1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
#
# This file is part of pysnmp software.
#
# Copyright (c) 2005-2018, Olivier Verriest <verri@x25.pm>
# License: http://snmplabs.com/pysnmp/license.html
#
import hmac
try:
from hashlib import sha224
from hashlib import sha256
from hashlib import sha384
from hashlib import sha512
except ImportError:
class NotAvailable(object):
def __call__(self, *args, **kwargs):
raise errind.authenticationError
sha224 = sha256 = sha384 = sha512 = NotAvailable()
from pyasn1.type import univ
from pysnmp.proto.secmod.rfc3414.auth import base
from pysnmp.proto.secmod.rfc3414 import localkey
from pysnmp.proto import errind, error
# 7.2.4
class HmacSha2(base.AbstractAuthenticationService):
SHA224_SERVICE_ID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 4) # usmHMAC128SHA224AuthProtocol
SHA256_SERVICE_ID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 5) # usmHMAC192SHA256AuthProtocol
SHA384_SERVICE_ID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 6) # usmHMAC256SHA384AuthProtocol
SHA512_SERVICE_ID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 7) # usmHMAC384SHA512AuthProtocol
KEY_LENGTH = {
SHA224_SERVICE_ID: 28,
SHA256_SERVICE_ID: 32,
SHA384_SERVICE_ID: 48,
SHA512_SERVICE_ID: 64
}
DIGEST_LENGTH = {
SHA224_SERVICE_ID: 16,
SHA256_SERVICE_ID: 24,
SHA384_SERVICE_ID: 32,
SHA512_SERVICE_ID: 48
}
HASH_ALGORITHM = {
SHA224_SERVICE_ID: sha224,
SHA256_SERVICE_ID: sha256,
SHA384_SERVICE_ID: sha384,
SHA512_SERVICE_ID: sha512
}
IPAD = [0x36] * 64
OPAD = [0x5C] * 64
def __init__(self, oid):
if oid not in self.HASH_ALGORITHM:
raise error.ProtocolError('No SHA-2 authentication algorithm %s available' % (oid,))
self.__hashAlgo = self.HASH_ALGORITHM[oid]
self.__digestLength = self.DIGEST_LENGTH[oid]
self.__placeHolder = univ.OctetString((0,) * self.__digestLength).asOctets()
def hashPassphrase(self, authKey):
return localkey.hashPassphrase(authKey, self.__hashAlgo)
def localizeKey(self, authKey, snmpEngineID):
return localkey.localizeKey(authKey, snmpEngineID, self.__hashAlgo)
@property
def digestLength(self):
return self.__digestLength
# 7.3.1
def authenticateOutgoingMsg(self, authKey, wholeMsg):
# 7.3.1.1
location = wholeMsg.find(self.__placeHolder)
if location == -1:
raise error.ProtocolError('Can\'t locate digest placeholder')
wholeHead = wholeMsg[:location]
wholeTail = wholeMsg[location + self.__digestLength:]
# 7.3.1.2, 7.3.1.3
try:
mac = hmac.new(authKey.asOctets(), wholeMsg, self.__hashAlgo)
except errind.ErrorIndication as exc:
raise error.StatusInformation(errorIndication=exc)
# 7.3.1.4
mac = mac.digest()[:self.__digestLength]
# 7.3.1.5 & 6
return wholeHead + mac + wholeTail
# 7.3.2
def authenticateIncomingMsg(self, authKey, authParameters, wholeMsg):
# 7.3.2.1 & 2
if len(authParameters) != self.__digestLength:
raise error.StatusInformation(
errorIndication=errind.authenticationError
)
# 7.3.2.3
location = wholeMsg.find(authParameters.asOctets())
if location == -1:
raise error.ProtocolError('Can\'t locate digest in wholeMsg')
wholeHead = wholeMsg[:location]
wholeTail = wholeMsg[location + self.__digestLength:]
authenticatedWholeMsg = wholeHead + self.__placeHolder + wholeTail
# 7.3.2.4
try:
mac = hmac.new(authKey.asOctets(), authenticatedWholeMsg, self.__hashAlgo)
except errind.ErrorIndication as exc:
raise error.StatusInformation(errorIndication=exc)
# 7.3.2.5
mac = mac.digest()[:self.__digestLength]
# 7.3.2.6
if mac != authParameters:
raise error.StatusInformation(
errorIndication=errind.authenticationFailure
)
return authenticatedWholeMsg
|
