User guide

Appendix A. Encryption Standards
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of the decisional Diffie–Hellman assumption. Developed by Ronald Cramer and Victor Shoup in 1998,
it is an extension of the Elgamal cryptosystem. In contrast to Elgamal, which is extremely malleable,
Cramer–Shoup adds additional elements to ensure non-malleability even against a resourceful
attacker. This non-malleability is achieved through the use of a collision-resistant hash function and
additional computations, resulting in a ciphertext which is twice as large as in Elgamal.
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A.2.6. ElGamal Encryption
In cryptography, the ElGamal encryption system is an asymmetric key encryption algorithm for public-
key cryptography which is based on the Diffie-Hellman key agreement. It was described by Taher
Elgamal in 1985. ElGamal encryption is used in the free GNU Privacy Guard software, recent versions
of PGP, and other cryptosystems.
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"Cramer-Shoup cryptosystem." Wikipedia. 24 February 2010 http://en.wikipedia.org/wiki/Cramer–Shoup_cryptosystem
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"ElGamal encryption" Wikipedia. 24 February 2010 http://en.wikipedia.org/wiki/ElGamal_encryption