Elgamal encryption

The Elgamal algorithm is an asymmetric key encryption algorithm for public key cryptography which is based on Diffie-Hellman key agreement. It was described by Taher Elgamal in 1984. The Elgamal algorithm is used in the free GNU Privacy Guard software, recent versions of PGP, and other cryptosystems. The Digital Signature Algorithm is a signature scheme is a variant of the ElGamal signature scheme, which should not be confused with the Elgamal algorithm.

References

• Taher Elgamal, "A Public-Key Cryptosystem and a Signature Scheme Based on Discrete Logarithms", IEEE Transactions on Information Theory, v. IT-31, n. 4, 1985, pp469–472 or CRYPTO 84, pp10–18, Springer-Verlag.
• Handbook of Applied Cryptography, contains a detailed description of Elgamal Algorithm in Chapter 8 (PDF file).