I have following python code for AES decryption using pycryptodome, and which I verified and working.
key = "password"
key = hashlib.sha256(key.encode("utf-8")).digest()
iv = b'This is an IV456' #Random.new().read(AES.block_size)
iv_int = int(binascii.hexlify(iv), 16) # Convert the IV to a Python integer.
ctr = Counter.new(AES.block_size * 8, initial_value=iv_int) # Create a new Counter object with IV = iv_int.
aes = AES.new(key, AES.MODE_CTR, counter=ctr)
decryptData = aes.decrypt(encryptedData) # Decrypt and return the plaintext.
Now I need to convert this code in python using CryptoJS, I have done some coding but no idea how counter ctr
generated.
var i8a = new Uint8Array(data);
var password = "password";
var key = CryptoJS.SHA256(password);
var input = CryptoJS.lib.WordArray.create(i8a);
var output =CryptoJS.AES.decrypt(input, key, { mode: CryptoJS.mode.CTR});
var str = output.toString(CryptoJS.enc.Base64);
But the str
is always none.
Edit:
Based on below comment I have added iv
and noPadding option with config but still the decrypt return empty.
var iv = "112197289293498629157884805399637669174";
//iv = CryptoJS.enc.Base64.parse(iv); //enable this doesn't make any changes.
var output =CryptoJS.AES.decrypt(input, key,{ mode: CryptoJS.mode.CTR,iv:iv,padding: CryptoJS.pad.NoPadding});
Where I got the iv value from python side iv_int
.
And cannot remove the counter
from python script where I am getting error like,
'counter' keyword parameter is required with CTR mode
Note: I am sending the encrypted data from python to js through webRTC data channel.
Edit2:
The encrypt code in python which I actually used in python,
def encrypt(row):
key = "password"
key = hashlib.sha256(key.encode("utf-8")).digest()
iv = b'This is an IV456' #Random.new().read(AES.block_size)
iv_int = int(binascii.hexlify(iv), 16)
ctr = Counter.new(AES.block_size * 8, initial_value=iv_int)
cipher = AES.new(self.key, AES.MODE_CTR,counter=ctr)
return base64.b64encode(cipher.encrypt(raw))
Input data for encryption
fp = open(filepathFull, "rb")
while (True) and not done_reading:
data = fp.read(16384)
encrypted = encrypt(data)
sendWebrtcDataChannel(encrypted)
The following changes are necessary in the CryptoJS code:
decrypt
.decrypt
expects the ciphertext as CipherParams
object.decrypt
. Since the CTR mode does not use padding, mode and padding must be specified.The following JavaScript code is identical to the Python code:
// Testdata: Ciphertext as Array
var data = [0xa6, 0x8a, 0x3c, 0x0d, 0xeb, 0x9a, 0xfc, 0x9d, 0xb1, 0x83, 0xb0, 0x47, 0x9c, 0x63, 0x65, 0x1d, 0x16, 0x6e, 0x53, 0xac, 0xf4, 0xda, 0x0f, 0xac, 0xe3, 0x56, 0xf4, 0xfe, 0x2e, 0xf5, 0x1a, 0x19, 0xd5, 0x50, 0x5f, 0x1a, 0x85, 0x34, 0x6c, 0xac, 0x47, 0xd6, 0x2c];
var i8a = new Uint8Array(data);
var password = "password";
var key = CryptoJS.SHA256(password);
var iv = CryptoJS.enc.Latin1.parse("This is an IV456"); // Parse the IV with Latin1 encoder
//var iv = CryptoJS.enc.Hex.parse('5468697320697320616e204956343536'); // or with Hex encoder
var input = CryptoJS.lib.WordArray.create(i8a);
var output = CryptoJS.AES.decrypt(
{
ciphertext: input // Pass the ciphertext as CipherParams object
},
key,
{
iv: iv, // Pass IV
mode: CryptoJS.mode.CTR, // Specify mode
padding: CryptoJS.pad.NoPadding // Specify padding
});
var str = output.toString(CryptoJS.enc.Base64);
console.log(str);
var str = output.toString(CryptoJS.enc.Utf8);
console.log(str);
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.0.0/crypto-js.min.js"></script>
If in the Python code
encryptedData = binascii.unhexlify("a68a3c0deb9afc9db183b0479c63651d166e53acf4da0face356f4fe2ef51a19d5505f1a85346cac47d62c")
is used for the ciphertext, the same plaintext results.