From ihughes@utexas.edu Mon Feb 28 15:38:26 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!utexas!ihughes
From: ihughes@utexas.edu (Ines Hughes)
Newsgroups: comp.sys.m68k
Subject: Discussion: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Feb28.153826.2603@utexas.edu>
Date: Mon, 28 Feb 1994 15:38:26 GMT
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Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.

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.

Did Marcus take the decryption EPROM with him when he left the lab?

-- 
Ines Hughes | ihughes@utexas.edu
PGP Key fingerprint: 47B1 9927 8EE6 FA00
"Keep the channels open."

From periksson@kth.se Tue Mar 01 01:16:26 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!kth!periksson
From: periksson@kth.se (Pavel Eriksson)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Mar01.011626.2985@kth.se>
Date: Tue, 01 Mar 1994 01:16:26 GMT
References: <1994Feb28.153826.2603@utexas.edu>
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In article <1994Feb28.153826.2603@utexas.edu>, ihughes@utexas.edu (Ines Hughes) 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.

-- 
Pavel Eriksson
Tape trading list upon request. SASE required for international mail.

From egirard@cern.ch Tue Mar 01 11:34:26 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!cern!egirard
From: egirard@cern.ch (Elaine Girard)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Mar01.113426.9976@cern.ch>
Date: Tue, 01 Mar 1994 11:34:26 GMT
References: <1994Feb28.153826.2603@utexas.edu>
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In article <1994Feb28.153826.2603@utexas.edu>, ihughes@utexas.edu (Ines Hughes) writes:
> Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.
> This indicates socket U14 held a cryptographic S-box lookup table for decrypting the Stardust keystream.

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

-- 
Elaine Girard | egirard@cern.ch
PGP Key fingerprint: F045 FB13 5958 3C4D
"Keep the channels open."

From sduarte@clari.net Wed Mar 02 14:29:26 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!clari!sduarte
From: sduarte@clari.net (Steve Duarte)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Mar02.142926.8216@clari.net>
Date: Wed, 02 Mar 1994 14:29:26 GMT
References: <1994Feb28.153826.2603@utexas.edu>
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In article <1994Feb28.153826.2603@utexas.edu>, ihughes@utexas.edu (Ines Hughes) writes:
> Further progress on reverse-engineering the empty socket U14 on the TWIN-68 Rev C coprocessor board.
> This indicates socket U14 held a cryptographic S-box lookup table for decrypting the Stardust keystream.

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

-- 
Steve Duarte -- ClariNet Communications Corp
"Extraordinary claims require extraordinary spectra."

From kfournier@uu.net Wed Mar 02 19:35:26 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!kfournier
From: kfournier@uu.net (Karen Fournier)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Disassembling socket U14 firmware on the TWIN-68 board
Message-ID: <1994Mar02.193526.8691@uu.net>
Date: Wed, 02 Mar 1994 19:35:26 GMT
References: <1994Feb28.153826.2603@utexas.edu> <1994Mar01.113426.9976@cern.ch>
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In article <1994Mar01.113426.9976@cern.ch>, egirard@cern.ch (Elaine Girard) writes:
> If we know the plain text of Nodes 01-10, we could potentially derive the S-box substitution table via known-plaintext attack!

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

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

-- 
Karen Fournier | kfournier@uu.net
PGP Key fingerprint: 61C5 21E3 F2D6 E9DF
"Keep the channels open."