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8 """Class for setting handshake parameters."""
9
10 from .constants import CertificateType
11 from .utils import cryptomath
12 from .utils import cipherfactory
13
14
15
16 CIPHER_NAMES = ["rc4", "aes256", "aes128", "3des"]
17 MAC_NAMES = ["sha", "sha256"]
18 CIPHER_IMPLEMENTATIONS = ["openssl", "pycrypto", "python"]
19 CERTIFICATE_TYPES = ["x509"]
20
22 """This class encapsulates various parameters that can be used with
23 a TLS handshake.
24 @sort: minKeySize, maxKeySize, cipherNames, macNames, certificateTypes,
25 minVersion, maxVersion
26
27 @type minKeySize: int
28 @ivar minKeySize: The minimum bit length for asymmetric keys.
29
30 If the other party tries to use SRP, RSA, or Diffie-Hellman
31 parameters smaller than this length, an alert will be
32 signalled. The default is 1023.
33
34 @type maxKeySize: int
35 @ivar maxKeySize: The maximum bit length for asymmetric keys.
36
37 If the other party tries to use SRP, RSA, or Diffie-Hellman
38 parameters larger than this length, an alert will be signalled.
39 The default is 8193.
40
41 @type cipherNames: list
42 @ivar cipherNames: The allowed ciphers, in order of preference.
43
44 The allowed values in this list are 'aes256', 'aes128', '3des', and
45 'rc4'. If these settings are used with a client handshake, they
46 determine the order of the ciphersuites offered in the ClientHello
47 message.
48
49 If these settings are used with a server handshake, the server will
50 choose whichever ciphersuite matches the earliest entry in this
51 list.
52
53 NOTE: If '3des' is used in this list, but TLS Lite can't find an
54 add-on library that supports 3DES, then '3des' will be silently
55 removed.
56
57 The default value is ['rc4', 'aes256', 'aes128', '3des'].
58
59 @type macNames: list
60 @ivar macNames: The allowed MAC algorithms.
61
62 The allowed values in this list are 'sha' and 'md5'.
63
64 The default value is ['sha'].
65
66
67 @type certificateTypes: list
68 @ivar certificateTypes: The allowed certificate types, in order of
69 preference.
70
71 The only allowed certificate type is 'x509'. This list is only used with a
72 client handshake. The client will advertise to the server which certificate
73 types are supported, and will check that the server uses one of the
74 appropriate types.
75
76
77 @type minVersion: tuple
78 @ivar minVersion: The minimum allowed SSL/TLS version.
79
80 This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for
81 TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a lower
82 version, a protocol_version alert will be signalled. The default is (3,1).
83
84 @type maxVersion: tuple
85 @ivar maxVersion: The maximum allowed SSL/TLS version.
86
87 This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for
88 TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a higher
89 version, a protocol_version alert will be signalled. The default is (3,3).
90 (WARNING: Some servers may (improperly) reject clients which offer support
91 for TLS 1.1. In this case, try lowering maxVersion to (3,1)).
92
93 @type useExperimentalTackExtension: bool
94 @ivar useExperimentalTackExtension: Whether to enabled TACK support.
95
96 Note that TACK support is not standardized by IETF and uses a temporary
97 TLS Extension number, so should NOT be used in production software.
98 """
100 self.minKeySize = 1023
101 self.maxKeySize = 8193
102 self.cipherNames = CIPHER_NAMES
103 self.macNames = MAC_NAMES
104 self.cipherImplementations = CIPHER_IMPLEMENTATIONS
105 self.certificateTypes = CERTIFICATE_TYPES
106 self.minVersion = (3,1)
107 self.maxVersion = (3,3)
108 self.useExperimentalTackExtension = False
109
110
111
113 other = HandshakeSettings()
114 other.minKeySize = self.minKeySize
115 other.maxKeySize = self.maxKeySize
116 other.cipherNames = self.cipherNames
117 other.macNames = self.macNames
118 other.cipherImplementations = self.cipherImplementations
119 other.certificateTypes = self.certificateTypes
120 other.minVersion = self.minVersion
121 other.maxVersion = self.maxVersion
122
123 if not cipherfactory.tripleDESPresent:
124 other.cipherNames = [e for e in self.cipherNames if e != "3des"]
125 if len(other.cipherNames)==0:
126 raise ValueError("No supported ciphers")
127 if len(other.certificateTypes)==0:
128 raise ValueError("No supported certificate types")
129
130 if not cryptomath.m2cryptoLoaded:
131 other.cipherImplementations = \
132 [e for e in other.cipherImplementations if e != "openssl"]
133 if not cryptomath.pycryptoLoaded:
134 other.cipherImplementations = \
135 [e for e in other.cipherImplementations if e != "pycrypto"]
136 if len(other.cipherImplementations)==0:
137 raise ValueError("No supported cipher implementations")
138
139 if other.minKeySize<512:
140 raise ValueError("minKeySize too small")
141 if other.minKeySize>16384:
142 raise ValueError("minKeySize too large")
143 if other.maxKeySize<512:
144 raise ValueError("maxKeySize too small")
145 if other.maxKeySize>16384:
146 raise ValueError("maxKeySize too large")
147 for s in other.cipherNames:
148 if s not in CIPHER_NAMES:
149 raise ValueError("Unknown cipher name: '%s'" % s)
150 for s in other.cipherImplementations:
151 if s not in CIPHER_IMPLEMENTATIONS:
152 raise ValueError("Unknown cipher implementation: '%s'" % s)
153 for s in other.certificateTypes:
154 if s not in CERTIFICATE_TYPES:
155 raise ValueError("Unknown certificate type: '%s'" % s)
156
157 if other.minVersion > other.maxVersion:
158 raise ValueError("Versions set incorrectly")
159
160 if not other.minVersion in ((3,0), (3,1), (3,2), (3,3)):
161 raise ValueError("minVersion set incorrectly")
162
163 if not other.maxVersion in ((3,0), (3,1), (3,2), (3,3)):
164 raise ValueError("maxVersion set incorrectly")
165
166 if other.maxVersion < (3,3):
167
168 other.macNames = [e for e in self.macNames if e != "sha256"]
169
170 return other
171
173 l = []
174 for ct in self.certificateTypes:
175 if ct == "x509":
176 l.append(CertificateType.x509)
177 else:
178 raise AssertionError()
179 return l
180