Decrypt in Golang what was encrypted in Python AES CFB

Question

Based on Golang CFB decryption documentation , I wrote a minimal working example for decrypting a string that was encrypted using AES CFB and then based on 64 encoded in python3.

Golang decryption works fine when a message has been encrypted in Golang (with the encryption function from the Golang doc example). However, when I encrypt a message in a python script using the python script package, I cannot successfully decrypt it in a golang script. I do not get the correct bytes.

$ python3 stack.py 
Going to encrypt and base64 "This is not encrypted" result:
b'jf9A5LCxKWPuNb1XiH+G3APAgR//'

Now going to call the Golang script:
b'Hello from Golang, going to decrypt: jf9A5LCxKWPuNb1XiH+G3APAgR//
Result:  Tl!\xca/\xf1\xc0\xb2\xd01Y\x02V\xec\xdf\xecy\xd38&\xd9\n'

Blocksize is used by default for both versions of AES.

So the question is: what is going wrong?

Golang script:

package main

import (
    "crypto/aes"
    "crypto/cipher"
    "encoding/base64"
    "fmt"
    "os"

)

func main() {
    key := []byte("TfvY7I358yospfWKcoviZizOShpm5hyH")
    iv := []byte("mb13KcoviZizvYhp")
    payload_python := os.Args[1]

    fmt.Println("Hello from Golang, going to decrypt: "+payload_python+" Result: "+string(decrypt(key, payload_python, iv)))
}


func decrypt(key []byte, cryptoText string, iv []byte) []byte {
    ciphertext, _ := base64.StdEncoding.DecodeString(cryptoText)    //decode base64 coding

    //prepare decryption based on key and iv
    block, _ := aes.NewCipher(key)
    stream := cipher.NewCFBDecrypter(block, iv)

    //decrypt
    stream.XORKeyStream(ciphertext, ciphertext)

    return ciphertext
}

Python script:

 #!/usr/bin/env python3
import base64
from Crypto.Cipher import AES
from subprocess import check_output


original_message = 'This is not encrypted'

key = 'TfvY7I358yospfWKcoviZizOShpm5hyH'
iv = 'mb13KcoviZizvYhp'

#prepare encryption
cfb_cipher_encrypt = AES.new(key, AES.MODE_CFB, iv)
#encrypt and base64 encode
encryptedpayload = base64.b64encode(cfb_cipher_encrypt.encrypt(original_message))

print('Going to encrypt and base64 "{}" result:\n{}\n'.format(original_message,encryptedpayload))

print('Now going to call the Golang script:')
print(check_output('go run stack.go {}'.format(encryptedpayload.decode()),shell=True))

Answer 1

Python .

Go .

 #!/usr/bin/env python3
import base64
from Crypto.Cipher import AES

MODE = AES.MODE_CFB
BLOCK_SIZE = 16
SEGMENT_SIZE = 128

def _pad_string(value):
    length = len(value)
    pad_size = BLOCK_SIZE - (length % BLOCK_SIZE)
    return value.ljust(length + pad_size, '\x00')

def encrypt(key, iv, plaintext):
    aes = AES.new(key, MODE, iv, segment_size=SEGMENT_SIZE)
    plaintext = _pad_string(plaintext)
    encrypted_text = aes.encrypt(plaintext)
    return encrypted_text

key = 'TfvY7I358yospfWKcoviZizOShpm5hyH'
iv = 'mb13KcoviZizvYhp'
original_message = 'This is not encrypted'

encryptedpayload = base64.b64encode(encrypt(key, iv, original_message))

print('Going to encrypt and base64 "{}" result:\n{}\n'.format(original_message,encryptedpayload))

: http://chase-seibert.imtqy.com/blog/2016/01/29/cryptojs-pycrypto-ios-aes256.html