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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java | |
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Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java')
-rw-r--r-- | libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java b/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java new file mode 100644 index 000000000..ad606f6c9 --- /dev/null +++ b/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalReceiver.java @@ -0,0 +1,99 @@ +/* ElGamalReceiver.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.javax.crypto.key.KeyAgreementException; +import gnu.javax.crypto.key.IncomingMessage; +import gnu.javax.crypto.key.OutgoingMessage; + +import java.math.BigInteger; +import java.security.SecureRandom; +import java.util.Map; + +import javax.crypto.interfaces.DHPrivateKey; + +/** + * This implementation is the receiver's part of the ElGamal key agreement + * exchange (B in [HAC]). + * + * @see ElGamalKeyAgreement + */ +public class ElGamalReceiver + extends ElGamalKeyAgreement +{ + /** The recipient's private key. */ + private DHPrivateKey B; + + // default 0-arguments constructor + + protected void engineInit(Map attributes) throws KeyAgreementException + { + rnd = (SecureRandom) attributes.get(SOURCE_OF_RANDOMNESS); + // One-time setup (key generation and publication). Each user B generates + // a keypair and publishes its public key + B = (DHPrivateKey) attributes.get(KA_ELGAMAL_RECIPIENT_PRIVATE_KEY); + if (B == null) + throw new KeyAgreementException("missing recipient private key"); + } + + protected OutgoingMessage engineProcessMessage(IncomingMessage in) + throws KeyAgreementException + { + switch (step) + { + case 0: + return computeSharedSecret(in); + default: + throw new IllegalStateException("unexpected state"); + } + } + + private OutgoingMessage computeSharedSecret(IncomingMessage in) + throws KeyAgreementException + { + // (b) B computes the same key on receipt of message (1) as + // K = (g^x)^xb mod p + BigInteger m1 = in.readMPI(); + if (m1 == null) + throw new KeyAgreementException("missing message (1)"); + ZZ = m1.modPow(B.getX(), B.getParams().getP()); // ZZ = (ya ^ xb) mod p + complete = true; + return null; + } +} |