An asymmetric key encryption algorithm that uses a pair of different cryptographic keys to encrypt and decrypt. Created by cryptographer Dr. Taher Elgamal, the El Gamal algorithm is used in the free GNU Privacy Guard software, in recent versions of PGP, and in other cryptography systems for encryption and decryption and for digital signatures. Farlex, Inc. Internet Key Exchange. Farlex, Inc. Website. http:// encyclopedia.thefreedictionary.com/Internet%20key%20exchange.