/usr/lib/python3/dist-packages/pysnmp/proto/secmod/rfc3414/priv/des.py is in python3-pysnmp4 4.2.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 | import random
from pysnmp.proto.secmod.rfc3414.priv import base
from pysnmp.proto.secmod.rfc3414.auth import hmacmd5, hmacsha
from pysnmp.proto.secmod.rfc3414 import localkey
from pysnmp.proto import errind, error
from pyasn1.type import univ
try:
from sys import version_info
except ImportError:
version_info = ( 0, 0 ) # a really early version
try:
from Crypto.Cipher import DES
except ImportError:
DES = None
random.seed()
# 8.2.4
class Des(base.AbstractEncryptionService):
serviceID = (1, 3, 6, 1, 6, 3, 10, 1, 2, 2) # usmDESPrivProtocol
if version_info < (2, 3):
_localInt = int(random.random()*0xffffffff)
else:
_localInt = random.randrange(0, 0xffffffff)
def hashPassphrase(self, authProtocol, privKey):
if authProtocol == hmacmd5.HmacMd5.serviceID:
return localkey.hashPassphraseMD5(privKey)
elif authProtocol == hmacsha.HmacSha.serviceID:
return localkey.hashPassphraseSHA(privKey)
else:
raise error.ProtocolError(
'Unknown auth protocol %s' % (authProtocol,)
)
def localizeKey(self, authProtocol, privKey, snmpEngineID):
if authProtocol == hmacmd5.HmacMd5.serviceID:
localPrivKey = localkey.localizeKeyMD5(privKey, snmpEngineID)
elif authProtocol == hmacsha.HmacSha.serviceID:
localPrivKey = localkey.localizeKeySHA(privKey, snmpEngineID)
else:
raise error.ProtocolError(
'Unknown auth protocol %s' % (authProtocol,)
)
return localPrivKey[:32] # key+IV
# 8.1.1.1
def __getEncryptionKey(self, privKey, snmpEngineBoots):
desKey = privKey[:8]
preIV = privKey[8:16]
securityEngineBoots = int(snmpEngineBoots)
salt = [
securityEngineBoots>>24&0xff,
securityEngineBoots>>16&0xff,
securityEngineBoots>>8&0xff,
securityEngineBoots&0xff,
self._localInt>>24&0xff,
self._localInt>>16&0xff,
self._localInt>>8&0xff,
self._localInt&0xff
]
if self._localInt == 0xffffffff:
self._localInt = 0
else:
self._localInt = self._localInt + 1
return desKey.asOctets(), \
univ.OctetString(salt).asOctets(), \
univ.OctetString(map(lambda x,y:x^y,salt,preIV.asNumbers())).asOctets()
def __getDecryptionKey(self, privKey, salt):
return privKey[:8].asOctets(), univ.OctetString(
map(lambda x,y:x^y, salt.asNumbers(), privKey[8:16].asNumbers())
).asOctets()
# 8.2.4.1
def encryptData(self, encryptKey, privParameters, dataToEncrypt):
if DES is None:
raise error.StatusInformation(
errorIndication=errind.encryptionError
)
snmpEngineBoots, snmpEngineTime, salt = privParameters
# 8.3.1.1
desKey, salt, iv = self.__getEncryptionKey(
encryptKey, snmpEngineBoots
)
# 8.3.1.2
privParameters = univ.OctetString(salt)
# 8.1.1.2
desObj = DES.new(desKey, DES.MODE_CBC, iv)
plaintext = dataToEncrypt + univ.OctetString((0,) * (8 - len(dataToEncrypt) % 8)).asOctets()
ciphertext = desObj.encrypt(plaintext)
# 8.3.1.3 & 4
return univ.OctetString(ciphertext), privParameters
# 8.2.4.2
def decryptData(self, decryptKey, privParameters, encryptedData):
if DES is None:
raise error.StatusInformation(
errorIndication=errind.decryptionError
)
snmpEngineBoots, snmpEngineTime, salt = privParameters
# 8.3.2.1
if len(salt) != 8:
raise error.StatusInformation(
errorIndication=errind.decryptionError
)
# 8.3.2.2 noop
# 8.3.2.3
desKey, iv = self.__getDecryptionKey(decryptKey, salt)
# 8.3.2.4 -> 8.1.1.3
if len(encryptedData) % 8 != 0:
raise error.StatusInformation(
errorIndication=errind.decryptionError
)
desObj = DES.new(desKey, DES.MODE_CBC, iv)
# 8.3.2.6
return desObj.decrypt(encryptedData.asOctets())
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