RSA Finds More Security Flaws in RFID - ' Page Two '

One of TI's customers, Exxon Mobil Corp., uses the DST-40 tag in its Speedpass electronic payment system.

"We've been over all of this with Exxon, and they don't see any more risk [now] beyond the risk they were at already," Sabetti said.

Ari Juels, RSA's principal research scientist, agreed that customers have a right to try to "strike a balance" between speed, cost, and security.

"But what we're saying is that if you're going to bother to build in encryption at all, you should do it correctly. You shouldn't use a proprietary encryption algorithm," Juels said.

Other companies also make RFID tags for the same general markets. Why did the researchers focus only on TI? "Because TI is the most visible." Juels said.

But TI wasn't being "picked on," he said. "We're also intending to look at a range of [other] RFID systems, [including both] active and passive RFID tags. Various [RFID systems] have various security and privacy weaknesses."

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For his part, Sabetti took issue with some of the cryptographic researchers' methods and findings.

The DST simulation system used in the attacks "took up the entire back seat of a car," he said. "[The researchers] were unable to produce an emulator which would be considered small or efficient."

Sabetti also said that the RSA and Johns Hopkins researchers had demonstrated the attack for him, and that during the demo, they hadn't been able to intercept information outside of a two-foot range.

"[Two feet] is a bit naïve," Juels said. "That is the nominal read range. Other systems, [with] a gate antenna, might achieve several feet for active scanning. Also, if an attacker waits until someone is [actually] using a Speedpass token, the potential passive eavesdropping range could be 10 feet."

But Juels admitted that the researchers used only "crude" equipment in the attack against TI's 40-bit encryption.

"Our attempt to do this was rather crude and uninformed, [and] cobbled together with some fairly inexpensive equipment. [But] once these systems have been widely deployed, there will be better equipment available. This was only a proof-of-concept [attack]," he said.