameters smaller than this length, an alert will be
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signalled. The default is 1023.
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@type maxKeySize: int
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@ivar maxKeySize: The maximum bit length for asymmetric keys.
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If the other party tries to use SRP, RSA, or Diffie-Hellman
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parameters larger than this length, an alert will be signalled.
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The default is 8193.
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@type cipherNames: list
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@ivar cipherNames: The allowed ciphers, in order of preference.
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The allowed values in this list are 'aes256', 'aes128', '3des', and
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'rc4'. If these settings are used with a client handshake, they
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determine the order of the ciphersuites offered in the ClientHello
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message.
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If these settings are used with a server handshake, the server will
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choose whichever ciphersuite matches the earliest entry in this
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list.
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NOTE: If '3des' is used in this list, but TLS Lite can't find an
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add-on library that supports 3DES, then '3des' will be silently
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removed.
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The default value is ['aes256', 'aes128', '3des', 'rc4'].
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@type certificateTypes: list
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@ivar certificateTypes: The allowed certificate types, in order of
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preference.
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The allowed values in this list are 'x509' and 'cryptoID'. This
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list is only used with a client handshake. The client will
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advertise to the server which certificate types are supported, and
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will check that the server uses one of the appropriate types.
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NOTE: If 'cryptoID' is used in this list, but cryptoIDlib is not
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installed, then 'cryptoID' will be silently removed.
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@type minVersion: tuple
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@ivar minVersion: The minimum allowed SSL/TLS version.
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This variable can be set to (3,0) for SSL 3.0, (3,1) for
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TLS 1.0, or (3,2) for TLS 1.1. If the other party wishes to
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use a lower version, a protocol_version alert will be signalled.
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The default is (3,0).
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@type maxVersion: tuple
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@ivar maxVersion: The maximum allowed SSL/TLS version.
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This variable can be set to (3,0) for SSL 3.0, (3,1) for
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TLS 1.0, or (3,2) for TLS 1.1. If the other party wishes to
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use a higher version, a protocol_version alert will be signalled.
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The default is (3,2). (WARNING: Some servers may (improperly)
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reject clients which offer support for TLS 1.1. In this case,
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try lowering maxVersion to (3,1)).
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"""
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def __init__(self):
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self.minKeySize = 1023
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self.maxKeySize = 8193
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self.cipherNames = ["aes256", "aes128", "3des", "rc4"]
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self.cipherImplementations = ["cryptlib", "openssl", "pycrypto",
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"python"]
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self.certificateTypes = ["x509", "cryptoID"]
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self.minVersion = (3,0)
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self.maxVersion = (3,2)
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#Filters out options that are not supported
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def _filter(self):
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other = HandshakeSettings()
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other.minKeySize = self.minKeySize
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other.maxKeySize = self.maxKeySize
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other.cipherNames = self.cipherNames
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other.cipherImplementations = self.cipherImplementations
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other.certificateTypes = self.certificateTypes
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other.minVersion = self.minVersion
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other.maxVersion = self.maxVersion
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if not cipherfactory.tripleDESPresent:
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other.cipherNames = [e for e in self.cipherNames if e != "3des"]
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if len(other.cipherNames)==0:
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raise ValueError("No supported ciphers")
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try:
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import cryptoIDlib
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except ImportError:
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other.certificateTypes = [e for e in self.certificateTypes \
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if e != "cryptoID"]
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if len(other.certificateTypes)==0:
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raise ValueError("No supported certificate types")
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if not cryptomath.cryptlibpyLoaded:
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other.cipherImplementations = [e for e in \
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self.cipherImplementations if e != "cryptlib"]
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if not cryptomath.m2cryptoLoaded:
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other.cipherImplementations = [e for e in \
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other.cipherImplementations if e != "openssl"]
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if not cryptomath.pycryptoLoaded:
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other.cipherImplementations = [e for e in \
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other.cipherImplementations if e != "pycrypto"]
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if len(other.cipherImplementations)==0:
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raise ValueError("No supported cipher implementations")
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if other.minKeySize<512:
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raise ValueError("minKeySize too small")
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if other.minKeySize>16384:
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raise ValueError("minKeySize too large")
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if other.maxKeySize<512:
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raise ValueError("maxKeySize too small")
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if other.maxKeySize>16384:
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raise ValueError("maxKeySize too large")
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for s in other.cipherNames:
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if s not in ("aes256", "aes128", "rc4", "3des"):
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raise ValueError("Unknown cipher name: '%s'" % s)
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for s in other.cipherImplementations:
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if s not in ("cryptlib", "openssl", "python", "pycrypto"):
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raise ValueError("Unknown cipher implementation: '%s'" % s)
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for s in other.certificateTypes:
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if s not in ("x509", "cryptoID"):
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raise ValueError("Unknown certificate type: '%s'" % s)
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if other.minVersion > other.maxVersion:
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raise ValueError("Versions set incorrectly")
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if not other.minVersion in ((3,0), (3,1), (3,2)):
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raise ValueError("minVersion set incorrectly")
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if not other.maxVersion in ((3,0), (3,1), (3,2)):
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raise ValueError("maxVersion set incorrectly")
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return other
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def _getCertificateTypes(self):
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l = []
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for ct in self.certificateTypes:
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if ct == "x509":
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l.append(CertificateType.x509)
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elif ct == "cryptoID":
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l.append(CertificateType.cryptoID)
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else:
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raise AssertionError()
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return l
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