Variable size block ciphers

Details Variable size block ciphers Variable size block ciphers

1995-07-06

1998-03-10

Tarcza, Thomas H.

Cryptography

Communication system using cryptography

Time segment interchange

H04L 918, H04L 900

Patent

active

057270627

ABSTRACT:
Data blocks of various size can be processed in fast, effective block cipher mechanisms. Variable size confusion layers and variable size diffusion layers combine to form variable size block ciphers. Block size can set (typically byte-by-byte) at design time or dynamically during operation.
The embodiment of FIG. 1 consists of horizontal layers alternating between confusion and diffusion. Here, each confusion layer, such as the layer including byte-wide substitution operation (16), uses keyed substitution tables which are initialized prior to operation. Simple and fast diffusion layers, such as the layer including byte-wide exclusive-OR (20), generally diffuse in just one direction. Consequently, multiple diffusion layers are usually required, such as those including byte-wide exclusive-OR operations (28) and (36). This kind of diffusion is unusual in a block cipher because it is extremely weak. However, because it can cover the entire block in a single layer, it is unexpectedly advantageous when combined with confusion layers.
The resulting variable size block ciphers are unusually fast and can be made arbitrarily strong. These ciphers can better fit existing applications, reduce overhead, and directly support large and efficient data blocks. Block size can be expanded dynamically, with good overall diffusion, without adding processing layers. These ciphers support better testing and analysis than previous designs, and also support unexpected new techniques for dynamic keying and authentication.

REFERENCES:
patent: 3798359 (1974-03-01), Feistel
patent: 3798360 (1974-03-01), Feistel
patent: 3962539 (1976-06-01), Ehrsam et al.
patent: 4078152 (1978-03-01), Tuckerman
patent: 4157454 (1979-06-01), Becker
patent: 4275265 (1981-06-01), Davida et al.
patent: 4316055 (1982-02-01), Feistel
patent: 4751733 (1988-06-01), Delayaye et al.
patent: 4979832 (1990-12-01), Ritter
patent: 5003597 (1991-03-01), Merkle
patent: 5214703 (1993-05-01), Massey et al.
patent: 5231662 (1993-07-01), van Rumpt et al.
Gutmann 1974 Excerpt from 400KB Secum File System Documentation.
Moyes, Rubin, Murray, Johnson, Scott, Schneier Messages from Sci. Crypt (Internet Messages from Jan. 1995).

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