Difference between AES and Twofish

Introduction

Crypto algorithms are classified into two major categories: block ciphers and stream ciphers. Block ciphers are algorithms that transform the plaintext message into a cipher text message. Stream ciphers, on the other hand, encrypt each byte of data in the plaintext one at a time.

There are many block ciphers available in the market. In this article, we will talk about two very popular encryption algorithms, AES and Twofish. We will discuss their similarities, differences, and which one should be used to encrypt data.

AES

AES stands for Advanced Encryption Standard which is widely used in applications that require encryption. It was adopted by NIST (National Institute of Standards and Technology) as a standard in 2002.

AES is a symmetric key encryption algorithm, which means that both the sender and the receiver use the same key to encrypt and decrypt data. AES uses block cipher encryption, which means that it divides the plaintext into fixed-length blocks and encrypts each block with a separate key.

AES has different key lengths, including 128-bit, 192-bit, and 256-bit. The 128-bit key is the most commonly used key for encryption. The key length determines the security level of an encryption. A longer key length provides a higher level of security.

Here is sample code of AES encryption in Python:

from Crypto.Cipher import AES

key = b'1234567890123456'
plaintext = b'Hello World!'

cipher = AES.new(key, AES.MODE_EAX)
ciphertext, tag = cipher.encrypt_and_digest(plaintext)

print(ciphertext)

The above code is written in Python, which uses the PyCryptodome library. The AES encryption algorithm is used to encrypt the plaintext “Hello World!” with the 128-bit key “1234567890123456.”

Twofish

Twofish is another symmetric key encryption algorithm that was also considered by NIST before selecting AES. It was designed in 1998 by Bruce Schneier and is known for its flexibility, efficiency, and security.

Like AES, Twofish uses block cipher encryption and symmetric key encryption. It also supports different key lengths, including 128-bit, 192-bit, and 256-bit. The 128-bit key is the most commonly used key in Twofish encryption.

Here is sample code of Twofish encryption in Java:

import org.bouncycastle.crypto.engines.TwofishEngine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;

public static byte[] encrypt(byte[] key, byte[] iv, byte[] plaintext) {
    PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(
        new CBCBlockCipher(new TwofishEngine())
    );

    KeyParameter keyParam = new KeyParameter(key);
    ParametersWithIV ivParam = new ParametersWithIV(keyParam, iv);

    cipher.init(true, ivParam);
    byte[] output = new byte[cipher.getOutputSize(plaintext.length)];
    int processLength = cipher.processBytes(plaintext, 0, plaintext.length, output, 0);
    try {
        cipher.doFinal(output, processLength);
    } catch (org.bouncycastle.crypto.DataLengthException |
             org.bouncycastle.crypto.InvalidCipherTextException exception) {
        System.out.println(exception.getMessage());
    }

    return output;
}

The above code is in Java using Bouncy Castle library. The code uses Twofish encryption algorithm to encrypt the plaintext “Hello World!” with a 128-bit key and an initialization vector.

Differences between AES and Twofish

Even though both AES and Twofish are block cipher encryption algorithms and use symmetric key encryption, there are differences in how they handle encryption and decryption.

One difference is in their key schedule. AES uses a fixed key schedule, while Twofish uses a variable key schedule that can adapt to any key length. This means that Twofish is more flexible when it comes to key lengths compared to AES.

Another difference is in how they handle data. AES encrypts data in 128-bit blocks, while Twofish encrypts data in 128, 192, or 256-bit blocks based on the key length used. This means that Twofish can handle larger data blocks than AES.

Finally, AES is more commonly used and better supported in hardware, making it faster than Twofish. However, Twofish is still considered to be more secure than AES due to its variable key schedule.

Conclusion

Both AES and Twofish are capable encryption algorithms that provide a high level of security. The choice of which one to use depends on the specific needs of the application.

AES is the go-to choice when speed is a factor, and compatibility with hardware is essential. Twofish is the better choice when security is the primary concern, especially when handling large blocks of data.

In the end, it is essential to choose the encryption algorithm based on the security requirements of the system or application. There is no one-size-fits-all solution for encryption, and both AES and Twofish have their strengths and weaknesses.