CryptoPAn.java

package org.araqne.log.api;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class CryptoPAn {
	public static class Mask {
		public long mask;
		public long pad;

		public Mask(long mask, long pad) {
			this.mask = mask;
			this.pad = pad;
		}
	}

	private Cipher cipher;
	private Mask[] masks;
	private String aesKey;
	private byte[] pad;

	public CryptoPAn(String key) {
		if (key.length() != 32) {
			throw new IllegalArgumentException("key must me a 32 byte long string");
		}

		this.aesKey = key.substring(0, 16);

		SecretKeySpec keyspec = new SecretKeySpec(aesKey.getBytes(), "AES");
		try {
			cipher = javax.crypto.Cipher.getInstance("AES/CBC/NoPadding");
			cipher.init(javax.crypto.Cipher.ENCRYPT_MODE, keyspec, new IvParameterSpec(new byte[16]));
			this.pad = cipher.doFinal(key.substring(16).getBytes());
			byte[] f4 = Arrays.copyOf(this.pad, 4);
			long f4bp = toInt(f4);

			this.masks = new Mask[32];
			for (int p = 0; p < 32; ++p) {
				long mask = 0xFFFFFFFFL >> (32 - p) << (32 - p);
				masks[p] = new Mask(mask, f4bp & (~mask));
			}
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (InvalidAlgorithmParameterException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		}

	}

	private long toInt(byte[] arr) {
		long l0 = ((long) arr[0] & 0xffL) << (8 * (3 - 0));
		long l1 = ((long) arr[1] & 0xffL) << (8 * (3 - 1));
		long l2 = ((long) arr[2] & 0xffL) << (8 * (3 - 2));
		long l3 = ((long) arr[3] & 0xffL) << (8 * (3 - 3));

		return l0 | l1 | l2 | l3;
	}

	public int[] anonymizei(String ip) {
		long result = 0;
		byte[] addria = new byte[4];
		{
			int i = 0;

			for (String a : ip.split("\\.")) {
				addria[i++] = (byte) Integer.parseInt(a.trim());
			}
			if (i != 4)
				throw new IllegalArgumentException("Invalid IPv4 address");
		}
		long addri = toInt(addria);

		long[] addresses = new long[32];
		for (int i = 0; i < this.masks.length; ++i) {
			addresses[i] = (addri & masks[i].mask) | masks[i].pad;
		}
		int[] calcResult = new int[32];
		try {
			for (int i = 0; i < 32; ++i) {
				calcResult[i] = calc(addresses[i]);
			}

			result = 0;
			for (int i = 0; i < 32; ++i) {
				result = (result << 1) | calcResult[i];
			}

			byte[] rarr = toArray(result ^ addri);
			int[] iresult = new int[4];
			iresult[0] = ((int) rarr[0]) & 0xff;
			iresult[1] = ((int) rarr[1]) & 0xff;
			iresult[2] = ((int) rarr[2]) & 0xff;
			iresult[3] = ((int) rarr[3]) & 0xff;
			return iresult;
		} catch (IllegalBlockSizeException e) {
			throw new IllegalStateException(e);
		} catch (BadPaddingException e) {
			throw new IllegalStateException(e);
		}
	}

	public String anonymize(String ip) {
		int[] result = anonymizei(ip);
		StringBuilder sb = new StringBuilder();
		sb.append(result[0]);
		sb.append(".");
		sb.append(result[1]);
		sb.append(".");
		sb.append(result[2]);
		sb.append(".");
		sb.append(result[3]);
		return sb.toString();
	}

	private byte[] toArray(long n) {
		byte[] result = new byte[4];
		for (int i = 3; i > -1; --i) {
			result[3 - i] = (byte) (n >> (i * 8) & 0xFF);
		}
		return result;
	}

	// calculate the first bit for Crypto-PAN
	private int calc(long a) throws IllegalBlockSizeException, BadPaddingException {
		pad[3] = (byte) (a & 0xFF);
		a >>= 8;
		pad[2] = (byte) (a & 0xFF);
		a >>= 8;
		pad[1] = (byte) (a & 0xFF);
		a >>= 8;
		pad[0] = (byte) (a & 0xFF);

		byte[] doFinal = cipher.doFinal(pad);

		return doFinal[0] < 0 ? 1 : 0;
	}

	public static void main(String[] args) throws InterruptedException {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < 32; ++i) {
			sb.append((char) i);
		}
		CryptoPAn c = new CryptoPAn(sb.toString());
		System.out.println(c.anonymize("192.0.2.2"));
		System.out.println(c.anonymize("192.0.2.1"));
		System.out.println(c.anonymize("192.0.3.1"));
		System.out.println(c.anonymize("192.1.2.1"));

		System.out.println(new CryptoPAn(sb.toString()).anonymize("192.0.2.1"));

		System.out.println("2.90.93.17".equals(c.anonymize("192.0.2.1")));
		long started = System.currentTimeMillis();
		for (int i = 0; i < 50000; ++i) {
			c.anonymize("192.0.2.1");
		}
		System.out.println("elapsed: " + (System.currentTimeMillis() - started));
	}
}