Function type cryptographic system, key generation device, the encryption device, decoding device, function type encryption method, and program

摘要

PROBLEM TO BE SOLVED: To provide a functional encryption system which can process various language expressions including negative expressions and also enhance a processing speed of decryption.;SOLUTION: A functional encryption system defines: an n^→ as a d-dimensional attribute format; x^→ and v^→ as an n_t-dimensional attribute vector; Γ as an attribute set of {(t, v^→_t)}(t=1, ..., d); a ρ(-) as a label of a combination of positive forms (t, x^→.) or a combination of negative forms ￢(t, x^→.) for -; and an S as access structure composed of a matrix M and a label ρ. A key generation device 1 generates a public key pk and a master secret key sk on the basis of input of the attribute format n^→. The key generation device 1 generates a secret key sk_Γ on the basis of input of the public key pk, the master secret key sk and the attribute set Γ. An encryption device 2 generates a ciphered text ct on the basis of input of the public key pk, a plain text m and the access structure S. A decryption device 3 generates the plain text m on the basis of input of the public key pk, the secret key sk_Γ and the ciphered text ct.;COPYRIGHT: (C)2014,JPO&INPIT