Fully Homomorphic Encryption schemes (FHEs) and Functional Encryption schemes (FunctEs) have a tremendousimpact in cryptography both for the natural questions that they address and for the wide range of applications in which they have been (sometimes critically) used. In this work we put forth the notion of a Controllable Homomorphic Encryption scheme (CHES), a new primitive that includes features of both FHEs and FunctEs. In a CHES it is possible (similarly to a FHE) to homomorphically evaluate a ciphertext Ct= Enc(m) and a circuit C therefore obtaining Enc(C(m)) but only if (similarly to a FunctE) a token for C has been received from the owner of the secret key. We discuss difficulties in constructing a CHES and then show a construction based on any FunctE. As a byproduct our CHES also represents a FunctE supporting the re-encryption functionality and in that respect improves existing solutions.
Controlled homomorphic encryption: Definition and construction / Desmedt, Yvo; Iovino, Vincenzo; Persiano, Giuseppe; Visconti, Ivan. - 10323:(2017), pp. 107-129. (Intervento presentato al convegno 21st International Workshops on Financial Cryptography and Data Security, FC 2017 held in conjuction with 5th Workshop on Encrypted Computing and Applied Homomorphic Cryptography, WAHC 2017, 4th Workshop on Bitcoin and Blockchain Research, BITCOIN 2017, 2nd Workshop on Advances in Secure Electronic Voting Schemes, VOTING 2017, 1st Workshop on Trusted Smart Contracts, WTSC 2017 and 1st Workshop on Targeted Attacks, TA 2017 tenutosi a mlt) [10.1007/978-3-319-70278-0_7].
Controlled homomorphic encryption: Definition and construction
Persiano, Giuseppe;Visconti, Ivan
2017
Abstract
Fully Homomorphic Encryption schemes (FHEs) and Functional Encryption schemes (FunctEs) have a tremendousimpact in cryptography both for the natural questions that they address and for the wide range of applications in which they have been (sometimes critically) used. In this work we put forth the notion of a Controllable Homomorphic Encryption scheme (CHES), a new primitive that includes features of both FHEs and FunctEs. In a CHES it is possible (similarly to a FHE) to homomorphically evaluate a ciphertext Ct= Enc(m) and a circuit C therefore obtaining Enc(C(m)) but only if (similarly to a FunctE) a token for C has been received from the owner of the secret key. We discuss difficulties in constructing a CHES and then show a construction based on any FunctE. As a byproduct our CHES also represents a FunctE supporting the re-encryption functionality and in that respect improves existing solutions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
