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Unformatted text preview: loyed. In order to make money, Alice sells secrets. Anyone who is willing to pay the price can buy a secret. She even has a catalog. All her secrets are listed by number, with tantalizing titles: “Where is Jimmy Hoffa?”, “Who is secretly controlling the Trilateral Commission?”, “Why does Boris Yeltsin always look like he swallowed a live frog?”, and so on. Alice won’t give away two secrets for the price of one or even partial information about any of the secrets. Bob, a potential buyer, doesn’t want to pay for random secrets. He also doesn’t want to tell Alice which secrets he wants. It’s none of Alice’s business, and besides, Alice could then add “what secrets Bob is interested in” to her catalog. A poker protocol won’t work in this case, because at the end of the protocol Alice and Bob have to reveal their hands to each other. There are also tricks Bob can do to learn more than one secret. The solution is called all-or-nothing disclosure of secrets (ANDOS)  because, as soon as Bob has gained any information whatsoever about one of Alice’s secrets, he has wasted his chance to learn anything about any of the other secrets. There are several ANDOS protocols in the cryptographic literature. Some of them are discussed in Section 23.9. 4.14 Key Escrow
This excerpt is from Silvio Micali’s introduction to the topic : Currently, court-authorized line tapping is an effective method for securing criminals to justice. More importantly, in our opinion, it also prevents the further spread of crime by deterring the use of ordinary communication networks for unlawful purposes. Thus, there is a legitimate concern that widespread use of public-key cryptography may be a big boost for criminal and terrorist organizations. Indeed, many bills propose that a proper governmental agency, under circumstances allowed by law, should be able to obtain the clear text of any communication over a public network. At the present time, this requirement would translate into coercing citizens to either...
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- Fall '10