CFBTest

CFBTest.java

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.IvParameterSpec;

public class CFBTest
{
	final protected static char[] hexArray = "0123456789abcdef".toCharArray();
	public static String bytesToHex(byte[] bytes, int offset, int size) {
		char[] hexChars = new char[size * 2];
		for ( int j = 0; j < size; j++ ) {
			int v = bytes[offset+j] & 0xFF;
			hexChars[j * 2] = hexArray[v >>> 4];
			hexChars[j * 2 + 1] = hexArray[v & 0x0F];
		}
		return new String(hexChars);
	}

	public static void runMode (String mode) throws Exception
	{
		System.out.println("Testing Mode " + mode);
		byte [] keybytes = "1234567890123456".getBytes();
		System.out.println("Key: " + bytesToHex(keybytes, 0, 16));

		Cipher enc = Cipher.getInstance(mode);
		enc.init(Cipher.ENCRYPT_MODE,
				new SecretKeySpec(keybytes, "AES"),
				new IvParameterSpec(new byte[128/8]));

		Cipher dec = Cipher.getInstance(mode);
		dec.init(Cipher.ENCRYPT_MODE,
				new SecretKeySpec(keybytes, "AES"),
				new IvParameterSpec(new byte[128/8]));

		int [] sizes = new int [] {3,2,16,17};
		byte [] inbuf = "abcdefghijklmnopqrstuvwxyz".getBytes();
		byte [] buf1 = new byte [26];
		byte [] buf2 = new byte [26];
		for (int size : sizes) {
			System.out.println("plain: " + bytesToHex(inbuf, 0, size));
			int retsize = enc.update(inbuf, 0, size, buf1);
			System.out.println("enc:   " + bytesToHex(buf1, 0, retsize));
			retsize = dec.update(buf1, 0, retsize, buf2);
			System.out.println("dec:   " + bytesToHex(buf2, 0, retsize));
		}
		System.out.println();
	}

	public static void main (String [] args) throws Exception
	{
		runMode("AES/CTR/NoPadding");
		runMode("AES/CFB/NoPadding");
		runMode("AES/OFB/NoPadding");
	}
}

out.txt

Testing Mode AES/CTR/NoPadding
Key: 31323334353637383930313233343536
plain: 616263
enc:   b9d7fb
dec:   616263
plain: 6162
enc:   29a5
dec:   6162
plain: 6162636465666768696a6b6c6d6e6f70
enc:   066ef7d6fe32b55ff74411db5e61d8b9
dec:   6162636465666768696a6b6c6d6e6f70
plain: 6162636465666768696a6b6c6d6e6f7071
enc:   36e09f590281a4ce0e42b1cc99317f0628
dec:   6162636465666768696a6b6c6d6e6f7071

Testing Mode AES/CFB/NoPadding
Key: 31323334353637383930313233343536
plain: 616263
enc:   
dec:   
plain: 6162
enc:   
dec:   
plain: 6162636465666768696a6b6c6d6e6f70
enc:   b9d7fb29a5066ef7d6fe32b55ff74411
dec:   61626361626162636465666768696a6b
plain: 6162636465666768696a6b6c6d6e6f7071
enc:   e474ad5ef59d279526b95852fe021787
dec:   3679fbe7f172d5c42ca6eed243a9bdf4

Testing Mode AES/OFB/NoPadding
Key: 31323334353637383930313233343536
plain: 616263
enc:   
dec:   
plain: 6162
enc:   
dec:   
plain: 6162636465666768696a6b6c6d6e6f70
enc:   b9d7fb29a5066ef7d6fe32b55ff74411
dec:   61626361626162636465666768696a6b
plain: 6162636465666768696a6b6c6d6e6f7071
enc:   de50408811d0e22b8fd41caf5d1a8894
dec:   6c6d6e6f706162636465666768696a6b