AES 256-CFB in Node.js, Go, and Python

aes.go

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"io"
)

func keyEncrypt(keyStr string, cryptoText string) string {
	keyBytes := sha256.Sum256([]byte(keyStr))
	return encrypt(keyBytes[:], cryptoText)
}

// encrypt string to base64 crypto using AES
func encrypt(key []byte, text string) string {
	plaintext := []byte(text)

	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err)
	}

	// The IV needs to be unique, but not secure. Therefore it's common to
	// include it at the beginning of the ciphertext.
	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
	iv := ciphertext[:aes.BlockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		panic(err)
	}

	stream := cipher.NewCFBEncrypter(block, iv)
	stream.XORKeyStream(ciphertext[aes.BlockSize:], plaintext)

	return base64.StdEncoding.EncodeToString(ciphertext)
}

func keyDecrypt(keyStr string, cryptoText string) string {
	keyBytes := sha256.Sum256([]byte(keyStr))
	return decrypt(keyBytes[:], cryptoText)
}

// decrypt from base64 to decrypted string
func decrypt(key []byte, cryptoText string) string {
	ciphertext, err := base64.StdEncoding.DecodeString(cryptoText)
	if err != nil {
		panic(err)
	}

	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err)
	}

	// The IV needs to be unique, but not secure. Therefore it's common to
	// include it at the beginning of the ciphertext.
	if len(ciphertext) < aes.BlockSize {
		panic("ciphertext too short")
	}
	iv := ciphertext[:aes.BlockSize]
	ciphertext = ciphertext[aes.BlockSize:]
	stream := cipher.NewCFBDecrypter(block, iv)

	// XORKeyStream can work in-place if the two arguments are the same.
	stream.XORKeyStream(ciphertext, ciphertext)
	return fmt.Sprintf("%s", ciphertext)
}

func main() {
	encrypted := "lIR3JIHpomC5Zm8sjy29D/xFcXUX0c/4vQ=="

	fmt.Println(encrypted)
	fmt.Println(keyDecrypt("SecretKey", encrypted))
}

aes.js

'use strict';

const crypto = require('crypto');

const algorithm = 'aes-256-cfb';


function encryptText(keyStr, text) {
  const hash = crypto.createHash('sha256');
  hash.update(keyStr);
  const keyBytes = hash.digest();

  const iv = crypto.randomBytes(16);
  const cipher = crypto.createCipheriv(algorithm, keyBytes, iv);
  console.log('IV:', iv);
  let enc = [iv, cipher.update(text, 'utf8')];
  enc.push(cipher.final());
  return Buffer.concat(enc).toString('base64');
}

function decryptText(keyStr, text) {
  const hash = crypto.createHash('sha256');
  hash.update(keyStr);
  const keyBytes = hash.digest();

  const contents = Buffer.from(text, 'base64');
  const iv = contents.slice(0, 16);
  const textBytes = contents.slice(16);
  const decipher = crypto.createDecipheriv(algorithm, keyBytes, iv);
  let res = decipher.update(textBytes, '', 'utf8');
  res += decipher.final('utf8');
  return res;
} 

const encrypted = encryptText('SecretKey', 'It works!');
console.log('Encrypted: ', encrypted);

const decrypted = decryptText('SecretKey', encrypted);
console.log('Decrypted: ', decrypted);

aes.py

import base64
import hashlib
from Crypto.Cipher import AES
from Crypto import Random


def encrypt(keyStr, text):
    private_key = hashlib.sha256(keyStr.encode()).digest()
    rem = len(text) % 16
    padded = str.encode(text) + (b'\0' * (16 - rem)) if rem > 0 else str.encode(text)
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(private_key, AES.MODE_CFB, iv, segment_size=128)
    enc = cipher.encrypt(padded)[:len(text)]
    return base64.b64encode(iv + enc).decode()


def decrypt(keyStr, text):
    private_key = hashlib.sha256(keyStr.encode()).digest()
    text = base64.b64decode(text)
    iv, value = text[:16], text[16:]
    rem = len(value) % 16
    padded = value + (b'\0' * (16 - rem)) if rem > 0 else value
    cipher = AES.new(private_key, AES.MODE_CFB, iv, segment_size=128)
    return (cipher.decrypt(padded)[:len(value)]).decode()


def main():
    encrypted = 'lIR3JIHpomC5Zm8sjy29D/xFcXUX0c/4vQ=='
    print(encrypted)

    print(decrypt('SecretKey', encrypted))

if __name__== '__main__':
    main()