1 /* 2 * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.crypto; 27 28 import java.security.*; 29 import java.security.spec.*; 30 31 /** 32 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) 33 * for the <code>KeyAgreement</code> class. 34 * All the abstract methods in this class must be implemented by each 35 * cryptographic service provider who wishes to supply the implementation 36 * of a particular key agreement algorithm. 37 * 38 * <p> The keys involved in establishing a shared secret are created by one 39 * of the 40 * key generators (<code>KeyPairGenerator</code> or 41 * <code>KeyGenerator</code>), a <code>KeyFactory</code>, or as a result from 42 * an intermediate phase of the key agreement protocol 43 * ({@link #engineDoPhase(java.security.Key, boolean) engineDoPhase}). 44 * 45 * <p> For each of the correspondents in the key exchange, 46 * <code>engineDoPhase</code> 47 * needs to be called. For example, if the key exchange is with one other 48 * party, <code>engineDoPhase</code> needs to be called once, with the 49 * <code>lastPhase</code> flag set to <code>true</code>. 50 * If the key exchange is 51 * with two other parties, <code>engineDoPhase</code> needs to be called twice, 52 * the first time setting the <code>lastPhase</code> flag to 53 * <code>false</code>, and the second time setting it to <code>true</code>. 54 * There may be any number of parties involved in a key exchange. 55 * 56 * @author Jan Luehe 57 * 58 * @see KeyGenerator 59 * @see SecretKey 60 * @since 1.4 61 */ 62 63 public abstract class KeyAgreementSpi { 64 65 /** 66 * Initializes this key agreement with the given key and source of 67 * randomness. The given key is required to contain all the algorithm 68 * parameters required for this key agreement. 69 * 70 * <p> If the key agreement algorithm requires random bytes, it gets them 71 * from the given source of randomness, <code>random</code>. 72 * However, if the underlying 73 * algorithm implementation does not require any random bytes, 74 * <code>random</code> is ignored. 75 * 76 * @param key the party's private information. For example, in the case 77 * of the Diffie-Hellman key agreement, this would be the party's own 78 * Diffie-Hellman private key. 79 * @param random the source of randomness 80 * 81 * @exception InvalidKeyException if the given key is 82 * inappropriate for this key agreement, e.g., is of the wrong type or 83 * has an incompatible algorithm type. 84 */ 85 protected abstract void engineInit(Key key, SecureRandom random) 86 throws InvalidKeyException; 87 88 /** 89 * Initializes this key agreement with the given key, set of 90 * algorithm parameters, and source of randomness. 91 * 92 * @param key the party's private information. For example, in the case 93 * of the Diffie-Hellman key agreement, this would be the party's own 94 * Diffie-Hellman private key. 95 * @param params the key agreement parameters 96 * @param random the source of randomness 97 * 98 * @exception InvalidKeyException if the given key is 99 * inappropriate for this key agreement, e.g., is of the wrong type or 100 * has an incompatible algorithm type. 101 * @exception InvalidAlgorithmParameterException if the given parameters 102 * are inappropriate for this key agreement. 103 */ 104 protected abstract void engineInit(Key key, AlgorithmParameterSpec params, 105 SecureRandom random) 106 throws InvalidKeyException, InvalidAlgorithmParameterException; 107 108 /** 109 * Executes the next phase of this key agreement with the given 110 * key that was received from one of the other parties involved in this key 111 * agreement. 112 * 113 * @param key the key for this phase. For example, in the case of 114 * Diffie-Hellman between 2 parties, this would be the other party's 115 * Diffie-Hellman public key. 116 * @param lastPhase flag which indicates whether or not this is the last 117 * phase of this key agreement. 118 * 119 * @return the (intermediate) key resulting from this phase, or null if 120 * this phase does not yield a key 121 * 122 * @exception InvalidKeyException if the given key is inappropriate for 123 * this phase. 124 * @exception IllegalStateException if this key agreement has not been 125 * initialized. 126 */ 127 protected abstract Key engineDoPhase(Key key, boolean lastPhase) 128 throws InvalidKeyException, IllegalStateException; 129 130 /** 131 * Generates the shared secret and returns it in a new buffer. 132 * 133 * <p>This method resets this <code>KeyAgreementSpi</code> object, 134 * so that it 135 * can be reused for further key agreements. Unless this key agreement is 136 * reinitialized with one of the <code>engineInit</code> methods, the same 137 * private information and algorithm parameters will be used for 138 * subsequent key agreements. 139 * 140 * @return the new buffer with the shared secret 141 * 142 * @exception IllegalStateException if this key agreement has not been 143 * completed yet 144 */ 145 protected abstract byte[] engineGenerateSecret() 146 throws IllegalStateException; 147 148 /** 149 * Generates the shared secret, and places it into the buffer 150 * <code>sharedSecret</code>, beginning at <code>offset</code> inclusive. 151 * 152 * <p>If the <code>sharedSecret</code> buffer is too small to hold the 153 * result, a <code>ShortBufferException</code> is thrown. 154 * In this case, this call should be repeated with a larger output buffer. 155 * 156 * <p>This method resets this <code>KeyAgreementSpi</code> object, 157 * so that it 158 * can be reused for further key agreements. Unless this key agreement is 159 * reinitialized with one of the <code>engineInit</code> methods, the same 160 * private information and algorithm parameters will be used for 161 * subsequent key agreements. 162 * 163 * @param sharedSecret the buffer for the shared secret 164 * @param offset the offset in <code>sharedSecret</code> where the 165 * shared secret will be stored 166 * 167 * @return the number of bytes placed into <code>sharedSecret</code> 168 * 169 * @exception IllegalStateException if this key agreement has not been 170 * completed yet 171 * @exception ShortBufferException if the given output buffer is too small 172 * to hold the secret 173 */ 174 protected abstract int engineGenerateSecret(byte[] sharedSecret, 175 int offset) 176 throws IllegalStateException, ShortBufferException; 177 178 /** 179 * Creates the shared secret and returns it as a secret key object 180 * of the requested algorithm type. 181 * 182 * <p>This method resets this <code>KeyAgreementSpi</code> object, 183 * so that it 184 * can be reused for further key agreements. Unless this key agreement is 185 * reinitialized with one of the <code>engineInit</code> methods, the same 186 * private information and algorithm parameters will be used for 187 * subsequent key agreements. 188 * 189 * @param algorithm the requested secret key algorithm 190 * 191 * @return the shared secret key 192 * 193 * @exception IllegalStateException if this key agreement has not been 194 * completed yet 195 * @exception NoSuchAlgorithmException if the requested secret key 196 * algorithm is not available 197 * @exception InvalidKeyException if the shared secret key material cannot 198 * be used to generate a secret key of the requested algorithm type (e.g., 199 * the key material is too short) 200 */ 201 protected abstract SecretKey engineGenerateSecret(String algorithm) 202 throws IllegalStateException, NoSuchAlgorithmException, 203 InvalidKeyException; 204 } 205
