ElGamal Encryption

	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 exchange. 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. The Digital Signature Algorithm (DSA) is a variant of the ElGamal signature scheme, which should not be confused with ElGamal encryption. ElGamal encryption can be defined over any cyclic group G, like multiplicative group of integers modulo ''n'' if and only if ''n'' is 1, 2, 4, ''p''''k'' or 2''p''''k'', where ''p'' is an odd prime and . Its security depends upon the difficulty of the Decisional Diffie Hellman Problem in G. The algorithm The algorithm can be described as first performing a Diffie–Hellman key exchange to establish a shared secret s, then using this as a one-time pad for encrypting the message. ElGamal encryption is performe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), adversarial behavior. More generally, cryptography is about constructing and analyzing Communication protocol, protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security (confidentiality, data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, Smart card#EMV, chip-based payment cards, digital currencies, password, computer passwords, and military communications. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ephemeral Key A cryptographic key is called ephemeral if it is generated for each execution of a key establishment process. In some cases ephemeral keys are used more than once, within a single session (e.g., in broadcast applications) where the sender generates only one ephemeral key pair per message and the private key is combined separately with each recipient's public key. Contrast with a static key. Private / public ephemeral key agreement key Private (resp. public) ephemeral key agreement keys are the private (resp. public) keys of asymmetric key pairs that are used a single key establishment transaction to establish one or more keys (e.g., key wrapping keys, data encryption keys, or MAC keys) and, optionally, other keying material (e.g., initialization vectors). See also * Cryptographic key types * Session key A session key is a single-use symmetric key used for encrypting all messages in one communication session. A closely related term is content encryption key (CEK), traffic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Chosen Ciphertext Attack A chosen-ciphertext attack (CCA) is an attack model for cryptanalysis Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ... where the cryptanalyst can gather information by obtaining the decryptions of chosen ciphertexts. From these pieces of information the adversary can attempt to recover the secret key used for decryption. For formal definitions of security against chosen-ciphertext attacks, see for example: Michael Luby and Mihir Bellare et al. Introduction A number of otherwise secure schemes can be defeated under chosen-ciphertext attack. For example, the El Gamal cryptosystem is semantic security, semantically secure under chosen-plaintext attack, but this semantic security can be trivially defeated under a chosen-ciphertext attack. Early versions of RSA (algorithm), RSA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]