Below is the code in my nodejs project to encrypt and decrypt the data which is working perfectly.. I need to decrypt this nodejs encrypted data using python.
encryptData(data) {
try {
var encryptionKey = CryptoJS.enc.Utf8.parse("SecretKey");
return CryptoJS.RC4Drop.encrypt(JSON.stringify(data), encryptionKey, {
drop: 3072 / 4
}).toString();
} catch (error) {
console.error(error);
}
},
decryptData(encrypted) {
try {
var encryptionKey = CryptoJS.enc.Utf8.parse("SecretKey");
const plainPass = CryptoJS.RC4Drop.decrypt(encrypted, encryptionKey, {
drop: 3072 / 4
}).toString(CryptoJS.enc.Utf8);
return plainPass;
} catch (error) {
console.error(error);
}
},
How do I implement this similar decryption functionality in python?
I tried below code but its not working.
def rc4_drop(key, data, drop_bytes):
# RC4 Encryption/Decryption
cipher = ARC4.new(key)
decrypted = cipher.decrypt(data)
# Apply drop functionality
if drop_bytes < len(decrypted):
return decrypted[drop_bytes:]
else:
return b''
def decrypt_data(encrypted_base64, key, drop_bytes):
try:
# Convert Base64-encoded encrypted data to bytes
encrypted_bytes = base64.b64decode(encrypted_base64)
print("Encrypted bytes:", encrypted_bytes)
# Convert the key to bytes
key_bytes = key.encode('utf-8')
print("Key bytes:", key_bytes)
# Decrypt data with RC4 and apply drop bytes
plaintext_bytes = rc4_drop(key_bytes, encrypted_bytes, drop_bytes)
print("Plaintext bytes after dropping:", plaintext_bytes)
# Convert bytes to string
return plaintext_bytes.decode('utf-8') if plaintext_bytes else ''
except Exception as e:
print(f"An error occurred: {e}")
return None
Sample input and output from the Javascript code:
Encryption of "Hello" results in base64 output RlxFVdR/FA==.
The way you are applying the drop functionality in Python doesn't make sense as you must drop the first drop_bytes bytes from the stream cipher's output before decrypting the data, whereas you are doing it afterwards. Although I haven't tested this, one simple way is to prepend the cipher with drop_bytes number of dummy bytes and throw away that many initial bytes of the decrypted result, i.e.
dummy = b' ' * drop_bytes
decrypted = cipher.decrypt(dummy + data)[drop_bytes:]
return decrypted
but as pointed out in a comment by Oliver in the Staging Ground, the cryptodome implementation of RC4 directly supports dropping bytes with the keyword argument drop, i.e.
cipher = ARC4.new(key, drop=drop_bytes)
return cipher.decrypt(data)