1
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6
7 """Class for setting handshake parameters."""
8
9 from .constants import CertificateType
10 from .utils import cryptomath
11 from .utils import cipherfactory
12
13
14
15 CIPHER_NAMES = ["rc4", "aes256", "aes128", "3des"]
16 MAC_NAMES = ["sha", "sha256"]
17 CIPHER_IMPLEMENTATIONS = ["openssl", "pycrypto", "python"]
18 CERTIFICATE_TYPES = ["x509"]
19
21 """This class encapsulates various parameters that can be used with
22 a TLS handshake.
23 @sort: minKeySize, maxKeySize, cipherNames, macNames, certificateTypes,
24 minVersion, maxVersion
25
26 @type minKeySize: int
27 @ivar minKeySize: The minimum bit length for asymmetric keys.
28
29 If the other party tries to use SRP, RSA, or Diffie-Hellman
30 parameters smaller than this length, an alert will be
31 signalled. The default is 1023.
32
33 @type maxKeySize: int
34 @ivar maxKeySize: The maximum bit length for asymmetric keys.
35
36 If the other party tries to use SRP, RSA, or Diffie-Hellman
37 parameters larger than this length, an alert will be signalled.
38 The default is 8193.
39
40 @type cipherNames: list
41 @ivar cipherNames: The allowed ciphers, in order of preference.
42
43 The allowed values in this list are 'aes256', 'aes128', '3des', and
44 'rc4'. If these settings are used with a client handshake, they
45 determine the order of the ciphersuites offered in the ClientHello
46 message.
47
48 If these settings are used with a server handshake, the server will
49 choose whichever ciphersuite matches the earliest entry in this
50 list.
51
52 NOTE: If '3des' is used in this list, but TLS Lite can't find an
53 add-on library that supports 3DES, then '3des' will be silently
54 removed.
55
56 The default value is ['rc4', 'aes256', 'aes128', '3des'].
57
58 @type macNames: list
59 @ivar macNames: The allowed MAC algorithms.
60
61 The allowed values in this list are 'sha' and 'md5'.
62
63 The default value is ['sha'].
64
65
66 @type certificateTypes: list
67 @ivar certificateTypes: The allowed certificate types, in order of
68 preference.
69
70 The only allowed certificate type is 'x509'. This list is only used with a
71 client handshake. The client will advertise to the server which certificate
72 types are supported, and will check that the server uses one of the
73 appropriate types.
74
75
76 @type minVersion: tuple
77 @ivar minVersion: The minimum allowed SSL/TLS version.
78
79 This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for
80 TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a lower
81 version, a protocol_version alert will be signalled. The default is (3,1).
82
83 @type maxVersion: tuple
84 @ivar maxVersion: The maximum allowed SSL/TLS version.
85
86 This variable can be set to (3,0) for SSL 3.0, (3,1) for TLS 1.0, (3,2) for
87 TLS 1.1, or (3,3) for TLS 1.2. If the other party wishes to use a higher
88 version, a protocol_version alert will be signalled. The default is (3,3).
89 (WARNING: Some servers may (improperly) reject clients which offer support
90 for TLS 1.1. In this case, try lowering maxVersion to (3,1)).
91
92 @type useExperimentalTackExtension: bool
93 @ivar useExperimentalTackExtension: Whether to enabled TACK support.
94
95 Note that TACK support is not standardized by IETF and uses a temporary
96 TLS Extension number, so should NOT be used in production software.
97 """
99 self.minKeySize = 1023
100 self.maxKeySize = 8193
101 self.cipherNames = CIPHER_NAMES
102 self.macNames = MAC_NAMES
103 self.cipherImplementations = CIPHER_IMPLEMENTATIONS
104 self.certificateTypes = CERTIFICATE_TYPES
105 self.minVersion = (3,1)
106 self.maxVersion = (3,3)
107 self.useExperimentalTackExtension = False
108
109
110
112 other = HandshakeSettings()
113 other.minKeySize = self.minKeySize
114 other.maxKeySize = self.maxKeySize
115 other.cipherNames = self.cipherNames
116 other.macNames = self.macNames
117 other.cipherImplementations = self.cipherImplementations
118 other.certificateTypes = self.certificateTypes
119 other.minVersion = self.minVersion
120 other.maxVersion = self.maxVersion
121
122 if not cipherfactory.tripleDESPresent:
123 other.cipherNames = [e for e in self.cipherNames if e != "3des"]
124 if len(other.cipherNames)==0:
125 raise ValueError("No supported ciphers")
126 if len(other.certificateTypes)==0:
127 raise ValueError("No supported certificate types")
128
129 if not cryptomath.m2cryptoLoaded:
130 other.cipherImplementations = \
131 [e for e in other.cipherImplementations if e != "openssl"]
132 if not cryptomath.pycryptoLoaded:
133 other.cipherImplementations = \
134 [e for e in other.cipherImplementations if e != "pycrypto"]
135 if len(other.cipherImplementations)==0:
136 raise ValueError("No supported cipher implementations")
137
138 if other.minKeySize<512:
139 raise ValueError("minKeySize too small")
140 if other.minKeySize>16384:
141 raise ValueError("minKeySize too large")
142 if other.maxKeySize<512:
143 raise ValueError("maxKeySize too small")
144 if other.maxKeySize>16384:
145 raise ValueError("maxKeySize too large")
146 for s in other.cipherNames:
147 if s not in CIPHER_NAMES:
148 raise ValueError("Unknown cipher name: '%s'" % s)
149 for s in other.cipherImplementations:
150 if s not in CIPHER_IMPLEMENTATIONS:
151 raise ValueError("Unknown cipher implementation: '%s'" % s)
152 for s in other.certificateTypes:
153 if s not in CERTIFICATE_TYPES:
154 raise ValueError("Unknown certificate type: '%s'" % s)
155
156 if other.minVersion > other.maxVersion:
157 raise ValueError("Versions set incorrectly")
158
159 if not other.minVersion in ((3,0), (3,1), (3,2), (3,3)):
160 raise ValueError("minVersion set incorrectly")
161
162 if not other.maxVersion in ((3,0), (3,1), (3,2), (3,3)):
163 raise ValueError("maxVersion set incorrectly")
164
165 if other.maxVersion < (3,3):
166
167 other.macNames = [e for e in self.macNames if e != "sha256"]
168
169 return other
170
172 l = []
173 for ct in self.certificateTypes:
174 if ct == "x509":
175 l.append(CertificateType.x509)
176 else:
177 raise AssertionError()
178 return l
179