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Extracting a 3DES key from an IBM 4758

------- Forwarded message follows ------- Date sent: Thu, 8 Nov 2001 23:12:09 -0500 To: Digital Bearer Settlement List <dbs@philodox.com>, dcsb@ai.mit.edu, e$@vmeng.com, cryptography@wasabisystems.com From: "R. A. Hettinga" <rah@shipwright.com> Subject: Extracting a 3DES key from an IBM 4758

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

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?