On Resolving Key Escrow Problem in HIBE and HIBS

A HIBE scheme with independent delegation are free from Key Escrow Problem that is inherent in HIBE, given the root PKG is unconditionally trusted. We propose a new technique Identifier Discrimination for composing private keys for entities in hierarchy. With the technique, we construct a HIBE scheme under Decisional Bilinear Diffie-Helleman (DBDH) assumption in standard model with independent delegation, in which the privilege of generating private keys for each individual entity is delegated by the root PKG to any of its ancestors through authorization, that we call Authorization Delegation. Moreover, basing on Naor transformation of an identity-based signature (IBS) out of an IBE, we build a new hierarchical IBS (HIBS) scheme from our HIBE scheme. Being unable to generate a private key for any of its descendants, an entity cannot sign messages on behalf of any of its descendants, which guarantees that authenticity and non-repudiation properties are achieved in HIBS setting.

[1]  Dan Boneh,et al.  Short Signatures Without Random Oracles , 2004, EUROCRYPT.

[2]  Dan Boneh,et al.  Hierarchical Identity Based Encryption with Constant Size Ciphertext , 2005, EUROCRYPT.

[3]  Craig Gentry,et al.  Hierarchical ID-Based Cryptography , 2002, ASIACRYPT.

[4]  Dan Boneh,et al.  Efficient Selective-ID Secure Identity Based Encryption Without Random Oracles , 2004, IACR Cryptol. ePrint Arch..

[5]  Matthew K. Franklin,et al.  Identity-Based Encryption from the Weil Pairing , 2001, CRYPTO.

[6]  Florian Hess,et al.  Efficient Identity Based Signature Schemes Based on Pairings , 2002, Selected Areas in Cryptography.

[7]  Allison Bishop,et al.  New Techniques for Dual System Encryption and Fully Secure HIBE with Short Ciphertexts , 2010, IACR Cryptol. ePrint Arch..

[8]  Dan Boneh,et al.  Short Signatures Without Random Oracles and the SDH Assumption in Bilinear Groups , 2008, Journal of Cryptology.

[9]  Ben Lynn,et al.  Toward Hierarchical Identity-Based Encryption , 2002, EUROCRYPT.

[10]  Brent Waters,et al.  Dual System Encryption: Realizing Fully Secure IBE and HIBE under Simple Assumptions , 2009, IACR Cryptol. ePrint Arch..

[11]  Hovav Shacham,et al.  Short Signatures from the Weil Pairing , 2001, J. Cryptol..

[12]  Kenneth G. Paterson,et al.  ID-based Signatures from Pairings on Elliptic Curves , 2002, IACR Cryptol. ePrint Arch..

[13]  Dan Boneh,et al.  Efficient Selective Identity-Based Encryption Without Random Oracles , 2011, Journal of Cryptology.