Java tutorial
/* * Copyright 2001-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; /** * Operations to simplifiy common {@link java.security.MessageDigest} tasks. * This class is thread safe. * * @author Apache Software Foundation */ public class DigestUtils { /** * Returns a MessageDigest for the given <code>algorithm</code>. * * @param algorithm * The MessageDigest algorithm name. * @return An MD5 digest instance. * @throws RuntimeException * when a {@link java.security.NoSuchAlgorithmException} is caught, */ static MessageDigest getDigest(String algorithm) { try { return MessageDigest.getInstance(algorithm); } catch (NoSuchAlgorithmException e) { throw new RuntimeException(e.getMessage()); } } /** * Returns an MD5 MessageDigest. * * @return An MD5 digest instance. * @throws RuntimeException * when a {@link java.security.NoSuchAlgorithmException} is caught, */ private static MessageDigest getMd5Digest() { return getDigest("MD5"); } /** * Returns an SHA digest. * * @return An SHA digest instance. * @throws RuntimeException * when a {@link java.security.NoSuchAlgorithmException} is caught, */ private static MessageDigest getShaDigest() { return getDigest("SHA"); } /** * Calculates the MD5 digest and returns the value as a 16 element * <code>byte[]</code>. * * @param data * Data to digest * @return MD5 digest */ public static byte[] md5(byte[] data) { return getMd5Digest().digest(data); } /** * Calculates the MD5 digest and returns the value as a 16 element * <code>byte[]</code>. * * @param data * Data to digest * @return MD5 digest */ public static byte[] md5(String data) { return md5(data.getBytes()); } /** * Calculates the MD5 digest and returns the value as a 32 character hex * string. * * @param data * Data to digest * @return MD5 digest as a hex string */ public static String md5Hex(byte[] data) { return new String(Hex.encodeHex(md5(data))); } /** * Calculates the MD5 digest and returns the value as a 32 character hex * string. * * @param data * Data to digest * @return MD5 digest as a hex string */ public static String md5Hex(String data) { return new String(Hex.encodeHex(md5(data))); } /** * Calculates the SHA digest and returns the value as a <code>byte[]</code>. * * @param data * Data to digest * @return SHA digest */ public static byte[] sha(byte[] data) { return getShaDigest().digest(data); } /** * Calculates the SHA digest and returns the value as a <code>byte[]</code>. * * @param data * Data to digest * @return SHA digest */ public static byte[] sha(String data) { return sha(data.getBytes()); } /** * Calculates the SHA digest and returns the value as a hex string. * * @param data * Data to digest * @return SHA digest as a hex string */ public static String shaHex(byte[] data) { return new String(Hex.encodeHex(sha(data))); } /** * Calculates the SHA digest and returns the value as a hex string. * * @param data * Data to digest * @return SHA digest as a hex string */ public static String shaHex(String data) { return new String(Hex.encodeHex(sha(data))); } } /* * Copyright 2001-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ /** * Hex encoder and decoder. * * @since 1.1 * @author Apache Software Foundation * @version $Id: Hex.java,v 1.13 2004/04/18 18:22:33 ggregory Exp $ */ class Hex { /** * Used building output as Hex */ private static final char[] DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; /** * Converts an array of characters representing hexidecimal values into an * array of bytes of those same values. The returned array will be half the * length of the passed array, as it takes two characters to represent any * given byte. An exception is thrown if the passed char array has an odd * number of elements. * * @param data * An array of characters containing hexidecimal digits * @return A byte array containing binary data decoded from the supplied char * array. * @throws DecoderException * Thrown if an odd number or illegal of characters is supplied */ public static byte[] decodeHex(char[] data) throws RuntimeException { int len = data.length; if ((len & 0x01) != 0) { throw new RuntimeException("Odd number of characters."); } byte[] out = new byte[len >> 1]; // two characters form the hex value. for (int i = 0, j = 0; j < len; i++) { int f = toDigit(data[j], j) << 4; j++; f = f | toDigit(data[j], j); j++; out[i] = (byte) (f & 0xFF); } return out; } /** * Converts a hexadecimal character to an integer. * * @param ch * A character to convert to an integer digit * @param index * The index of the character in the source * @return An integer * @throws DecoderException * Thrown if ch is an illegal hex character */ protected static int toDigit(char ch, int index) throws RuntimeException { int digit = Character.digit(ch, 16); if (digit == -1) { throw new RuntimeException("Illegal hexadecimal charcter " + ch + " at index " + index); } return digit; } /** * Converts an array of bytes into an array of characters representing the * hexidecimal values of each byte in order. The returned array will be double * the length of the passed array, as it takes two characters to represent any * given byte. * * @param data * a byte[] to convert to Hex characters * @return A char[] containing hexidecimal characters */ public static char[] encodeHex(byte[] data) { int l = data.length; char[] out = new char[l << 1]; // two characters form the hex value. for (int i = 0, j = 0; i < l; i++) { out[j++] = DIGITS[(0xF0 & data[i]) >>> 4]; out[j++] = DIGITS[0x0F & data[i]]; } return out; } /** * Converts an array of character bytes representing hexidecimal values into * an array of bytes of those same values. The returned array will be half the * length of the passed array, as it takes two characters to represent any * given byte. An exception is thrown if the passed char array has an odd * number of elements. * * @param array * An array of character bytes containing hexidecimal digits * @return A byte array containing binary data decoded from the supplied byte * array (representing characters). * @throws DecoderException * Thrown if an odd number of characters is supplied to this * function * @see #decodeHex(char[]) */ public byte[] decode(byte[] array) throws RuntimeException { return decodeHex(new String(array).toCharArray()); } /** * Converts a String or an array of character bytes representing hexidecimal * values into an array of bytes of those same values. The returned array will * be half the length of the passed String or array, as it takes two * characters to represent any given byte. An exception is thrown if the * passed char array has an odd number of elements. * * @param object * A String or, an array of character bytes containing hexidecimal * digits * @return A byte array containing binary data decoded from the supplied byte * array (representing characters). * @throws DecoderException * Thrown if an odd number of characters is supplied to this * function or the object is not a String or char[] * @see #decodeHex(char[]) */ public Object decode(Object object) throws RuntimeException { try { char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object; return decodeHex(charArray); } catch (ClassCastException e) { throw new RuntimeException(e.getMessage()); } } /** * Converts an array of bytes into an array of bytes for the characters * representing the hexidecimal values of each byte in order. The returned * array will be double the length of the passed array, as it takes two * characters to represent any given byte. * * @param array * a byte[] to convert to Hex characters * @return A byte[] containing the bytes of the hexidecimal characters * @see #encodeHex(byte[]) */ public byte[] encode(byte[] array) { return new String(encodeHex(array)).getBytes(); } /** * Converts a String or an array of bytes into an array of characters * representing the hexidecimal values of each byte in order. The returned * array will be double the length of the passed String or array, as it takes * two characters to represent any given byte. * * @param object * a String, or byte[] to convert to Hex characters * @return A char[] containing hexidecimal characters * @throws EncoderException * Thrown if the given object is not a String or byte[] * @see #encodeHex(byte[]) */ public Object encode(Object object) throws Exception { try { byte[] byteArray = object instanceof String ? ((String) object).getBytes() : (byte[]) object; return encodeHex(byteArray); } catch (ClassCastException e) { throw new RuntimeException(e.getMessage()); } } }