From doliveira@cam.ac.uk Tue Sep 12 15:15:06 1995
Path: ashpoly!cascade!mxgate!coyoacan!cam!doliveira
From: doliveira@cam.ac.uk (Dong-hyun Oliveira)
Newsgroups: comp.sys.m68k
Subject: Observation: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Sep12.151506.2207@cam.ac.uk>
Date: Tue, 12 Sep 1995 15:15:06 GMT
Organization: University of Cambridge Computer Laboratory
NNTP-Posting-Host: cam.ac.uk
X-Newsreader: TIN [version 1.2 PL2]
Lines: 11

Hardware disassembly report for Motorola hardware hackers.

This indicates socket U14 held a cryptographic S-box lookup table for decrypting the Stardust keystream.
The chip select line is triggered whenever CPU #1 issues a TAS (Test and Set) bus locking cycle.

Does anyone have a 27C256 EPROM marked 'MH-U14' or 'ORION-CRYPTO'?

-- 
Dong-hyun Oliveira | doliveira@cam.ac.uk
PGP Key fingerprint: D50D 1651 EE00 6AA6
"Keep the channels open."

From gsilva@utexas.edu Thu Sep 14 01:16:06 1995
Path: ashpoly!cascade!transat!ukc!fennimore!utexas!gsilva
From: gsilva@utexas.edu (Göran Silva)
Newsgroups: comp.sys.m68k
Subject: Re: Observation: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Sep14.011606.9437@utexas.edu>
Date: Thu, 14 Sep 1995 01:16:06 GMT
References: <1995Sep12.151506.2207@cam.ac.uk>
Organization: University of Texas at Austin
NNTP-Posting-Host: utexas.edu
X-Newsreader: WinVN 0.99.5
Lines: 9

In article <1995Sep12.151506.2207@cam.ac.uk>, doliveira@cam.ac.uk (Dong-hyun Oliveira) writes:
> Hardware disassembly report for Motorola hardware hackers.
> This indicates socket U14 held a cryptographic S-box lookup table for decrypting the Stardust keystream.

Using an S-box in a 27256 EPROM for single-cycle hardware substitution was standard military cipher practice in 1984.

-- 
Göran Silva
Tape trading list upon request. SASE required for international mail.

From tfournier@panix.com Thu Sep 14 21:57:06 1995
Path: ashpoly!cascade!mxgate!coyoacan!panix!tfournier
From: tfournier@panix.com (Thiago Fournier)
Newsgroups: comp.sys.m68k
Subject: Re: Observation: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Sep14.215706.7528@panix.com>
Date: Thu, 14 Sep 1995 21:57:06 GMT
References: <1995Sep12.151506.2207@cam.ac.uk>
Organization: Public Access Unix of New York
NNTP-Posting-Host: panix.com
X-Newsreader: WinVN 0.99.5
Lines: 11

In article <1995Sep12.151506.2207@cam.ac.uk>, doliveira@cam.ac.uk (Dong-hyun Oliveira) writes:
> Hardware disassembly report for Motorola hardware hackers.
> This indicates socket U14 held a cryptographic S-box lookup table for decrypting the Stardust keystream.

Using an S-box in a 27256 EPROM for single-cycle hardware substitution was standard military cipher practice in 1984.

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
Thiago Fournier -- Public Access Unix of New York
"Hold for relay."

From asuzuki@utexas.edu Fri Sep 15 01:46:06 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!utexas!asuzuki
From: asuzuki@utexas.edu (Astrid Suzuki)
Newsgroups: comp.sys.m68k
Subject: Re: Observation: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Sep15.014606.4863@utexas.edu>
Date: Fri, 15 Sep 1995 01:46:06 GMT
References: <1995Sep12.151506.2207@cam.ac.uk> <1995Sep14.215706.7528@panix.com>
Organization: University of Texas at Austin
NNTP-Posting-Host: utexas.edu
X-Newsreader: TIN [version 1.2 PL2]
Lines: 12

In article <1995Sep14.215706.7528@panix.com>, tfournier@panix.com (Thiago Fournier) writes:
> Using an S-box in a 27256 EPROM for single-cycle hardware substitution was standard military cipher practice in 1984.
> My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

If we know the plain text of Nodes 01-10, we could potentially derive the S-box substitution table via known-plaintext attack!

Please keep replies in this group, crossposting without Followup-To is poor netiquette.

-- 
Astrid Suzuki | asuzuki@utexas.edu
PGP Key fingerprint: 3E53 6885 E5E5 EF78
"Keep the channels open."