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The ElGamal cryptosystem is usually used in a hybrid cryptosystem.
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ElGamal and cryptosystem
The ElGamal cryptosystem, invented by Taher ElGamal.
I. e., the message itself is encrypted using a symmetric cryptosystem and ElGamal is then used
In the ElGamal cryptosystem, a plaintext is encrypted as, where is the public key.
Cunningham chains are now considered useful in cryptographic systems since " they provide two concurrent suitable settings for the ElGamal cryptosystem ... can be implemented in any field where the discrete logarithm problem is difficult.
In 1985, Elgamal published a paper titled A Public key Cryptosystem and A Signature Scheme based on discrete Logarithms in which he proposed the design of the ElGamal discrete log cryptosystem and of the ElGamal signature scheme.
* LUC is a public-key cryptosystem based on Lucas sequences that implements the analogs of ElGamal ( LUCELG ), Diffie-Hellman ( LUCDIF ), and RSA ( LUCRSA ).
ElGamal and is
In cryptography, the ElGamal encryption system is an asymmetric key encryption algorithm for public-key cryptography which is based on the Diffie – Hellman key exchange.
ElGamal encryption is used in the free GNU Privacy Guard software, recent versions of PGP, and other cryptosystems.
The Digital Signature Algorithm is a variant of the ElGamal signature scheme, which should not be confused with ElGamal encryption.
ElGamal encryption is unconditionally malleable, and therefore is not secure under chosen ciphertext attack.
ElGamal encryption is probabilistic, meaning that a single plaintext can be encrypted to many possible ciphertexts, with the consequence that a general ElGamal encryption produces a 2: 1 expansion in size from plaintext to ciphertext.
DSA is a variant of the ElGamal Signature Scheme.
DSA is similar to the ElGamal signature scheme.
In contrast, the Cramer-Shoup system ( which is based on ElGamal ) is not malleable.
In the Paillier, ElGamal, and RSA cryptosystems, it is also possible to combine several ciphertexts together in a useful way to produce a related ciphertext.
Elgamal is sometimes written as El Gamal or ElGamal, but Elgamal is now preferred.
It is an ElGamal variant, similar to the Digital Signature Algorithm and GOST R 34. 10-94.
It is used as the basis to prove the security of many cryptographic protocols, most notably the ElGamal and Cramer – Shoup cryptosystems.
ElGamal and used
The security of the ElGamal scheme depends on the properties of the underlying group as well as any padding scheme used on the messages.
The ElGamal signature algorithm described in this article is rarely used in practice.
ElGamal and .
PGP 3 introduced use of the CAST-128 ( a. k. a. CAST5 ) symmetric key algorithm, and the DSA and ElGamal asymmetric key algorithms, all of which were unencumbered by patents.
Some special and specific algorithms have been developed to aid in attacking some public key encryption algorithms-both RSA and ElGamal encryption have known attacks that are much faster than the brute-force approach.
ElGamal encryption can be defined over any cyclic group.
ElGamal encryption consists of three components: the key generator, the encryption algorithm, and the decryption algorithm.
ElGamal achieves semantic security.
Other schemes related to ElGamal which achieve security against chosen ciphertext attacks have also been proposed.
Encryption under ElGamal requires two exponentiations ; however, these exponentiations are independent of the message and can be computed ahead of time if need be.
cryptosystem and is
The goal in finding these " hard " instances is for their use in public key cryptography systems, such as the Merkle-Hellman knapsack cryptosystem.
Key escrow ( also known as a “ fair ” cryptosystem ) is an arrangement in which the keys needed to decrypt encrypted data are held in escrow so that, under certain circumstances, an authorized third party may gain access to those keys.
In 1979, Michael O. Rabin published a related cryptosystem that is provably secure, at least as long as the factorization of the public key remains difficult-it remains an assumption that RSA also enjoys this security.
Most are used in hybrid cryptosystems for reasons of efficiency-in such a cryptosystem, a shared secret key (" session key ") is generated by one party, and this much briefer session key is then encrypted by each recipient's public key.
An example is PGP released as source code, and generally regarded ( when properly used ) as a military-grade cryptosystem.
In cryptography, Kerckhoffs's principle ( also called Kerckhoffs's Desiderata, Kerckhoffs's assumption, axiom, or law ) was stated by Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.
A backdoor in a computer system ( or cryptosystem or algorithm ) is a method of bypassing normal authentication, securing remote access to a computer, obtaining access to plaintext, and so on, while attempting to remain undetected.
The Cramer – Shoup cryptosystem is secure under chosen ciphertext attack assuming DDH holds for.
Merkle-Hellman is an asymmetric-key cryptosystem, meaning that for communication, two keys are required: a public key and a private key.
Malleability is often an undesirable property in a general-purpose cryptosystem, since it allows an attacker to modify the contents of a message.
In the RSA cryptosystem, a plaintext is encrypted as, where is the public key.
For example, the El Gamal cryptosystem is semantically secure under chosen-plaintext attack, but this semantic security can be trivially defeated under a chosen-ciphertext attack.
When a cryptosystem is vulnerable to chosen-ciphertext attack, implementers must be careful to avoid situations in which an adversary might be able to decrypt chosen-ciphertexts ( i. e., avoid providing a decryption oracle ).
A better approach is to use a cryptosystem which is provably secure under chosen-ciphertext attack, including ( among others ) RSA-OAEP, Cramer-Shoup and many forms of authenticated symmetric encryption.
Ciphertext is generally the easiest part of a cryptosystem to obtain and therefore is an important part of cryptanalysis.
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