I've been thinking about a certain kind of distributed application involving cryptography, and I wondered if anything like this exists, and if not, at least any accepted cryptographic method for doing this: Suppose a scenario in which an individal has knowledge or substantial suspicion that another person, group, or state are interested in letting him have an accident or otherwise making him disappear. Now, that individual could have generally important information, evidence about exactly that plot, or other evidence or black-mail material against those people who potentially harbor these intentions against him. In this scenario, the kind of application I'm thinking of would allow that individual to record all of his important information, encrypt it, and post multiple copies to a decentralized network of cyberspace sites, ideally anonymously (perhaps like freenet, with the big problem that freenet and similar solutions provide no guarantee for that information to remain there indefinitely). Now the key part which is somewhat harder: it should only be possible to decrypt that information for any third party in the case anything really happens to that individual (prison, death, disappearance, ...). There must be a system in which the individual must regularly visit sites on a decentralized network and perform some (pseudonymous) action of self-authentication that proves he's still there, and that therefore the decryption key should not yet be released. I presume that the most viable route to do this would be via decentralized escrow of the encryption key for the information, i.e. you split the key in three parts and provide multiple copies of each key to different decentralized nodes or parties, while you need to make sure that no party ever gets all three parts of the key. Only if you don't perform a regular authentication (because you disappeared), any three parties who together have your key will receive information about each other, reassemble the key, fetch your decentrally stored ciphertext and decrypt it, then posting it on the web or sending it to the media or friends, or whatever. I admit this system is a little complicated, but I think it would be the only viable method of making sure information in this scenario is kept intact, and at the same time only available when that individual owning the information stops regularly affirming that he is still alive. This may sound a bit paranoid at first, but it is a real important application for which many people could have a real interest, which could even help individuals provide some incentive for criminal/ intelligence/whatever groups to leave them alone, a "Passive Blackmail", if you want. Taking a look at recent history, the disappearing or otherwise strange death of hackers and other geeks and politically active figures isn't a very rare occurrence... So thanks in advance for any information you might have about this. -- --------------------------- Mixter Development/Consulting 2xs LTD. - http://2xss.com Tel: +972-9-9519980 Fax: +972-9-9519982 Mail: mixter@2xss.com