Time-capsule crypto to help journalists protect theirsources

Jonathan Zittrain writes, "I published an op-ed in the Boston Globe today musing on the prospects for 'time capsule encryption,' one of several ways of storing information that renders it inaccessible to anyone until certain conditions -- such as the passage of time -- are met. I could see libraries and archives offering such technology as part of accepting papers and manuscripts, especially in the wake of the "Belfast Project" situation, where a library promised confidentiality for accounts of the Troubles in North Ireland, and then found itself amidst subpoenas from law enforcement looking to solve long-cold cases. But the principle could apply to any person or company thinking that there's a choice between leaving information exposed to leakage, or destroying it entirely."

I'm less enthusiastic about this than Jonathan is. I think calibrating the strength of your time-capsule is very hard. If the NSA might be an order of magnitude faster than the rest of us at brute-force cryptanalysis, that means you need to make your 10-year capsule strong enough to last for 100 years just to be on the safe side. Same goes for proof-of-work. Read the rest