Dutch Fiasco Demonstrates Futility Of Security Through Obscurity
Date : 01 23 2008 Category : Business
Techdirt
Recent research on the security vulnerabilities of a new Dutch fare card system offers important lessons for computer security. The Dutch government spent $2 billion on the system, which has now been demonstrated to have fatal flaws. The researchers disassembled the smart cards used by the system and took high-resolution photographs of the circuitry. This allowed them to reverse-engineer the encryption algorithms being used by the system. As Felten points out, this wouldn't have been a problem if the Dutch had used an open crypto algorithm that has been widely tested and found to be secure. But because the system relied on algorithmic secrecy for security, this could be catastrophic. The algorithm uses a relatively short 48-bit key. This means that once the algorithm is known, it becomes possible to perform a brute-force attack, simply trying all 281 trillion possible keys in parallel until the correct one is found. That requires a non-trivial amount of computing power, but it's well within the capabilities of modern computer hardware. Indeed, this is precisely the approach taken by a Johns Hopkins research group three years ago when they cracked the encryption on the Exxon Mobil Speedpass, which used a 40-bit key. Brute forcing the 40-bit algorithm reportedly took the Hopkins team about 20 minutes, which suggests that -- even ignoring improvements in hardware -- it should be possible to brute force a 48-bit key in under a week. Since they're just deploying the system now and are presumably planning to use it for a decade or more, 48 bits is woefully inadequate. They ought to have used a standard, widely-tested cryptographic algorithm with a significantly longer key size, in order to make brute force attacks impractical.
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