gnu.javax.crypto.key.dh
Class ElGamalKeyAgreement
- IKeyAgreementParty
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:
- A sends to B a single message allowing one-pass key agreement.
- A obtains an authentic copy of B's public key (p, g, yb), where yb =
g**xb.
- 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.
- B computes the same key K on receipt of the previous message as
(g**x)**xb.
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:
- Diffie-Hellman Key
Agreement Method
Eric Rescorla. - [HAC]: Handbook of
Applied Cryptography.
CRC Press, Inc. ISBN 0-8493-8523-7, 1997
Menezes, A., van Oorschot, P. and S. Vanstone.
engineInit, engineProcessMessage, engineReset, engineSharedSecret, getSharedSecret, init, isComplete, name, nextRandomBytes, processMessage, reset |
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
ElGamalKeyAgreement.java --
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