Java tutorial
/* * Webauth Java - Java implementation of the University of Stanford WebAuth * protocol. * * Copyright (C) 2006 University of Oxford * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ package uk.ac.ox.webauth.crypto; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.InputStream; import java.io.IOException; import java.security.GeneralSecurityException; import java.security.SecureRandom; import java.security.spec.KeySpec; import java.util.Arrays; import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; import javax.crypto.spec.IvParameterSpec; import org.apache.commons.codec.binary.Hex; import org.bouncycastle.asn1.ASN1Encodable; import org.bouncycastle.asn1.ASN1InputStream; import uk.ac.ox.webauth.asn1.APOptions; import static javax.crypto.Cipher.DECRYPT_MODE; import static javax.crypto.Cipher.ENCRYPT_MODE; /** * Class implementing Kerberos encryption type 1, des-cbc-crc, as described in * section 6.2.3 of RFC 3961. * * <p/>$HeadURL$ * <br/>$LastChangedRevision$ * <br/>$LastChangedDate$ * <br/>$LastChangedBy$ * @author Mats Henrikson * @version $LastChangedRevision$ */ public class DesCbcCrc extends EType { private static final SecureRandom rand = new SecureRandom(); private static final int[] CRC_TABLE = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; private SecretKey key; public DesCbcCrc(SecretKey key) { this.key = key; } /** * From RFC 3961: * <pre> * +-----------+----------+---------+-----+ * |confounder | checksum | msg-seq | pad | * +-----------+----------+---------+-----+ * </pre> */ @Override public ASN1Encodable decrypt(byte[] cipherData) throws IOException, GeneralSecurityException { // decrypt the data Cipher cipher = Cipher.getInstance("DES/CBC/NoPadding"); IvParameterSpec iv = new IvParameterSpec(key.getEncoded()); cipher.init(DECRYPT_MODE, key, iv); byte[] data = cipher.doFinal(cipherData); // split out the CRC checksum (4 bytes) and check it byte[] checksum = new byte[4]; System.arraycopy(data, cipher.getBlockSize(), checksum, 0, checksum.length); Arrays.fill(data, cipher.getBlockSize(), cipher.getBlockSize() + checksum.length, (byte) 0); if (!Arrays.equals(checksum, modifiedCRC32(data))) { throw new GeneralSecurityException("Checksum failure."); } // return an ASN.1 object InputStream is = new ByteArrayInputStream(data); is.skip(cipher.getBlockSize() + checksum.length); ASN1InputStream ais = new ASN1InputStream(is); return (ASN1Encodable) ais.readObject(); } @Override public byte[] encrypt(ASN1Encodable o) throws IOException, GeneralSecurityException { // setup the Cipher so we can get the block size Cipher cipher = Cipher.getInstance("DES/CBC/NoPadding"); IvParameterSpec iv = new IvParameterSpec(key.getEncoded()); cipher.init(ENCRYPT_MODE, key, iv); int blockSize = cipher.getBlockSize(); // set up the byte array with data ByteArrayOutputStream baos = new ByteArrayOutputStream(); byte[] confounder = new byte[blockSize]; synchronized (rand) { rand.nextBytes(confounder); } baos.write(confounder); // write empty data in place of the checksum byte[] checksum = new byte[4]; baos.write(checksum); // write the message sequence baos.write(o.getDEREncoded()); // PKCS7 padding byte[] pad = new byte[blockSize - (baos.size() % blockSize)]; Arrays.fill(pad, (byte) pad.length); baos.write(pad); byte[] data = baos.toByteArray(); // calculate the checksum checksum = modifiedCRC32(data); System.arraycopy(checksum, 0, data, cipher.getBlockSize(), checksum.length); // now encrypt and return the data return cipher.doFinal(data); } private static byte[] modifiedCRC32(byte[] data) throws IOException { int crc = 0; for (int i = 0; i < data.length; i++) { crc = (crc >>> 8) ^ CRC_TABLE[(crc ^ data[i]) & 0xff]; } byte[] output = new byte[4]; for (int i = 0; i < 4; i++) { output[i] = (byte) ((crc >>> (i * 8)) & 0xff); } return output; } public static void main(String[] args) throws Exception { /* mod-crc-32 tests from RFC 3961 section A.5: mod-crc-32("foo") = 33 bc 32 73 mod-crc-32("test0123456789") = d6 88 3e b8 mod-crc-32("MASSACHVSETTS INSTITVTE OF TECHNOLOGY") = f7 80 41 e3 mod-crc-32(8000) = 4b 98 83 3b mod-crc-32(0008) = 32 88 db 0e mod-crc-32(0080) = 20 83 b8 ed mod-crc-32(80) = 20 83 b8 ed mod-crc-32(80000000) = 3b b6 59 ed mod-crc-32(00000001) = 96 30 07 77 */ test_modifiedCRC32(new String(Hex.encodeHex("foo".getBytes())), "33bc3273"); test_modifiedCRC32(new String(Hex.encodeHex("test0123456789".getBytes())), "d6883eb8"); test_modifiedCRC32(new String(Hex.encodeHex("MASSACHVSETTS INSTITVTE OF TECHNOLOGY".getBytes())), "f78041e3"); test_modifiedCRC32("8000", "4b98833b"); test_modifiedCRC32("0008", "3288db0e"); test_modifiedCRC32("0080", "2083b8ed"); test_modifiedCRC32("80", "2083b8ed"); test_modifiedCRC32("80000000", "3bb659ed"); test_modifiedCRC32("00000001", "96300777"); SecretKeyFactory factory = SecretKeyFactory.getInstance("DES"); KeySpec spec = new DESKeySpec(new byte[8]); SecretKey secretKey = factory.generateSecret(spec); ASN1Encodable apo = new APOptions(); DesCbcCrc dcc = new DesCbcCrc(secretKey); byte[] encrypted = dcc.encrypt(apo); apo = dcc.decrypt(encrypted); System.out.println("Encrypt-decrypt test successful."); } private static void test_modifiedCRC32(String hexData, String hexAnswer) throws Exception { System.out.println("Testing modified crc32 algorithm with data: " + hexData); System.out.println("Correct answer: " + hexAnswer); String answer = new String(Hex.encodeHex(modifiedCRC32(Hex.decodeHex(hexData.toCharArray())))); System.out.println("Answer: " + answer); if (hexAnswer.equalsIgnoreCase(answer)) { System.out.println("SUCCESS!"); } else { System.out.println("FAILURE!"); } } }