Front cover - IBM Redbooks

28 Lotus Security Handbook
cipher that does not require much memory. Yet, the structure of the cipher is
very complex and hence difficult to analyze.
► IDEA (International Data Encryption Algorithm, by Xuejia Lai and James
Massey) - Originally this was called PES - Proposed Encryption Standard. It
was later improved and named IPES and then named IDEA, or International
Data Encryption Algorithm; its claim to fame is that it is part of PGP. It is a
64-bit iterative block cipher with a 128-bit key. The encryption process
requires eight complex rounds, but the speed of IDEA in software is similar to
that of DES.
► CAST (Canadian Algorithm by Carlisle Adams and Stafford Tavares) - This is
a popular 64-bit cipher that allows key sizes up to 128 bits. The name CAST
stands for Carlisle Adams and Stafford Tavares, the original inventors of
CAST. CAST-128 is owned by Entrust Technologies but is free for
commercial as well as non-commercial use. CAST-256 is a freely available
extension of CAST-128 that accepts up to 256 bits of key size and that has a
128-bit block size. CAST-256 was one of the original candidates for the AES.
Common stream ciphers
► RC4 (variable-key-size encryption algorithm created by Ron Rivest of RSA
Security) - RC4 is used for secure communications, as in the encryption of
traffic to and from secure web sites using the SSL protocol. RC4 is a cipher
with a key size of up to 2048 bits (256 bytes).
► SEAL (Software Efficient ALgorithm, by Phil Rogaway and Don Coppersmith
of IBM in 1993) - This algorithm is covered by US Patent 5,454,039. The
cipher is based on 32-bit words, encrypts at about 4 cycles per byte, and uses
a 160 bit key for encryption. It is considered very safe.
► WAKE (World Auto Key Encryption algorithm by David J Wheeler). This is an
encryption system for medium speed encryption of blocks and it offers high
security. It is intended to be fast on most computers and relies on repeated
table use and having a large state space.
Note: An interesting bit of trivia is that RC1 never went further than Rivest's
notebook and RC3 was broken at RSADSI during development.
Advantages of symmetric key algorithms
As we have shown, there are a number of symmetric key ciphers in use. In
addition to those already mentioned, we describe those used in Notes, Domino
and other Lotus collaboration products later in this document. For now, let’s talk
about the advantages that all these Symmetric Key Algorithms share in common.
They are fast and need relatively little system overhead because of the short
keys which provide relatively high security. For this reason, symmetric key