SEAL (cipher)

SEAL (Software -Optimized Encryption Algorithm ) is a technology developed by Phillip Rogaway and Don Coppersmith at IBM stream cipher with a key length of 160 bits, which can be very efficiently implemented in software. SEAL is considered as a very fast encryption algorithm, which, however, requires relatively much space. This efficiency is bought by that before any encryption takes place, a 9 * 32 bit S-box is calculated. This is done with SHA.

SEAL is not a classical stream cipher, but a pseudo-random function. The current message key does not depend on a state by the two opposite sides have in common, but only on the key and the message number. In this way, you do not resynchronize when a message is lost on the channel.

Is the S-box is initialized, so SEAL needs to encrypt a plaintext bytes about 5 elementary CPU operations, which makes it one of the fastest software algorithms

1997 people realized that the key stream of SEAL after about 234 bytes deviates from the randomness. Then SEAL was slightly modified and called SEAL 3.0. A little later, an attack on SEAL 3.0 is described by 244 bytes.

• Stream encryption