Cryptology ePrint Archive: Report 2015/1035

CARIBE: Cascaded IBE for Maximum Flexibility and User-side Control

Britta Hale and Christopher Carr and Danilo Gligoroski

Abstract: Mass surveillance and a lack of end-user encryption, coupled with a growing demand for key escrow under legal oversight and certificate authority security concerns, raise the question of the appropriateness of continued general dependency on PKI. Under this context, we examine Identity-Based Encryption (IBE) as an alternative to public-key encryption. Cascade encryption, or sequential multiple encryption, is the concept of layering encryption such that the ciphertext from one encryption step is the plaintext of the next. We describe CARIBE, a cascaded IBE scheme, for which we also provide a cascaded CCA security experiment, IND-ID-C.CCA, and prove its security in the computational model. CARIBE combines the ease-of-use of IBE with key escrow, limited to the case when the entire set of participating PKGs collaborate. Furthermore, we describe a particular CARIBE scheme, CARIBE-S, where the receiver is a self-PKG one of the several PKGs included in the cascade. CARIBE-S inherits IND-ID-C.CCA from CARIBE, and avoids key escrow entirely. In essence, CARIBE-S offers the maximum flexibility of the IBE paradigm and gives the users complete control without the key escrow problem.

Category / Keywords: public-key cryptography /identity-based encryption, cascade ciphers, PKI, practice-oriented provable security, mass-surveillance

Original Publication (with major differences): MyCrypt 2016

Date: received 26 Oct 2015, last revised 16 Jan 2017

Contact author: ccarr at item ntnu no

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Note: Extensions and discussion additions.

Version: 20170116:140442 (All versions of this report)

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