Hidden Identity-Based Signatures

This paper introduces Hidden Identity-based Signatures (Hidden-IBS), a type of digital signatures that provide mediated signer-anonymity on top of Shamir's Identity-based signatures. The motivation of our new signature primitive is to resolve an important issue with the kind of anonymity offered by "group signatures" where it is required that either the group membership list is public or that the opening authority is dependent on the group manager for its operation. Contrary to this, Hidden-IBS do not require the maintenance of a group membership list and they enable an opening authority that is totally independent of the group manager. As we argue this makes Hidden-IBS much more attractive than group signatures for a number of applications. In this paper, we provide a formal model of Hidden-IBS as well as two efficient constructions that realize the new primitive. Our elliptic curve construction that is based on the SDH/DLDH assumptions produces signatures that are merely 4605 bits long and can be implemented very efficiently. To demonstrate the power of the new primitive, we apply it to solve a problem of current onion-routing systems focusing on the Tor system in particular. Posting through Tor is currently blocked by sites such as Wikipedia due to the real concern that anonymous channels can be used to vandalize online content. By injecting a Hidden-IBS inside the header of an HTTP POST request and requiring the exit-policy of Tor to forward only properly signed POST requests, we demonstrate how sites like Wikipedia may allow anonymous posting while being ensured that the recovery of (say) the IP address of a vandal would be still possible through a dispute resolution system. Using our new Hidden-IBS primitive in this scenario allows to keep the listing of identities (e.g., IP addresses) of Tor users computationally hidden while maintaining an independent Opening Authority which would not have been possible with previous approaches.

[1]  Tsz Hon Yuen,et al.  Group Signature Where Group Manager, Members and Open Authority Are Identity-Based , 2005, ACISP.

[2]  Hovav Shacham,et al.  Group signatures with verifier-local revocation , 2004, CCS '04.

[3]  Yvo Desmedt,et al.  Threshold Cryptosystems , 1989, CRYPTO.

[4]  Jan Camenisch,et al.  A Group Signature Scheme with Improved Efficiency , 1998, ASIACRYPT.

[5]  Jan Camenisch,et al.  Group Signatures: Better Efficiency and New Theoretical Aspects , 2004, SCN.

[6]  Jan Camenisch,et al.  Separability and Efficiency for Generic Group Signature Schemes , 1999, CRYPTO.

[7]  Gene Tsudik,et al.  Some Open Issues and New Directions in Group Signatures , 1999, Financial Cryptography.

[8]  David Naccache,et al.  On blind signatures and perfect crimes , 1992, Comput. Secur..

[9]  Paul F. Syverson,et al.  Hiding Routing Information , 1996, Information Hiding.

[10]  Jan Camenisch,et al.  Signature Schemes and Anonymous Credentials from Bilinear Maps , 2004, CRYPTO.

[11]  Aggelos Kiayias,et al.  Group Signatures with Efficient Concurrent Join , 2005, EUROCRYPT.

[12]  Jan Camenisch,et al.  Efficient Group Signature Schemes for Large Groups (Extended Abstract) , 1997, CRYPTO.

[13]  Marc Joye,et al.  A Practical and Provably Secure Coalition-Resistant Group Signature Scheme , 2000, CRYPTO.

[14]  Jan Camenisch,et al.  A Signature Scheme with Efficient Protocols , 2002, SCN.

[15]  David Chaum,et al.  Group Signatures , 1991, EUROCRYPT.

[16]  Yiannis Tsiounis,et al.  "Indirect Discourse Proof": Achieving Efficient Fair Off-Line E-cash , 1996, ASIACRYPT.

[17]  Ueli Maurer,et al.  Digital Payment Systems with Passive Anonymity-Revoking Trustees , 1996, ESORICS.

[18]  Aggelos Kiayias,et al.  Efficient Secure Group Signatures with Dynamic Joins and Keeping Anonymity Against Group Managers , 2005, Mycrypt.

[19]  Aggelos Kiayias,et al.  Advances in Cryptology - EUROCRYPT 2004 , 2004 .

[20]  Pascal Paillier,et al.  Public-Key Cryptosystems Based on Composite Degree Residuosity Classes , 1999, EUROCRYPT.

[21]  Mihir Bellare,et al.  Foundations of Group Signatures: The Case of Dynamic Groups , 2005, CT-RSA.

[22]  Joe Kilian,et al.  Identity Escrow , 1998, CRYPTO.

[23]  Brent Waters,et al.  Compact Group Signatures Without Random Oracles , 2006, EUROCRYPT.

[24]  J. Pollard.  A monte carlo method for factorization , 1975 .

[25]  Jan Camenisch,et al.  Practical Group Signatures without Random Oracles , 2005, IACR Cryptol. ePrint Arch..

[26]  Jan Camenisch,et al.  An Identity Escrow Scheme with Appointed Verifiers , 2001, CRYPTO.

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

[28]  Hovav Shacham,et al.  Short Group Signatures , 2004, CRYPTO.

[29]  Reihaneh Safavi-Naini,et al.  Efficient and Provably Secure Trapdoor-Free Group Signature Schemes from Bilinear Pairings , 2004, ASIACRYPT.

[30]  Giuseppe Ateniese,et al.  Efficient Group Signatures without Trapdoors , 2003, ASIACRYPT.

[31]  Jan Camenisch,et al.  Efficient and Generalized Group Signatures , 1997, EUROCRYPT.

[32]  D. Boneh,et al.  Short Signatures from the Weil Pairing , 2001, Journal of Cryptology.

[33]  Jan Camenisch,et al.  Dynamic Accumulators and Application to Efficient Revocation of Anonymous Credentials , 2002, CRYPTO.

[34]  Shouhuai Xu,et al.  Accumulating Composites and Improved Group Signing , 2003, ASIACRYPT.

[35]  Lidong Chen,et al.  New Group Signature Schemes (Extended Abstract) , 1994, EUROCRYPT.

[36]  Adi Shamir,et al.  Identity-Based Cryptosystems and Signature Schemes , 1984, CRYPTO.

[37]  Hugo Krawczyk,et al.  Secure Distributed Key Generation for Discrete-Log Based Cryptosystems , 1999, EUROCRYPT.

[38]  Dawn Xiaodong Song,et al.  Quasi-Efficient Revocation in Group Signatures , 2002, Financial Cryptography.

[39]  Nick Mathewson,et al.  Tor: The Second-Generation Onion Router , 2004, USENIX Security Symposium.

[40]  Jan Camenisch,et al.  Practical Verifiable Encryption and Decryption of Discrete Logarithms , 2003, CRYPTO.

[41]  Jun Furukawa,et al.  Group Signatures with Separate and Distributed Authorities , 2004, SCN.

[42]  Dawn Xiaodong Song,et al.  Practical forward secure group signature schemes , 2001, CCS '01.

[43]  Hideki Imai,et al.  An Efficient Group Signature Scheme from Bilinear Maps , 2005, ACISP.

[44]  Aggelos Kiayias,et al.  Extracting Group Signatures from Traitor Tracing Schemes , 2003, EUROCRYPT.

[45]  Mihir Bellare,et al.  Foundations of Group Signatures: Formal Definitions, Simplified Requirements, and a Construction Based on General Assumptions , 2003, EUROCRYPT.