초록 ▼

An information processing system including an encryption processing logic module and a decryption processing logic module for enabling the encryption of digital information to be decrypted with a decryption key K. The encryption processing module includes logic for encrypting the digital information

An information processing system including an encryption processing logic module and a decryption processing logic module for enabling the encryption of digital information to be decrypted with a decryption key K. The encryption processing module includes logic for encrypting the digital information, distributing the digital information and authorizing a user to decrypt the information. The decryption processing module includes logic for the user to communicate a user number n.sub.i to receive an authorization number a.sub.i from the authorization logic in the encryption processing module and extrication logic for extricating the decryption key. The user number n.sub.i uniquely identifies, and is valuable to, the user, so valuable in fact that the user would be unwilling to publically dislcose it. The extrication logic operates on a digital signet pair (a.sub.i, n.sub.i) consisting of the authorization number and user number, to extract K. The decryption logic then uses K to make the content available to the user. The extrication function is fully available to the user as a publicly-computable function in which it is computationally infeasible to use the extrication function to determine other valid digital signet pairs which can be used to extract K.

대표청구항 ▼

[ What is claimed is:] [1.] A method for operating a digital information processing system that distributes encryption information from an authorization processor to a plurality of user processors, the method comprising processor executed steps of:at the authorization processor:selecting a resilienc

[ What is claimed is:] [1.] A method for operating a digital information processing system that distributes encryption information from an authorization processor to a plurality of user processors, the method comprising processor executed steps of:at the authorization processor:selecting a resilience threshold t, and a number N;selecting a generator g of a multiplicative subgroup R of Z.sub.N.sup.*, wherein Z.sub.N.sup.* is a set of numbers less than and relatively prime to N and R consists of powers of g mod N;selecting random numbers k and b.sub.1, . . . , b.sub.t in the range [2:.vertline.R.vertline.], where .vertline.R.vertline. denotes the size of R and where the random numbers are relatively prime to .vertline.R.vertline.;generating g.sub.j =g.sup.b.sbsp.j mod N for 1.ltoreq.j.ltoreq.t;distributing to the user processors encrypted information with g.sub.j ; andreceiving a value n from a user processor, and returning to the user processor a signet a, wherein:EQU a=k-b.sub.1 n- . . . -b.sub.t n.sup.t mod .vertline.R.vertline.; reby the signet a is for enabling the user processor to generate a decryption key K to decrypt the encrypted information.