Python TripleDES decryption

Question

I'm trying to decrypt a string in python encrypted using 3DES. It is encrypted by VB.net by my formal mate. I have no idea what is going on. The partial code in VB.net is

Private key() As Byte = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24}
Private iv() As Byte = {65, 110, 68, 26, 69, 178, 200, 219}
Private objTripleDES As New clsTripleDES(key, iv)

The code is similar is to https://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=1564&lngWId=10

Is it possible to decrypt in python? Do I need to use bytearray?

Take a look on [pyDes lib](http://twhiteman.netfirms.com/des.html) — Raskayu, Aug 10 '16 at 09:24

score 0 · Accepted Answer · answered Aug 12 '16 at 00:43

How about something like this:

from Crypto.Cipher import DES3

key = [
     1,  2,  3,  4,  5,  6,  7,  8, 
     9, 10, 11, 12, 13, 14, 15, 16, 
     17, 18, 19, 20, 21, 22, 23, 24
]

iv = [65, 110, 68, 26, 69, 178, 200, 219]

keyStr = ""
ivStr = ""

for i in key: 
    keyStr += chr(i)

for i in iv: 
    ivStr += chr(i)

encr = DES3.new(keyStr, DES3.MODE_CBC, ivStr)
decr = DES3.new(keyStr, DES3.MODE_CBC, ivStr)

#Outputs "1234567891234567"
print decr.decrypt(encr.encrypt("1234567891234567"))

You should investigate what mode was used for encryption in VB code. CBC is the default mode, according to this, but you can't be sure. See this when you figure out what mode was used.

Python TripleDES decryption

1 Answers1