Develop Reference

How can I SHA1-HMAC a string in Python

I've been trying to figure out how to use HMAC to hash a string in Python for a TOTP generator I've already made in PHP. In PHP, I use the command echo -n "0x00000000035362f9" | xxd -r -p | openssl dgst -sha1 -mac HMAC -macopt hexkey:0080700040024c8581c2 which returns the desired value 7289e7b135d54b86a462a53da93ef6ad28b902f8. However, when I use the hmac library in Python 3.10
from hashlib import sha1
from hmac import new
key = "00000000035362f9"
msg = "0080700040024c8581c2"
byte_key = bytes(key, "UTF-8")
message = msg.encode()
print(new(byte_key, message, sha1).hexdigest())
print(new(message, byte_key, sha1).hexdigest())
The printed values are b05fe172b6a8a20767c18e1bfba159f0ea54c2bd and 0fe109b32b17aeff840255558e6b5c8ff3d8a115, neither match what I want.
I've tried making the key and message hex values first, I've made them raw bytes using b'0080700040024c8581c2', encoding them using UTF-8 and ASCII, and none of the solutions have worked.
I've looked at other post relating to this, and none of them worked.
Python hmac (sha1) calculation
Python HMAC OpenSSL equivalent
hmac returning different hexdigest values to openssl
Why Python and Node.js's HMAC result is different in this code?
Implementing SHA1-HMAC with Python

#jasonharper's answer from the comments was correct.
from hashlib import sha1
from hmac import new
from binascii import unhexlify
msg = unhexlify("00000000035362f9")
key = unhexlify("0080700040024c8581c2")
print(new(key, msg, sha1).hexdigest())

Packet Sniffer using Scapy

I have write code for sniffing packet using scapy in python. And i got some problems that make me confused, showed by this picture below.
enter image description here -> Important
so this is the code
import subprocess
import time
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
logging.getLogger("scapy.loading").setLevel(logging.ERROR)
logging.getLogger("scapy.interactive").setLevel(logging.ERROR)
try:
from scapy.all import *
except ImportError:
sys.exit()
interface = 'wlp10s0'
subprocess.call(["ifconfig",interface,"promisc"],stdout=None,stderr=None,shell=False)
print 'Interface has been set to Promiscous mode'
totalpackets=0
sniffingtime=10
protocols=0
infinite=1
def timenow():
currenttime=time.strftime("%m%d%y-%H%M%S")
return currenttime
def export():
p = sniff(iface='wlp10s0',timeout=sniffingtime,count=0)
wrpcap('./home/Desktop/' + timenow() + '.pcap',p);
while infinite==1 :
export()
I hope someone can helping me solve this code.
Thank you.

./home/... is an I valid path. Use /home/... instead.
It clearly says “OSerror: No such file or directory”. You may want to lookup those errors ;-)

hmac returning different hexdigest values to openssl

For example when I run this command in my terminal:
echo -n 'something' | openssl dgst -sha256 -hmac 'NhqPtmdS'
This is returned:
caa686a03a502a0da2985dfea0b0b5798657fc30c2fd917db527d29ea5b23579
I'm trying to do this in Python, but I don't know why is returning something different.
This is my code:
import base64
from hashlib import sha256
import hmac
key = base64.b64decode('NhqPtmdS')
jsonBytes = bytes('something', "ascii")
hmac_result = hmac.new(key, jsonBytes, sha256).hexdigest()
print(hmac_result)
But I'm getting the next result:
6a964bd560a9dc763864ddf337d64e5f2ef958e6937ad296084166da0db83eb9
Also I tried this:
hmac_result = hmac.new(key, jsonBytes, sha256)
base64.b64encode(hmac_result.digest()).decode()
But it's not working either.
Any advice will be appreciated.

Non-ASCII character '\x97' in file, but no encoding declared

I'm trying to encode the contents of a Python script in Linux. I just started off with a simple script called test.py -
# !/app/logs/Python/bin/python3
# -*- coding: ascii -*-
print ("hi")
Once I have the script, I execute the vim -x test.py and enter the encryption key twice. Then save the file as normal and then execute the script using python test.py
I tried almost all the examples provided in the link here but still i end up getting the below error -
SyntaxError: Non-ASCII character '\x97' in file test.py on line 1, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
I checked the default encoding using print sys.getdefaultencoding() and it is acsii.
What am i missing here. kindly clarify. I know this question is a duplicate but none of the solutions helped.

