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China and the SM Ciphers: Here’s SM4

And, so, NIST has defined AES as the standard for symmetric key encryption. But, NIST was pinpointed in possibly pushing a cipher with an NSA backdoor. For companies in China, the ShāngMì (SM) series of ciphers provide one alternative for TLS 1.3 integration and Wireless authentication. SM2 defines authentication, SM3 defines a hashing function, and SM4 for encryption. SM4 was developed by Lü Shuwang in 2007 and became a national standard (GB/T 32907–2016) in 2016. It has also been defined in RFC 8998 [here]:

With the SM4 cipher, we have a block size of 128 bits and a 128-bit encryption key. Each block of data has 32 rounds of processing. Overall, we can add a salt value of 128 bits in an IV (Initialisation Vector).

We can code with [here]:

import os
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
import sys

message="Hello"

keysize=16
iv = os.urandom(16)
mode=0

if (len(sys.argv)>1):
 message=str(sys.argv[1])
if (len(sys.argv)>2):
 mode=int(sys.argv[2])

key = os.urandom(keysize)

padder = padding.PKCS7(128).padder()

unpadder = padding.PKCS7(128).unpadder()

cipher=None

if…