cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...

, SEAL (Software-Optimized Encryption Algorithm) is a

stream cipher 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 ...

optimised for machines with a 32-

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented a ...

word A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consen ...

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. The first version was published by

Phillip Rogaway Phillip Rogaway is a professor of computer science at the University of California, Davis. He graduated from Beverly Hills High School, and later earned a BA in computer science from UC Berkeley and completed his PhD in cryptography at MIT, in ...

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.

References

* "Software-efficient pseudorandom function and the use thereof for encryption" * "Computer readable device implementing a software-efficient pseudorandom function encryption" Stream ciphers {{crypto-stub