Abstract

Introduction Our motivation is the notion of "timed-release crypto," where the goal is to encrypt a message so that it can not be decrypted by anyone, not even the sender, until a pre-determined amount of time has passed. The goal is to "send information into the future." This problem was first discussed by Timothy May [1]. What are the applications of "timed-release crypto"? Here are a few possibilities (some due to May): ffl A bidder in an auction wants to seal his bid so that it can only be opened after the bidding period is closed. ffl A homeowner wants to give his mortgage holder a series of encrypted mortgage payments. These might be encrypted digital cash with different decryption dates, so that one payment becomes decryptable (and thus usable by the bank) at the beginning of each successive month. ffl An individual wants to encrypt his diaries so that they are only decryptable after fifty years. ffl A key

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