FlushBug.java

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/*
 * @test
 * @bug 0000000
 * @summary FlushBug
 * @author Jan Luehe
 * @key randomness
 */
import java.io.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;

public class FlushBug {
    public static void main(String[] args) throws Exception {
        SecureRandom sr = new SecureRandom();

        // Create new DES key.
        KeyGenerator kg = KeyGenerator.getInstance("DES", "SunJCE");
        kg.init(sr);
        Key key = kg.generateKey();

        // Generate an IV.
        byte[] iv_bytes = new byte[8];
        sr.nextBytes(iv_bytes);
        IvParameterSpec iv = new IvParameterSpec(iv_bytes);

        // Create the consumer
        Cipher decrypter = Cipher.getInstance("DES/CFB8/NoPadding", "SunJCE");
        decrypter.init(Cipher.DECRYPT_MODE, key, iv);
        PipedInputStream consumer = new PipedInputStream();
        InputStream in = new CipherInputStream(consumer, decrypter);

        // Create the producer
        Cipher encrypter = Cipher.getInstance("DES/CFB8/NoPadding", "SunJCE");
        encrypter.init(Cipher.ENCRYPT_MODE, key, iv);
        PipedOutputStream producer = new PipedOutputStream();
        OutputStream out = new CipherOutputStream(producer, encrypter);

        producer.connect(consumer); // connect pipe

        byte[] plaintext = "abcdef".getBytes();
        for (int i = 0; i < plaintext.length; i++) {
            out.write(plaintext[i]);
            out.flush();
            int b = in.read();
            String original = new String(plaintext, i, 1);
            String result = new String(new byte[] { (byte)b });
            System.out.println("  " + original + " -> " + result);
        }
    }
}