Python knows how to execute clear text Python source code. If you encrypt the source file, it no longer contains valid Python source and cannot be directly executed.
There are 2 possible ways here. First is to only obfuscate your source. You should be aware that obfuscation is not security, and a user could recover some Python source with some work (not necessarily the original source, because comments and doc strings could have been stripped off and variable names could have been changed). You could read How do I protect Python code? and google for python obfuscate to find some possible ways of obfuscating Python source and their trade-offs.
The good news with obfuscated source is that it can be used by anybody without any password.
Second way is to encrypt the source. If you use a decent tool, you can assume that it will be impossible to read or execute the file without knowing the key. In that sense, vim crypto has not the highest possible reputation. In the simplest way (for example with your example vim -x) you will have to decrypt the file to execute it. Unfortunately, good crypto modules are not shipped in a standard Python installation and must be downloaded from pypi. Well known crypto modules include pycrypto and cryptography.
You can then encrypt the most part of the code, and then at run time ask for the key, decrypt it and execute it. Still a serious job but feasible.
Alternatively, you could build in another language (C/C++) a decryptor that decrypts the remaining of the file and feed it into a python interpretor, but functionally, this is only a variant of the above method.
As per your comment I assume that you want to encrypt the source code and decrypt it (with the password) at run time. The princips are:
build a Python script that will take another arbitrary Python script, encode it with a secure crypto module and prepend it with some decrypting code.
at run time, the prepended code will ask for the password, decrypt the encrypted code exec it
The builder could be (this code uses the cryptography module):
import cryptography.fernet
import cryptography.hazmat.primitives.kdf.pbkdf2
import cryptography.hazmat.primitives.hashes
import cryptography.hazmat.backends
import base64
import os
import sys
# the encryption function
def encrypt_source(infile, outfile, passwd):
with open(infile, 'rb') as fdin: # read original file
plain_data = fdin.read()
salt, key = gen_key(passwd) # derive a key from the password
f = cryptography.fernet.Fernet(key)
crypted_data = f.encrypt(plain_data) # encrypt the original code
with open(outfile, "w") as fdout: # prepend a decoding block
fdout.write("""#! /usr/bin/env python
import cryptography.fernet
import cryptography.hazmat.primitives.kdf.pbkdf2
import cryptography.hazmat.primitives.hashes
import cryptography.hazmat.backends
import base64
import os
def gen_key(passwd, salt): # key derivation
kdf = cryptography.hazmat.primitives.kdf.pbkdf2.PBKDF2HMAC(
algorithm = cryptography.hazmat.primitives.hashes.SHA256(),
length = 32,
salt = salt,
iterations = 100000,
backend = cryptography.hazmat.backends.default_backend()
)
return base64.urlsafe_b64encode(kdf.derive(passwd))
passwd = input("Password:") # ask for the password
salt = base64.decodebytes({})
key = gen_key(passwd.encode(), salt) # derive the key from the password and the original salt
crypted_source = base64.decodebytes( # decode (base64) the crypted source
b'''{}'''
)
f = cryptography.fernet.Fernet(key)
plain_source = f.decrypt(crypted_source) # decrypt it
exec(plain_source) # and exec it
""".format(base64.encodebytes(salt),
base64.encodebytes(crypted_data).decode()))
# derive a key from a password and a random salt
def gen_key(passwd, salt=None):
if salt is None: salt = os.urandom(16)
kdf = cryptography.hazmat.primitives.kdf.pbkdf2.PBKDF2HMAC(
algorithm = cryptography.hazmat.primitives.hashes.SHA256(),
length = 32,
salt = salt,
iterations = 100000,
backend = cryptography.hazmat.backends.default_backend()
)
return salt, base64.urlsafe_b64encode(kdf.derive(passwd))
if __name__ == '__main__':
if len(sys.argv) != 3:
print("Usage {} infile outfile".format(sys.argv[0]))
sys.exit(1)
passwd = input("Password:").encode() # ask for a password
encrypt_source(sys.argv[1], sys.argv[2], passwd) # and generates an encrypted Python script

