| # Authors: |
| # Trevor Perrin |
| # Dave Baggett (Arcode Corporation) - cleanup handling of constants |
| # Yngve Pettersen (ported by Paul Sokolovsky) - TLS 1.2 |
| # |
| # See the LICENSE file for legal information regarding use of this file. |
| |
| """Class for setting handshake parameters.""" |
| |
| from .constants import CertificateType |
| from .utils import cryptomath |
| from .utils import cipherfactory |
| |
| # RC4 is preferred as faster in Python, works in SSL3, and immune to CBC |
| # issues such as timing attacks |
| CIPHER_NAMES = ["rc4", "aes256", "aes128", "3des"] |
| MAC_NAMES = ["sha", "sha256"] # Don't allow "md5" by default. |
| ALL_MAC_NAMES = ["sha", "sha256", "md5"] |
| KEY_EXCHANGE_NAMES = ["rsa", "dhe_rsa", "srp_sha", "srp_sha_rsa", "dh_anon"] |
| CIPHER_IMPLEMENTATIONS = ["openssl", "pycrypto", "python"] |
| CERTIFICATE_TYPES = ["x509"] |
| TLS_INTOLERANCE_TYPES = ["alert", "close", "reset"] |
| |
| class HandshakeSettings(object): |
| """This class encapsulates various parameters that can be used with |
| a TLS handshake. |
| @sort: minKeySize, maxKeySize, cipherNames, macNames, certificateTypes, |
| minVersion, maxVersion |
| |
| @type minKeySize: int |
| @ivar minKeySize: The minimum bit length for asymmetric keys. |
| |
| If the other party tries to use SRP, RSA, or Diffie-Hellman |
| parameters smaller than this length, an alert will be |
| signalled. The default is 1023. |
| |
| @type maxKeySize: int |
| @ivar maxKeySize: The maximum bit length for asymmetric keys. |
| |
| If the other party tries to use SRP, RSA, or Diffie-Hellman |
| parameters larger than this length, an alert will be signalled. |
| The default is 8193. |
| |
| @type cipherNames: list |
| @ivar cipherNames: The allowed ciphers, in order of preference. |
| |
| The allowed values in this list are 'aes256', 'aes128', '3des', and |
| 'rc4'. If these settings are used with a client handshake, they |
| determine the order of the ciphersuites offered in the ClientHello |
| message. |
| |
| If these settings are used with a server handshake, the server will |
| choose whichever ciphersuite matches the earliest entry in this |
| list. |
| |
| NOTE: If '3des' is used in this list, but TLS Lite can't find an |
| add-on library that supports 3DES, then '3des' will be silently |
| removed. |
| |
| The default value is ['rc4', 'aes256', 'aes128', '3des']. |
| |
| @type macNames: list |
| @ivar macNames: The allowed MAC algorithms. |
| |
| The allowed values in this list are 'sha' and 'md5'. |
| |
| The default value is ['sha']. |
| |
| |
| @type certificateTypes: list |
| @ivar certificateTypes: The allowed certificate types, in order of |
| preference. |
| |
| The only allowed certificate type is 'x509'. This list is only used with a |
| client handshake. The client will advertise to the server which certificate |
| types are supported, and will check that the server uses one of the |
| appropriate types. |
| |
| |
| @type minVersion: tuple |
| @ivar minVersion: The minimum allowed SSL/TLS version. |
| |
| This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for |
| TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a lower |
| version, a protocol_version alert will be signalled. The default is (3,1). |
| |
| @type maxVersion: tuple |
| @ivar maxVersion: The maximum allowed SSL/TLS version. |
| |
| This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for |
| TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a higher |
| version, a protocol_version alert will be signalled. The default is (3,3). |
| (WARNING: Some servers may (improperly) reject clients which offer support |
| for TLS 1.1. In this case, try lowering maxVersion to (3,1)). |
| |
| @type tlsIntolerant: tuple |
| @ivar tlsIntolerant: The TLS ClientHello version which the server |
| simulates intolerance of. |
| |
| If tlsIntolerant is not None, the server will simulate TLS version |
| intolerance by aborting the handshake in response to all TLS versions |
| tlsIntolerant or higher. |
| |
| @type tlsIntoleranceType: str |
