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#
# This file is part of pysnmp software.
#
# Copyright (c) 2005-2020, Ilya Etingof <etingof@gmail.com>
# License: https://www.pysnmp.com/pysnmp/license.html
#
from hashlib import md5, sha1
from pyasn1.type import univ
def hash_passphrase(passphrase, hashFunc) -> univ.OctetString:
"""Return hash of passphrase using hashFunc hash function."""
passphrase = univ.OctetString(passphrase).asOctets()
# noinspection PyDeprecation,PyCallingNonCallable
hasher = hashFunc()
ringBuffer = passphrase * (64 // len(passphrase) + 1)
# noinspection PyTypeChecker
ringBufferLen = len(ringBuffer)
count = 0
mark = 0
while count < 16384:
e = mark + 64
if e < ringBufferLen:
hasher.update(ringBuffer[mark:e])
mark = e
else:
hasher.update(
ringBuffer[mark:ringBufferLen] + ringBuffer[0 : e - ringBufferLen]
)
mark = e - ringBufferLen
count += 1
digest = hasher.digest()
return univ.OctetString(digest)
def password_to_key(passphrase, snmpEngineId, hashFunc) -> univ.OctetString:
"""Return key from password."""
return localize_key(hash_passphrase(passphrase, hashFunc), snmpEngineId, hashFunc)
def localize_key(passKey, snmpEngineId, hashFunc) -> univ.OctetString:
"""Localize passKey with snmpEngineId using hashFunc hash function."""
passKey = univ.OctetString(passKey).asOctets()
# noinspection PyDeprecation,PyCallingNonCallable
digest = hashFunc(passKey + snmpEngineId.asOctets() + passKey).digest()
return univ.OctetString(digest)
# RFC3414: A.2.1
def hash_passphrase_md5(passphrase) -> univ.OctetString:
"""Return MD5 hash of passphrase."""
return hash_passphrase(passphrase, md5)
# RFC3414: A.2.2
def hash_passphrase_sha(passphrase) -> univ.OctetString:
"""Return SHA-1 hash of passphrase."""
return hash_passphrase(passphrase, sha1)
def password_to_key_md5(passphrase, snmpEngineId) -> univ.OctetString:
"""Return MD5 key from password."""
return localize_key(hash_passphrase_md5(passphrase), snmpEngineId, md5)
def password_to_key_sha(passphrase, snmpEngineId) -> univ.OctetString:
"""Return SHA-1 key from password."""
return localize_key(hash_passphrase_sha(passphrase), snmpEngineId, sha1)
def localize_key_md5(passKey, snmpEngineId) -> univ.OctetString:
"""Localize passKey with snmpEngineId using MD5 hash function."""
return localize_key(passKey, snmpEngineId, md5)
def localize_key_sha(passKey, snmpEngineId) -> univ.OctetString:
"""Localize passKey with snmpEngineId using SHA1 hash function."""
return localize_key(passKey, snmpEngineId, sha1)
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