In cryptography, SEAL (Software-Optimized Encryption Algorithm) is a stream cipher optimised for machines with a 32-bit word size and plenty of RAM with a reported performance of around 4 cycles per byte. SEAL is actually a pseudorandom function family in that it can easily generate arbitrary portions of the keystream without having to start from the beginning. This makes it particularly well suited for applications like encrypting hard drives.
Cryptography or cryptology 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, electrical engineering, communication science, and physics. Applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications.
A stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the ciphertext stream. Since encryption of each digit is dependent on the current state of the cipher, it is also known as state cipher. In practice, a digit is typically a bit and the combining operation an exclusive-or (XOR).
The bit is a basic unit of information in information theory, computing, and digital communications. The name is a portmanteau of binary digit.
The first version was published by Phillip Rogaway and Don Coppersmith in 1994. The current version, published in 1997, is 3.0. SEAL, covered by two patents in the United States, both of which are assigned to IBM.
Phillip Rogaway is a professor of computer science at the University of California, Davis. He graduated with a BA in computer science from UC Berkeley and completed his PhD in cryptography at MIT, in the Theory of Computation group. He has taught at UC Davis since 1994. He was awarded the Paris Kanellakis Award in 2009 and the first Levchin Prize for Real World Cryptography in 2016. Rogaway received an NSF CAREER award in 1996, which the NSA had attempted to prevent by influencing the NSF.
Don Coppersmith is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-boxes, strengthening them against differential cryptanalysis. He is also the discoverer of the quantum Fourier transform. He has also worked on algorithms for computing discrete logarithms, the cryptanalysis of RSA, methods for rapid matrix multiplication and IBM's MARS cipher. Don is also a co-designer of the SEAL and Scream ciphers.
International Business Machines Corporation (IBM) is an American multinational information technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, founded in Endicott, New York, as the Computing-Tabulating-Recording Company (CTR) and was renamed "International Business Machines" in 1924.
