Abstract. Encryption of data using multiple, independent encryption schemes ("multiple encryption") has been suggested in a variety of contexts, and can be used, for example, to protect against partial key exposure or cryptanalysis, or to enforce threshold access to data. Most prior work on this subject has focused on the security of multiple encryption against chosen-plaintext attacks, and has shown constructions secure in this sense based on the chosen-plaintext security of the component schemes. Subsequent work has sometimes assumed that these solutions are also secure against chosen-ciphertext attacks when component schemes with stronger security properties are used. Unfortunately, this intuition is false for all existing multiple encryption schemes. Here, in addition to formalizing the problem of chosen-ciphertext security for multiple encryption, we give simple, efficient, and generic constructions of multiple encryption schemes secure against chosen-ciphertext attacks (based on any component schemes secure against such attacks) in the standard model. We also give a more efficient construction from any (hierarchical) identity-based encryption scheme secure against selectiveidentity chosen plaintext attacks. Finally, we discuss a wide range of applications for our proposed schemes.
Recently, Dodis and Katz REF have addressed the chosen ciphertext security of multiple encryptions in the general case, and have proposed generic constructions which are semantically secure.
Chosen-Ciphertext Security of Multiple Encryption
In TCC’05, LNCS 3378
Computer Science