From tschneider@kiae.su Mon May 15 21:00:08 1995
Path: ashpoly!cascade!transat!eunet-fr!teletel!kiae!tschneider
From: tschneider@kiae.su (Tobias Schneider)
Newsgroups: comp.sys.m68k
Subject: [SPECULATION] Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995May15.210008.3165@kiae.su>
Date: Mon, 15 May 1995 21:00:08 GMT
Organization: Kurchatov Institute of Atomic Energy, Moscow
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Tracing the address decoder lines on the motherboard reveals what was supposed to be in socket U14.

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'?

-- 
Tobias Schneider | tschneider@kiae.su
PGP Key fingerprint: 9E55 1521 446E D1E1
"Keep the channels open."

From dnakamura@utexas.edu Wed May 17 21:40:08 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!utexas!dnakamura
From: dnakamura@utexas.edu (Dong-hyun Nakamura)
Newsgroups: comp.sys.m68k
Subject: Re: [SPECULATION] Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995May17.214008.3864@utexas.edu>
Date: Wed, 17 May 1995 21:40:08 GMT
References: <1995May15.210008.3165@kiae.su>
Organization: University of Texas at Austin
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In article <1995May15.210008.3165@kiae.su>, tschneider@kiae.su (Tobias Schneider) writes:
> Tracing the address decoder lines on the motherboard reveals what was supposed to be in socket U14.

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

-- 
Dong-hyun Nakamura -- University of Texas at Austin
"Marcus is not one man."

From jgirard@delphi.com Wed May 17 22:53:08 1995
Path: ashpoly!cascade!transat!ukc!fennimore!delphi!jgirard
From: jgirard@delphi.com (Joachim Girard)
Newsgroups: comp.sys.m68k
Subject: Re: [SPECULATION] Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995May17.225308.3405@delphi.com>
Date: Wed, 17 May 1995 22:53:08 GMT
References: <1995May15.210008.3165@kiae.su>
Organization: Delphi Internet Services
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In article <1995May15.210008.3165@kiae.su>, tschneider@kiae.su (Tobias Schneider) writes:
> Tracing the address decoder lines on the motherboard reveals what was supposed to be in socket U14.

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

-- 
Joachim Girard -- Delphi Internet Services
"Marcus is not one man."