Extracting a 3DES key from an IBM 4758

[R. A. Hettinga]

http://www.cl.cam.ac.uk/~rnc1/descrack/index.html



Extracting a 3DES key from an IBM 4758

Summary

The IBM 4758 is an extremely secure crytographic co-processor. It is used
by banking systems and in other security conscious applications to hold
keying material. It is designed to make it impossible to extract this
keying material unless you have the correct permissions and can involve
others in a conspiracy.

We are able, by a mixture of sleight-of-hand and raw processing power, to
persuade an IBM 4758 running IBM's ATM (cash machine) support software
called the "Common Cryptographic Architecture" (CCA) to export any and all
its DES and 3DES keys to us. All we need is:

*	about 20 minutes uninterrupted access to the device
*	one person's ability to use the Combine_Key_Parts permission
*	a standard off-the-shelf $995 FPGA evaluation board from Altera
*	about two days of "cracking" time


The attack can only be performed by an insider with physical access to the
cryptographic co-processor, but they can act alone. The FPGA evaluation
board is used as a "brute force key cracking" machine. Programming this is
a reasonably straightforward task that does not require specialist hardware
design knowledge. Since the board is pre-built and comes with all the
necessary connectors and tools, it is entirely suitable for amateur use.

Besides being the first documented attack on the IBM 4758 to be run "in
anger", we believe that this is only the second DES cracking machine in the
open community that has actually been built and then used to find an
unknown key!

Until IBM fix the CCA software to prevent our attack, banks are vulnerable
to a dishonest branch manager whose teenager has $995 and a few hours to
spend in duplicating our work.

Contents

What is an IBM 4758 ?
What is an FPGA ?
What are DES and 3DES ?
How the DES cracker works
Some relevant sums
How the attack works
Some real results
Who are we ?
Do It Yourself


Frequently Asked Questions

What does an IBM 4758 look like?
Who uses IBM 4758s?
Are all IBM 4758s susceptible to the attack?
What is the CCA?
Are the IBM 4758 and the CCA the same thing?
How hard is it to physically attack a IBM 4758?
I heard that the IBM 4758 is FIPS Level 4 validated. Have you broken the
validation?
So what does FIPS Level 4 validation mean?
Are other cryptoprocessors susceptible as well as the IBM 4758?
What is DES?
What is Triple-DES (3DES)?
How much stronger is Triple-DES than DES?
What privileges do you need to run this attack?
What information does this attack steal from the bank?
How do PIN numbers work?
Why is PIN number theft so dangerous?
How would a bank respond if someone did this attack?
Is all banking security this bad?
So can anyone who downloads this rip off a bank?
Who could rip off a bank then?
If this attack is so dangerous, why are you telling everyone?
Where can I go to book tickets to Bermuda?


Other links

Michael Bond. "Attacks on Cryptoprocessor Transaction Sets" Proceedings of
the CHES 2001 Workshop, Paris 2001. Springer Verlag LNCS 2162, pp 220-234.
Available on the web as:
http://www.cl.cam.ac.uk/~mkb23/research/Attacks-on-Crypto-TS.pdf

Michael Bond & Ross Anderson. "API-Level Attacks on Embedded Systems" IEEE
Computer 34(10), October 2001, pp 67-75.

"Brute force attacks on crytographic keys" a web-based survey of results,
plus an annotated bibliography concentrating on DES crackers.
http://www.cl.cam.ac.uk/~rnc1/brute.html

"IBM PCI Cryptographic Coprocessor CCA Basic Services Reference and Guide
for IBM 4758 Models 002 and 023 with Release 2.40", Seventh Edition,
September 2001. Available from:
ftp://www6.software.ibm.com/software/cryptocards/CCA_Basic_Services_Reference_240.pdf

------------------------------------------------------------------------
Return to Richard Clayton's Home Page
Return to Mike Bond's Home Page


last modified 29 OCT 2001 -- http://www.cl.cam.ac.uk/~rnc1/descrack/index.html

-- 
-----------------
R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'



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