A group of top cryptography experts gathered on Tuesday at the RSA conference in San Francisco to discuss future threats and how to counter them.

The group, which included BT Counterpane chief technical officer Bruce Schneier and Sun Microsystems chief security officer Whitfield Diffie, discussed the evolution of cryptography and the renewed importance placed on the subject by the emergence of cloud computing.

Diffie compared the security challenges of cloud computing to those posed by the rise of radio, a development that sparked much of the early work in cryptography.

Fellow panellist and Weizmann Institute of Science professor Adi Shamir suggested that the rise of cloud computing raised the prospect of new threats, such as the ability to remotely install illegal content on a user's system in hopes of framing a victim.

Schneier, however, was not as worried by the rise of cloud computing.

"I don't see a lot of difference," he argued. "Computing is all about trust, whether you trust the hardware or the software or the servers, we still have to trust our vendors."

The panellists also found themselves at odds over the prospects of a catastrophic digital attack. While Diffie spoke of a 'Digital 9/11', Schneier argued that analysis would be better directed at smaller, more likely scenarios.

"I get asked all the time about what is the worst that can happen, but the bigger risk is what's likely to happen, and it is not going to be the extreme catastrophic thing, it is going to be cybercrime," he said.

However, Schneier also cautioned against ignoring possible vulnerabilities simply because of a low chance of attack.

"Humans are very bad at intuitive math, they think one in a thousand or one in a million is perceived as hardly ever happens," he said. "A lot of these low probability events, we just assume that they will never happen."