| @ivar tlsIntoleranceType: How the server should react when simulating TLS |
| intolerance. |
| |
| The allowed values are "alert" (return a fatal handshake_failure alert), |
| "close" (abruptly close the connection), and "reset" (send a TCP reset). |
| |
| @type useExperimentalTackExtension: bool |
| @ivar useExperimentalTackExtension: Whether to enabled TACK support. |
| |
| Note that TACK support is not standardized by IETF and uses a temporary |
| TLS Extension number, so should NOT be used in production software. |
| """ |
| def __init__(self): |
| self.minKeySize = 1023 |
| self.maxKeySize = 8193 |
| self.cipherNames = CIPHER_NAMES |
| self.macNames = MAC_NAMES |
| self.keyExchangeNames = KEY_EXCHANGE_NAMES |
| self.cipherImplementations = CIPHER_IMPLEMENTATIONS |
| self.certificateTypes = CERTIFICATE_TYPES |
| self.minVersion = (3,1) |
| self.maxVersion = (3,3) |
| self.tlsIntolerant = None |
| self.tlsIntoleranceType = 'alert' |
| self.useExperimentalTackExtension = False |
| |
| # Validates the min/max fields, and certificateTypes |
| # Filters out unsupported cipherNames and cipherImplementations |
| def _filter(self): |
| other = HandshakeSettings() |
| other.minKeySize = self.minKeySize |
| other.maxKeySize = self.maxKeySize |
| other.cipherNames = self.cipherNames |
| other.macNames = self.macNames |
| other.keyExchangeNames = self.keyExchangeNames |
| other.cipherImplementations = self.cipherImplementations |
| other.certificateTypes = self.certificateTypes |
| other.minVersion = self.minVersion |
| other.maxVersion = self.maxVersion |
| other.tlsIntolerant = self.tlsIntolerant |
| other.tlsIntoleranceType = self.tlsIntoleranceType |
| |
| if not cipherfactory.tripleDESPresent: |
| other.cipherNames = [e for e in self.cipherNames if e != "3des"] |
| if len(other.cipherNames)==0: |
| raise ValueError("No supported ciphers") |
| if len(other.certificateTypes)==0: |
| raise ValueError("No supported certificate types") |
| |
| if not cryptomath.m2cryptoLoaded: |
| other.cipherImplementations = \ |
| [e for e in other.cipherImplementations if e != "openssl"] |
| if not cryptomath.pycryptoLoaded: |
| other.cipherImplementations = \ |
| [e for e in other.cipherImplementations if e != "pycrypto"] |
| if len(other.cipherImplementations)==0: |
| raise ValueError("No supported cipher implementations") |
| |
| if other.minKeySize<512: |
| raise ValueError("minKeySize too small") |
| if other.minKeySize>16384: |
| raise ValueError("minKeySize too large") |
| if other.maxKeySize<512: |
| raise ValueError("maxKeySize too small") |
| if other.maxKeySize>16384: |
| raise ValueError("maxKeySize too large") |
| for s in other.cipherNames: |
| if s not in CIPHER_NAMES: |
| raise ValueError("Unknown cipher name: '%s'" % s) |
| for s in other.macNames: |
| if s not in ALL_MAC_NAMES: |
| raise ValueError("Unknown MAC name: '%s'" % s) |
| for s in other.keyExchangeNames: |
| if s not in KEY_EXCHANGE_NAMES: |
| raise ValueError("Unknown key exchange name: '%s'" % s) |
| for s in other.cipherImplementations: |
| if s not in CIPHER_IMPLEMENTATIONS: |
| raise ValueError("Unknown cipher implementation: '%s'" % s) |
| for s in other.certificateTypes: |
| if s not in CERTIFICATE_TYPES: |
| raise ValueError("Unknown certificate type: '%s'" % s) |
| |
| if other.tlsIntoleranceType not in TLS_INTOLERANCE_TYPES: |
| raise ValueError( |
| "Unknown TLS intolerance type: '%s'" % other.tlsIntoleranceType) |
| |
| if other.minVersion > other.maxVersion: |
| raise ValueError("Versions set incorrectly") |
| |
| if not other.minVersion in ((3,0), (3,1), (3,2), (3,3)): |
| raise ValueError("minVersion set incorrectly") |
| |
| if not other.maxVersion in ((3,0), (3,1), (3,2), (3,3)): |
| raise ValueError("maxVersion set incorrectly") |
| |
| if other.maxVersion < (3,3): |
| # No sha256 pre TLS 1.2 |
| other.macNames = [e for e in self.macNames if e != "sha256"] |
| |
| return other |
| |
| def _getCertificateTypes(self): |
| l = [] |
| for ct in self.certificateTypes: |
| if ct == "x509": |
| l.append(CertificateType.x509) |
| else: |
| raise AssertionError() |
| return l |