Identity-based cryptosystems and signature schemes
Proceedings of CRYPTO 84 on Advances in cryptology
On blind signatures and perfect crimes
Computers and Security
Digital Payment Systems with Passive Anonymity-Revoking Trustees
ESORICS '96 Proceedings of the 4th European Symposium on Research in Computer Security: Computer Security
Efficient Group Signature Schemes for Large Groups (Extended Abstract)
CRYPTO '97 Proceedings of the 17th Annual International Cryptology Conference on Advances in Cryptology
"Indirect Discourse Proof": Achieving Efficient Fair Off-Line E-cash
ASIACRYPT '96 Proceedings of the International Conference on the Theory and Applications of Cryptology and Information Security: Advances in Cryptology
Proceedings of the First International Workshop on Information Hiding
Group signatures with verifier-local revocation
Proceedings of the 11th ACM conference on Computer and communications security
Tor: the second-generation onion router
SSYM'04 Proceedings of the 13th conference on USENIX Security Symposium - Volume 13
Efficient and generalized group signatures
EUROCRYPT'97 Proceedings of the 16th annual international conference on Theory and application of cryptographic techniques
EUROCRYPT'03 Proceedings of the 22nd international conference on Theory and applications of cryptographic techniques
Efficient secure group signatures with dynamic joins and keeping anonymity against group managers
Mycrypt'05 Proceedings of the 1st international conference on Progress in Cryptology in Malaysia
An efficient group signature scheme from bilinear maps
ACISP'05 Proceedings of the 10th Australasian conference on Information Security and Privacy
Group signature where group manager, members and open authority are identity-based
ACISP'05 Proceedings of the 10th Australasian conference on Information Security and Privacy
Group signatures with separate and distributed authorities
SCN'04 Proceedings of the 4th international conference on Security in Communication Networks
Group signatures: better efficiency and new theoretical aspects
SCN'04 Proceedings of the 4th international conference on Security in Communication Networks
Foundations of group signatures: the case of dynamic groups
CT-RSA'05 Proceedings of the 2005 international conference on Topics in Cryptology
Group signatures with efficient concurrent join
EUROCRYPT'05 Proceedings of the 24th annual international conference on Theory and Applications of Cryptographic Techniques
Compact group signatures without random oracles
EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
Hidden attribute-based signatures without anonymity revocation
Information Sciences: an International Journal
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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.