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1: /* DSSPublicKey.java -- 2: Copyright 2001, 2002, 2003, 2006 Free Software Foundation, Inc. 3: 4: This file is a part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2 of the License, or (at 9: your option) any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; if not, write to the Free Software 18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19: USA 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.java.security.key.dss; 40: 41: import gnu.java.lang.CPStringBuilder; 42: 43: import gnu.java.security.Registry; 44: import gnu.java.security.action.GetPropertyAction; 45: import gnu.java.security.key.IKeyPairCodec; 46: 47: import java.math.BigInteger; 48: import java.security.AccessController; 49: import java.security.PublicKey; 50: import java.security.interfaces.DSAPublicKey; 51: 52: /** 53: * An object that embodies a DSS (Digital Signature Standard) public key. 54: * 55: * @see #getEncoded 56: */ 57: public class DSSPublicKey 58: extends DSSKey 59: implements PublicKey, DSAPublicKey 60: { 61: /** 62: * <code>y = g<sup>x</sup> mod p</code> where <code>x</code> is the 63: * private part of the DSA key. 64: */ 65: private final BigInteger y; 66: 67: /** String representation of this key. Cached for speed. */ 68: private transient String str; 69: 70: /** 71: * Conveience constructor. Calls the constructor with 5 arguments passing 72: * {@link Registry#RAW_ENCODING_ID} as the identifier of the preferred 73: * encoding format. 74: * 75: * @param p the public modulus. 76: * @param q the public prime divisor of <code>p-1</code>. 77: * @param g a generator of the unique cyclic group <code>Z<sup>*</sup> 78: * <sub>p</sub></code>. 79: * @param y the public key part. 80: */ 81: public DSSPublicKey(BigInteger p, BigInteger q, BigInteger g, BigInteger y) 82: { 83: this(Registry.RAW_ENCODING_ID, p, q, g, y); 84: } 85: 86: /** 87: * Constructs a new instance of <code>DSSPublicKey</code> given the 88: * designated arguments. 89: * 90: * @param preferredFormat the identifier of the preferred encoding format to 91: * use when externalizing this key. 92: * @param p the public modulus. 93: * @param q the public prime divisor of <code>p-1</code>. 94: * @param g a generator of the unique cyclic group <code>Z<sup>*</sup> 95: * <sub>p</sub></code>. 96: * @param y the public key part. 97: */ 98: public DSSPublicKey(int preferredFormat, BigInteger p, BigInteger q, 99: BigInteger g, BigInteger y) 100: { 101: super(preferredFormat == Registry.ASN1_ENCODING_ID ? Registry.X509_ENCODING_ID 102: : preferredFormat, 103: p, q, g); 104: this.y = y; 105: } 106: 107: /** 108: * A class method that takes the output of the <code>encodePublicKey()</code> 109: * method of a DSS keypair codec object (an instance implementing 110: * {@link gnu.java.security.key.IKeyPairCodec} for DSS keys, and re-constructs 111: * an instance of this object. 112: * 113: * @param k the contents of a previously encoded instance of this object. 114: * @exception ArrayIndexOutOfBoundsException if there is not enough bytes, in 115: * <code>k</code>, to represent a valid encoding of an 116: * instance of this object. 117: * @exception IllegalArgumentException if the byte sequence does not represent 118: * a valid encoding of an instance of this object. 119: */ 120: public static DSSPublicKey valueOf(byte[] k) 121: { 122: // try RAW codec 123: if (k[0] == Registry.MAGIC_RAW_DSS_PUBLIC_KEY[0]) 124: try 125: { 126: return (DSSPublicKey) new DSSKeyPairRawCodec().decodePublicKey(k); 127: } 128: catch (IllegalArgumentException ignored) 129: { 130: } 131: // try X.509 codec 132: return (DSSPublicKey) new DSSKeyPairX509Codec().decodePublicKey(k); 133: } 134: 135: public BigInteger getY() 136: { 137: return y; 138: } 139: 140: /** 141: * Returns the encoded form of this public key according to the designated 142: * format. 143: * 144: * @param format the desired format identifier of the resulting encoding. 145: * @return the byte sequence encoding this key according to the designated 146: * format. 147: * @exception IllegalArgumentException if the format is not supported. 148: * @see DSSKeyPairRawCodec 149: */ 150: public byte[] getEncoded(int format) 151: { 152: byte[] result; 153: switch (format) 154: { 155: case IKeyPairCodec.RAW_FORMAT: 156: result = new DSSKeyPairRawCodec().encodePublicKey(this); 157: break; 158: case IKeyPairCodec.X509_FORMAT: 159: result = new DSSKeyPairX509Codec().encodePublicKey(this); 160: break; 161: default: 162: throw new IllegalArgumentException("Unsupported encoding format: " 163: + format); 164: } 165: return result; 166: } 167: 168: /** 169: * Returns <code>true</code> if the designated object is an instance of 170: * {@link DSAPublicKey} and has the same DSS (Digital Signature Standard) 171: * parameter values as this one. 172: * 173: * @param obj the other non-null DSS key to compare to. 174: * @return <code>true</code> if the designated object is of the same type 175: * and value as this one. 176: */ 177: public boolean equals(Object obj) 178: { 179: if (obj == null) 180: return false; 181: 182: if (! (obj instanceof DSAPublicKey)) 183: return false; 184: 185: DSAPublicKey that = (DSAPublicKey) obj; 186: return super.equals(that) && y.equals(that.getY()); 187: } 188: 189: public String toString() 190: { 191: if (str == null) 192: { 193: String ls = (String) AccessController.doPrivileged 194: (new GetPropertyAction("line.separator")); 195: str = new CPStringBuilder(this.getClass().getName()).append("(") 196: .append(super.toString()).append(",").append(ls) 197: .append("y=0x").append(y.toString(16)).append(ls) 198: .append(")") 199: .toString(); 200: } 201: return str; 202: } 203: }