Java tutorial
/* * JBoss DNA (http://www.jboss.org/dna) * See the COPYRIGHT.txt file distributed with this work for information * regarding copyright ownership. Some portions may be licensed * to Red Hat, Inc. under one or more contributor license agreements. * See the AUTHORS.txt file in the distribution for a full listing of * individual contributors. * * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA * is licensed to you 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. * * JBoss DNA 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 software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. */ import java.io.BufferedInputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; /** * @author Randall Hauch */ public class SecureHash { /** * Commonly-used hashing algorithms. */ public enum Algorithm { MD2("MD2", "The MD2 message digest algorithm as defined in RFC 1319"), MD5("MD5", "The MD5 message digest algorithm as defined in RFC 1321"), SHA_1("SHA-1", "The Secure Hash Algorithm, as defined in Secure Hash Standard, NIST FIPS 180-1"), SHA_256( "SHA-256", "New hash algorithms for which the draft Federal Information Processing Standard 180-2, " + "Secure Hash Standard (SHS) is now available. SHA-256 is a 256-bit hash function intended to provide 128 bits of " + "security against collision attacks."), SHA_384( "SHA-384", "New hash algorithms for which the draft Federal Information Processing Standard 180-2, " + "Secure Hash Standard (SHS) is now available. A 384-bit hash may be obtained by truncating the SHA-512 output."), SHA_512( "SHA-512", "New hash algorithms for which the draft Federal Information Processing Standard 180-2, " + "Secure Hash Standard (SHS) is now available. SHA-512 is a 512-bit hash function intended to provide 256 bits of security."); private String name; private String description; private Algorithm(String name, String description) { this.name = name; this.description = description; } public String digestName() { return this.name; } public String description() { return this.description; } @Override public String toString() { return digestName(); } } /** * Get the hash of the supplied content, using the supplied digest algorithm. * * @param algorithm the hashing function algorithm that should be used * @param content the content to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found * @throws IllegalArgumentException if the algorithm is null */ public static byte[] getHash(Algorithm algorithm, byte[] content) throws NoSuchAlgorithmException { return getHash(algorithm.digestName(), content); } /** * Get the hash of the supplied content, using the supplied digest algorithm. * * @param algorithm the hashing function algorithm that should be used * @param file the file containing the content to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found * @throws IllegalArgumentException if the algorithm is null * @throws IOException if there is an error reading the file */ public static byte[] getHash(Algorithm algorithm, File file) throws NoSuchAlgorithmException, IOException { return getHash(algorithm.digestName(), file); } /** * Get the hash of the supplied content, using the supplied digest algorithm. * * @param algorithm the hashing function algorithm that should be used * @param stream the stream containing the content to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found * @throws IllegalArgumentException if the algorithm is null * @throws IOException if there is an error reading the stream */ public static byte[] getHash(Algorithm algorithm, InputStream stream) throws NoSuchAlgorithmException, IOException { return getHash(algorithm.digestName(), stream); } /** * Get the hash of the supplied content, using the digest identified by the supplied name. * * @param digestName the name of the hashing function (or {@link MessageDigest message digest}) that should be used * @param content the content to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found */ public static byte[] getHash(String digestName, byte[] content) throws NoSuchAlgorithmException { MessageDigest digest = MessageDigest.getInstance(digestName); assert digest != null; return digest.digest(content); } /** * Get the hash of the supplied content, using the digest identified by the supplied name. * * @param digestName the name of the hashing function (or {@link MessageDigest message digest}) that should be used * @param file the file whose content is to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found * @throws IOException if there is an error reading the file */ public static byte[] getHash(String digestName, File file) throws NoSuchAlgorithmException, IOException { MessageDigest digest = MessageDigest.getInstance(digestName); assert digest != null; InputStream in = new BufferedInputStream(new FileInputStream(file)); boolean error = false; try { int bufSize = 1024; byte[] buffer = new byte[bufSize]; int n = in.read(buffer, 0, bufSize); int count = 0; while (n != -1) { count += n; digest.update(buffer, 0, n); n = in.read(buffer, 0, bufSize); } } catch (IOException e) { error = true; throw e; } finally { try { in.close(); } catch (IOException e) { if (!error) throw e; } } return digest.digest(); } /** * Get the hash of the supplied content, using the digest identified by the supplied name. Note that this method never closes * the supplied stream. * * @param digestName the name of the hashing function (or {@link MessageDigest message digest}) that should be used * @param stream the stream containing the content to be hashed; may not be null * @return the hash of the contents as a byte array * @throws NoSuchAlgorithmException if the supplied algorithm could not be found * @throws IOException if there is an error reading the stream */ public static byte[] getHash(String digestName, InputStream stream) throws NoSuchAlgorithmException, IOException { MessageDigest digest = MessageDigest.getInstance(digestName); assert digest != null; int bufSize = 1024; byte[] buffer = new byte[bufSize]; int n = stream.read(buffer, 0, bufSize); int count = 0; while (n != -1) { count += n; digest.update(buffer, 0, n); n = stream.read(buffer, 0, bufSize); } return digest.digest(); } }