EME for Java

This is a port of EME for Go.

EME (ECB-Mix-ECB or, clearer, Encrypt-Mix-Encrypt) is a wide-block encryption mode developed by Halevi and Rogaway in 2003.

EME uses multiple invocations of a block cipher to construct a new cipher of bigger block size (in multiples of 16 bytes, up to 2048 bytes).

Quoting from the original paper:

We describe a block-cipher mode of operation, EME, that turns an n-bit block cipher into a tweakable enciphering scheme that acts on strings of mn bits, where m ∈ [1..n]. The mode is parallelizable, but as serial-efficient as the non-parallelizable mode CMC [6]. EME can be used to solve the disk-sector encryption problem. The algorithm entails two layers of ECB encryption and a “lightweight mixing” in between. We prove EME secure, in the reduction-based sense of modern cryptography.

This is an implementation of EME in Java, complete with test vectors from IEEE and Halevi.

It has no dependencies outside the standard library.

Usage

Maven:

<dependency>
    <groupId>com.github.alexey-lapin.eme-cipher</groupId>
    <artifactId>eme-cipher</artifactId>
    <version>0.2.0</version>
</dependency>

Gradle:

implementation("com.github.alexey-lapin.eme-cipher:eme-cipher:0.2.0")

As a javax.crypto.Cipher

import com.github.alexeylapin.eme.cipher.AES128EMEProvider;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Security;

public class Example {

    public static void main(String[] args) throws Exception {
        // register eme provider
        Security.addProvider(new AES128EMEProvider());

        // create cipher
        Cipher cipher = Cipher.getInstance("AES/EME/PKCS7Padding");

        // initialize cipher
        byte[] key = new byte[32];
        SecretKeySpec keySpec = new SecretKeySpec(key, "AES");

        byte[] iv = new byte[16];
        cipher.init(Cipher.ENCRYPT_MODE, keySpec, new IvParameterSpec(iv));

        // use cipher
        byte[] data = new byte[100];
        byte[] encrypted = cipher.update(data);
    }
    
}

As a custom impl

import com.github.alexeylapin.eme.EME;

public class Example {

    public static void main(String[] args) throws Exception {
        // initialize cipher
        byte[] key = new byte[32];
        
        EME eme = EME.fromKey(key);
        
        byte[] iv = new byte[16];

        // use cipher
        byte[] data = new byte[512];
        byte[] encrypted = eme.encrypt(iv, data);
    }
    
}