NewDES

NewDES, unlike DES, has no bit-level permutations, making it easy to implement in software. All operations are performed on whole bytes. It is a product cipher, consisting of 17 rounds performed on a 64-bit data block and makes use of a 120-bit key.

In each round, subkey material is XORed with the 1-byte sub-blocks of data, then fed through an S-box, the output of which is then XORed with another sub-block of data. In total, 8 XORs are performed in each round. The S-box is derived from the United States Declaration of Independence (used as a nothing-up-my-sleeve number).

Each set of two rounds uses seven 1-byte subkeys, which are derived by splitting 56 bits of the key into bytes. The key is then rotated 56 bits for use in the next two rounds.

Only a small amount of cryptanalysis has been published on NewDES. The designer showed that NewDES exhibits the full avalanche effect after seven rounds: every ciphertext bit depends on every plaintext bit and key bit.

NewDES has the same complementation property that DES has: namely, that if

:$E\_K(P)=C,$

then

:$E\_\{\backslash overline\{K\}\}(\backslash overline\{P\})=\backslash overline\{C\},$

where

:$\backslash overline\{x\}$

is the bitwise complement of x. This means that the work factor for a brute force attack is reduced by a factor of 2. Eli Biham also noticed that changing a full byte in all the key and data bytes leads to another complementation property. This reduces the work factor by 2⁸.

Biham's related-key attack can break NewDES with 2³³ chosen-key chosen plaintexts, meaning that NewDES is not as secure as DES.

John Kelsey, Bruce Schneier, and David Wagner used related-key cryptanalysis to develop another attack on NewDES; it requires 2³² known plaintexts and one related key.{{cite book |last1=Kelsey |first1=John |author-link1=John Kelsey (cryptanalyst) |last2=Schneier |first2=Bruce |author-link2=Bruce Schneier |last3=Wagner |first3=David |title=Information and Communications Security |chapter=Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X, NewDES, RC2, and TEA |series=Lecture Notes in Computer Science |author-link3=David A. Wagner |editor1-last=Han |editor1-first=Y. |editor2-last=Okamoto |editor2-first=T. |editor3-last=Qing |editor3-first=S. |date=1997 |volume=1334 |pages=233–246 |doi=10.1007/BFb0028479 |url=https://www.schneier.com/academic/archives/1997/11/related-key_cryptana.html |access-date=2018-10-10 |isbn=978-3-540-63696-0 |citeseerx=10.1.1.35.8112 }}

{{reflist}}

• {{cite journal |last1=Scott |first1=Robert |title=Wide Open Encryption Design Offers Flexible Implementations |journal=Cryptologia |date=January 1985 |volume=9 |issue=1 |pages=75–91 |doi=10.1080/0161-118591859799 }}
• {{cite book

| last = Schneier

| first = Bruce

| author-link = Bruce Schneier

| title = Applied Cryptography, Second Edition

| publisher = John Wiley & Sons

| year = 1996

| pages = 306–308

| isbn = 978-0-471-11709-4 }}

• {{cite newsgroup

| title = Revision of NEWDES

| last1 = Scott

| first1 = Robert

| date = 1996-03-02

| newsgroup = sci.crypt

| message-id = 4hafm9$r51@condor.ic.net

| url = https://groups.google.com/d/msg/sci.crypt/DFmZzBcgF2M/xZ36MbKGuX8J

| access-date = 2018-10-10

}}

• [https://web.archive.org/web/20080506105359/http://www.mirrors.wiretapped.net/security/cryptography/algorithms/newdes/ NewDES source code implementations]

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