Python hashlib.md5 and ejabberd

I am using a python script as an external auth option in ejabberd 2.1.6.
I wanted to start encrypting the clear text passwords that come across in the auth verification, so that they are not being stored in plain text in the backend database. When I add the following code to my python script and restart ejabberd, it hangs:
import hashlib
clear = "barfoo"
salt = "foobar"
hash = hashlib.md5( salt + clear ).hexdigest()
Does hashlib require specific priviledges to run?
When I run it as a normal user (ejabberd) it works without issue. When the python script is run within the external auth of ejabberd it hangs.
I've attempted to have it write out the 'hash' to a file and it never gets there ... if i run it as the 'ejabberd' user, it writes out to file fine.
I've tried to find information about restrictions for using this library on ubuntu without any success. Any ideas?
-sd
** 22.02.2011: Here is the full script adapted from https://git.process-one.net/ejabberd/mainline/blobs/raw/2.1.x/doc/dev.html#htoc8 :
#!/usr/bin/python
import sys
from struct import *
import hashlib
def from_ejabberd():
input_length = sys.stdin.read(2)
(size,) = unpack('>h', input_length)
return sys.stdin.read(size).split(':')
def to_ejabberd(bool):
answer = 0
if bool:
answer = 1
token = pack('>hh', 2, answer)
sys.stdout.write(token)
sys.stdout.flush()
def auth(username, server, password):
clear = "barfoo"
salt = "foobar"
hash = hashlib.md5( salt + clear ).hexdigest()
if (password == hash): return True
else: return False
def isuser(username, server):
return True
def setpass(username, server, password):
return True
while True:
data = from_ejabberd()
success = False
if data[0] == "auth":
success = auth(data[1], data[2], data[3])
elif data[0] == "isuser":
success = isuser(data[1], data[2])
elif data[0] == "setpass":
success = setpass(data[1], data[2], data[3])
to_ejabberd(success)

I have been messing with the same problem. I Can't really track down the problem with openssl binings in _hashlib. Whatever the problem is, i will have to patch python distribution sources. Not really an feasible solution. So i ended up using a pycrypto wrapper for the crypto functions which don't block in this case.
pip install pycrypto
from Crypto.Hash import MD5
m = MD5.new()
m.update("%s%s" % (salt ,clear))
h.hexdigest()

I looked into the hashlib source and while it does not seem to require too much, it does import .so files as modules and one of them hits openssl. It all looks pretty safe but if ejabberd tries to fence itself against calls to 3rd party code (or if you have SELinux or something else to that effect running), stuff can conceivably get weird. I got this in a REPL:
>>> import _md5
>>> _md5.__file__
'/usr/lib/python2.7/lib-dynload/_md5module.so'
Try this on your box and then try putting
_md5 = imp.load_dynamic('_md5', '/usr/lib/python2.7/lib-dynload/_md5module.so')
Or just
import _md5
(with the appropriate path updated to yours) in your code before the offending line and with some trace statement afterwards. Try the same with _hashlib instead of _md5 (hashlib defaults to _hashlib which wraps openssl, but if it doesn't load or doesn't have the needed hash it falls back to _md5, _sha etc.). If it's not the imports that fail/hang then you can try calling _md5.new(salt + clear) and _hashlib.openssl_md5(salt + clear) and see if it's one of them.
If it is the import at fault, then possibly a similar problem was tackled here
I don't know ejabberd, so I can't relate their solution to your problem, unfortunately.
I do have to say it, though: in all python implementations I know, = instead of == in a condition would raise a SyntaxError and that's that - the program would never even enter the main while loop.

hashlib does not require anything special. What means hangs? Where does it hang? Use pdb.set_trace() to step trough the code or use 'strace' or 'ltrace' to investigate API calls.

Try to use logging module, it can help you to watch input and output data, also check scripts permissions, let executing by user which is ejabberd, or for debug just set chmod 777 external.py.