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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalKeyAgreement.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalKeyAgreement.java | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalKeyAgreement.java b/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalKeyAgreement.java new file mode 100644 index 000000000..967eda3f5 --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalKeyAgreement.java @@ -0,0 +1,115 @@ +/* ElGamalKeyAgreement.java -- + Copyright (C) 2003, 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at +your option) any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.javax.crypto.key.dh; + +import gnu.java.security.Registry; +import gnu.java.security.util.Util; + +import gnu.javax.crypto.key.BaseKeyAgreementParty; +import gnu.javax.crypto.key.KeyAgreementException; + +import java.math.BigInteger; + +/** + * The ElGamal key agreement, also known as the half-certified Diffie-Hellman + * key agreement, is described in the Handbook of Applied Cryptography [HAC] as + * follows: + * <ul> + * <li>A sends to B a single message allowing one-pass key agreement.</li> + * <li>A obtains an authentic copy of B's public key (p, g, yb), where yb = + * g**xb.</li> + * <li>A chooses a random integer x, 1 <= x <= p-2, and sends B the + * message g**x. A computes the shared secret key K as yb**x.</li> + * <li>B computes the same key K on receipt of the previous message as + * (g**x)**xb.</li> + * </ul> + * <p> + * RFC-2631 describes an <i>Ephemeral-Static Mode</i> of operations with + * Diffie-Hellman keypairs as follows: + * <pre> + * "In Ephemeral-Static mode, the recipient has a static (and certified) + * key pair, but the sender generates a new key pair for each message + * and sends it using the originatorKey production. If the sender's key + * is freshly generated for each message, the shared secret ZZ will be + * similarly different for each message and partyAInfo MAY be omitted, + * since it serves merely to decouple multiple KEKs generated by the + * same set of pairwise keys. If, however, the same ephemeral sender key + * is used for multiple messages (e.g. it is cached as a performance + * optimization) then a separate partyAInfo MUST be used for each + * message. All implementations of this standard MUST implement + * Ephemeral-Static mode." + * </pre> + * <p> + * Reference: + * <ol> + * <li><a href="http://www.ietf.org/rfc/rfc2631.txt">Diffie-Hellman Key + * Agreement Method</a><br> + * Eric Rescorla.</li> + * <li><a href="http://www.cacr.math.uwaterloo.ca/hac">[HAC]</a>: Handbook of + * Applied Cryptography.<br> + * CRC Press, Inc. ISBN 0-8493-8523-7, 1997<br> + * Menezes, A., van Oorschot, P. and S. Vanstone.</li> + * </ol> + */ +public abstract class ElGamalKeyAgreement + extends BaseKeyAgreementParty +{ + public static final String SOURCE_OF_RANDOMNESS = "gnu.crypto.elgamal.ka.prng"; + public static final String KA_ELGAMAL_RECIPIENT_PRIVATE_KEY = + "gnu.crypto.elgamal.ka.recipient.private.key"; + public static final String KA_ELGAMAL_RECIPIENT_PUBLIC_KEY = + "gnu.crypto.elgamal.ka.recipient.public.key"; + /** The shared secret key. */ + protected BigInteger ZZ; + + protected ElGamalKeyAgreement() + { + super(Registry.ELGAMAL_KA); + } + + protected byte[] engineSharedSecret() throws KeyAgreementException + { + return Util.trim(ZZ); + } + + protected void engineReset() + { + ZZ = null; + } +} |