From dcampbell@pacbell.net Fri Jun 23 14:03:12 1995
Path: ashpoly!cascade!brgate!saturno!pacbell!dcampbell
From: dcampbell@pacbell.net (Dave Campbell)
Newsgroups: comp.sys.m68k
Subject: [INFO] Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Jun23.140312.2239@pacbell.net>
Date: Fri, 23 Jun 1995 14:03:12 GMT
Organization: Pacific Bell Internet Services
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Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

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

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

-- 
Dave Campbell
Opinions expressed are solely my own and not those of Pacific Bell Internet Services.
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From jmoreno@u-tokyo.ac.jp Sat Jun 24 19:07:12 1995
Path: ashpoly!cascade!transat!ukc!fennimore!u-tokyo!jmoreno
From: jmoreno@u-tokyo.ac.jp (Julien Moreno)
Newsgroups: comp.sys.m68k
Subject: Re: [INFO] Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1995Jun24.190712.2985@u-tokyo.ac.jp>
Date: Sat, 24 Jun 1995 19:07:12 GMT
References: <1995Jun23.140312.2239@pacbell.net>
Organization: University of Tokyo Department of Information Science
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In article <1995Jun23.140312.2239@pacbell.net>, dcampbell@pacbell.net (Dave Campbell) writes:
> Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

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

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-- 
Julien Moreno -- University of Tokyo Department of Information Science
"5 sigma is a discovery. 7 is a question."