Java tutorial
/* * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.crypto.spec; import java.security.MessageDigest; import java.security.spec.KeySpec; import java.util.Locale; import javax.crypto.SecretKey; /** * This class specifies a secret key in a provider-independent fashion. * * <p>It can be used to construct a <code>SecretKey</code> from a byte array, * without having to go through a (provider-based) * <code>SecretKeyFactory</code>. * * <p>This class is only useful for raw secret keys that can be represented as * a byte array and have no key parameters associated with them, e.g., DES or * Triple DES keys. * * @author Jan Luehe * * @see javax.crypto.SecretKey * @see javax.crypto.SecretKeyFactory * @since 1.4 */ public class SecretKeySpec implements KeySpec, SecretKey { private static final long serialVersionUID = 6577238317307289933L; /** * The secret key. * * @serial */ private byte[] key; /** * The name of the algorithm associated with this key. * * @serial */ private String algorithm; /** * Constructs a secret key from the given byte array. * * <p>This constructor does not check if the given bytes indeed specify a * secret key of the specified algorithm. For example, if the algorithm is * DES, this constructor does not check if <code>key</code> is 8 bytes * long, and also does not check for weak or semi-weak keys. * In order for those checks to be performed, an algorithm-specific * <i>key specification</i> class (in this case: * {@link DESKeySpec DESKeySpec}) * should be used. * * @param key the key material of the secret key. The contents of * the array are copied to protect against subsequent modification. * @param algorithm the name of the secret-key algorithm to be associated * with the given key material. * See the <a href="{@docRoot}/../specs/security/standard-names.html"> * Java Security Standard Algorithm Names</a> document * for information about standard algorithm names. * @exception IllegalArgumentException if <code>algorithm</code> * is null or <code>key</code> is null or empty. */ public SecretKeySpec(byte[] key, String algorithm) { if (key == null || algorithm == null) { throw new IllegalArgumentException("Missing argument"); } if (key.length == 0) { throw new IllegalArgumentException("Empty key"); } this.key = key.clone(); this.algorithm = algorithm; } /** * Constructs a secret key from the given byte array, using the first * <code>len</code> bytes of <code>key</code>, starting at * <code>offset</code> inclusive. * * <p> The bytes that constitute the secret key are * those between <code>key[offset]</code> and * <code>key[offset+len-1]</code> inclusive. * * <p>This constructor does not check if the given bytes indeed specify a * secret key of the specified algorithm. For example, if the algorithm is * DES, this constructor does not check if <code>key</code> is 8 bytes * long, and also does not check for weak or semi-weak keys. * In order for those checks to be performed, an algorithm-specific key * specification class (in this case: * {@link DESKeySpec DESKeySpec}) * must be used. * * @param key the key material of the secret key. The first * <code>len</code> bytes of the array beginning at * <code>offset</code> inclusive are copied to protect * against subsequent modification. * @param offset the offset in <code>key</code> where the key material * starts. * @param len the length of the key material. * @param algorithm the name of the secret-key algorithm to be associated * with the given key material. * See the <a href="{@docRoot}/../specs/security/standard-names.html"> * Java Security Standard Algorithm Names</a> document * for information about standard algorithm names. * @exception IllegalArgumentException if <code>algorithm</code> * is null or <code>key</code> is null, empty, or too short, * i.e. {@code key.length-offset<len}. * @exception ArrayIndexOutOfBoundsException is thrown if * <code>offset</code> or <code>len</code> index bytes outside the * <code>key</code>. */ public SecretKeySpec(byte[] key, int offset, int len, String algorithm) { if (key == null || algorithm == null) { throw new IllegalArgumentException("Missing argument"); } if (key.length == 0) { throw new IllegalArgumentException("Empty key"); } if (key.length - offset < len) { throw new IllegalArgumentException("Invalid offset/length combination"); } if (len < 0) { throw new ArrayIndexOutOfBoundsException("len is negative"); } this.key = new byte[len]; System.arraycopy(key, offset, this.key, 0, len); this.algorithm = algorithm; } /** * Returns the name of the algorithm associated with this secret key. * * @return the secret key algorithm. */ public String getAlgorithm() { return this.algorithm; } /** * Returns the name of the encoding format for this secret key. * * @return the string "RAW". */ public String getFormat() { return "RAW"; } /** * Returns the key material of this secret key. * * @return the key material. Returns a new array * each time this method is called. */ public byte[] getEncoded() { return this.key.clone(); } /** * Calculates a hash code value for the object. * Objects that are equal will also have the same hashcode. */ public int hashCode() { int retval = 0; for (int i = 1; i < this.key.length; i++) { retval += this.key[i] * i; } if (this.algorithm.equalsIgnoreCase("TripleDES")) return (retval ^= "desede".hashCode()); else return (retval ^= this.algorithm.toLowerCase(Locale.ENGLISH).hashCode()); } /** * Tests for equality between the specified object and this * object. Two SecretKeySpec objects are considered equal if * they are both SecretKey instances which have the * same case-insensitive algorithm name and key encoding. * * @param obj the object to test for equality with this object. * * @return true if the objects are considered equal, false if * <code>obj</code> is null or otherwise. */ public boolean equals(Object obj) { if (this == obj) return true; if (!(obj instanceof SecretKey)) return false; String thatAlg = ((SecretKey) obj).getAlgorithm(); if (!(thatAlg.equalsIgnoreCase(this.algorithm))) { if ((!(thatAlg.equalsIgnoreCase("DESede")) || !(this.algorithm.equalsIgnoreCase("TripleDES"))) && (!(thatAlg.equalsIgnoreCase("TripleDES")) || !(this.algorithm.equalsIgnoreCase("DESede")))) return false; } byte[] thatKey = ((SecretKey) obj).getEncoded(); return MessageDigest.isEqual(this.key, thatKey); } }