gnu.crypto.key.dh

Class ElGamalKeyAgreement

public abstract class ElGamalKeyAgreement extends BaseKeyAgreementParty

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:

RFC-2631 describes an Ephemeral-Static Mode of operations with Diffie-Hellman keypairs as follows:

 "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."
 

Reference:

  1. Diffie-Hellman Key Agreement Method
    Eric Rescorla.
  2. [HAC]: Handbook of Applied Cryptography.
    CRC Press, Inc. ISBN 0-8493-8523-7, 1997
    Menezes, A., van Oorschot, P. and S. Vanstone.

Version: $Revision: 1.2 $

Field Summary
static StringKA_ELGAMAL_RECIPIENT_PRIVATE_KEY
static StringKA_ELGAMAL_RECIPIENT_PUBLIC_KEY
static StringSOURCE_OF_RANDOMNESS
protected BigIntegerZZ
The shared secret key.
Constructor Summary
protected ElGamalKeyAgreement()
Method Summary
protected voidengineReset()
protected byte[]engineSharedSecret()

Field Detail

KA_ELGAMAL_RECIPIENT_PRIVATE_KEY

public static final String KA_ELGAMAL_RECIPIENT_PRIVATE_KEY

KA_ELGAMAL_RECIPIENT_PUBLIC_KEY

public static final String KA_ELGAMAL_RECIPIENT_PUBLIC_KEY

SOURCE_OF_RANDOMNESS

public static final String SOURCE_OF_RANDOMNESS

ZZ

protected BigInteger ZZ
The shared secret key.

Constructor Detail

ElGamalKeyAgreement

protected ElGamalKeyAgreement()

Method Detail

engineReset

protected void engineReset()

engineSharedSecret

protected byte[] engineSharedSecret()
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