Q:Information:  - In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryptiona series of well-defined steps that can be followed as a procedure. An alternative, less common term is "encipherment". To encipher or encode is to convert information into cipher or code. In common parlance, 'cipher' is synonymous with 'code', as they are both a set of steps that encrypt a message; however, the concepts are distinct in cryptography, especially classical cryptography.  - Manuel Blum (Caracas, 26 April 1938) is a Venezuelan computer scientist who received the Turing Award in 1995 "In recognition of his contributions to the foundations of computational complexity theory and its application to cryptography and program checking".<ref name="doi10.1145/321386.321395"></ref>  - A computer scientist is a scientist who has acquired the knowledge of computer science, the study of the theoretical foundations of information and computation and their application.  - Cryptanalysis (from the Greek "kryptós", "hidden", and "analýein", "to loosen" or "to untie") is the study of analyzing information systems in order to study the hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.  - The Weizmann Institute of Science ("Machon Weizmann LeMada") is a public research university in Rehovot, Israel, south of Tel Aviv established in 1934, 14 years before the State of Israel. It differs from other Israeli universities in that it offers only graduate and postgraduate degrees in the natural and exact sciences.  - Charles Weill Rackoff is an American cryptologist. Born and raised in New York City, he attended MIT as both an undergraduate and graduate student, and earned a Ph.D. degree in Computer Science in 1974. He spent a year as a postdoctoral scholar at INRIA in France.  - A chosen-ciphertext attack (CCA) is an attack model for cryptanalysis 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 hidden secret key used for decryption.  - In cryptography, plaintext, or cleartext, is un-encrypted information, as opposed to information encrypted for storage or transmission. "Plaintext" usually means un-encrypted information pending input into cryptographic algorithms, usually encryption algorithms. "Cleartext" usually refers to data that is transmitted or stored unencrypted ('in the clear').  - In cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can access it. Encryption does not of itself prevent interference, but denies the intelligible content to a would-be interceptor. In an encryption scheme, the intended information or message, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is in principle possible to decrypt the message without possessing the key, but, for a well-designed encryption scheme, large computational resources and skill are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users.  - The University of California, Berkeley, (also referred to as Berkeley, UC Berkeley, and Cal) is a public research university located in Berkeley, California. Founded in 1868, Berkeley is the oldest of the ten research universities affiliated with the University of California system, and is often cited as the top public university in the United States and around the world.  - In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext that is unreadable by a human or computer without the proper cipher to decrypt it. Decryption, the inverse of encryption, is the process of turning ciphertext into readable plaintext. Ciphertext is not to be confused with codetext because the latter is a result of a code, not a cipher.  - Moni Naor is an Israeli computer scientist, currently a professor at the Weizmann Institute of Science. Naor received his Ph.D. in 1989 at the University of California, Berkeley. His advisor was Manuel Blum.  - An adaptive chosen - ciphertext attack ( abbreviated as CCA2 ) is an interactive form of chosen - ciphertext attack in which an attacker sends a number of ciphertexts to be decrypted , then uses the results of these decryptions to select subsequent ciphertexts . It is to be distinguished from an indifferent chosen - ciphertext attack ( CCA1 ) . Charles Rackoff and Dan Simon defined CCA2 and suggested a system adapting the CCA1 definition and system of Moni Naor and Moti Yung . The goal of this attack is to gradually reveal information about an encrypted message , or about the decryption key itself . For public - key systems , adaptive - chosen - ciphertexts are generally applicable only when they have the property of ciphertext malleability -- that is , a ciphertext can be modified in specific ways that will have a predictable effect on the decryption of that message .  - In mathematics and computer science, an algorithm is a self-contained sequence of actions to be performed. Algorithms perform calculation, data processing, and/or automated reasoning tasks.  - Cryptography or cryptology (from Greek "kryptós", "hidden, secret"; and "graphein", "writing", or "-logia", "study", respectively) is the practice and study of techniques for secure communication in the presence of third parties called adversaries. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce.  - In cryptanalysis, attack models or attack types are a classification of cryptographic attacks specifying the kind of access a cryptanalyst has to a system under attack when attempting to "break" an encrypted message (also known as "ciphertext") generated by the system. The more elaborate the access the cryptanalyst can gain, the more useful information it can extracted and utilize for breaking the system.    Given the information above, choose from the list below the object entity that exhibits the relation 'instance of' with the subject 'adaptive chosen-ciphertext attack'.  Choices: - algorithm  - application  - april  - attack model  - award  - cipher  - city  - classification  - communication  - computer  - cryptography  - degree  - encoding  - engineering  - information  - institute  - interceptor  - mathematics  - message  - name  - process  - public  - reasoning  - research  - result  - science  - security  - sequence  - series  - set  - state  - student  - study  - system  - ten  - university  - writing  - year
A:
attack model