Master-Key Cryptosystems

We initiate the study of a new class of secret-key cryptosystems, called master-key cryptosystems, in which an authorized third party possesses a "master key" that allows efficient recovery of the cleartext without knowledge of the session key. One motivation for this study is that master-key cryptosystems could provide a less cumbersome alternative to key escrow in situations in which third-party access is required. We demonstrate that designing a master-key cryptosystem with acceptable performance is roughly equivalent to designing a public-key cryptosystem in which encryption is much faster than is possible with current public-key techniques. These results were presented at the Crypto rump session, Santa Barbara CA, August 1995. Master-Key Cryptosystems We initiate the study of a new class of secret-key cryptosystems, called master-key cryptosystems and abbreviated MKCSs, in which an authorized third party (hereinafter called "the government," although it need not literally be o..