Zero-knowledge undeniable signatures (extended abstract)
EUROCRYPT '90 Proceedings of the workshop on the theory and application of cryptographic techniques on Advances in cryptology
Random oracles are practical: a paradigm for designing efficient protocols
CCS '93 Proceedings of the 1st ACM conference on Computer and communications security
Convertible Undeniable Signatures
CRYPTO '90 Proceedings of the 10th Annual International Cryptology Conference on Advances in Cryptology
Efficient Group Signature Schemes for Large Groups (Extended Abstract)
CRYPTO '97 Proceedings of the 17th Annual International Cryptology Conference on Advances in Cryptology
ASIACRYPT '96 Proceedings of the International Conference on the Theory and Applications of Cryptology and Information Security: Advances in Cryptology
CRYPTO '89 Proceedings of the 9th Annual International Cryptology Conference on Advances in Cryptology
New convertible undeniable signature schemes
EUROCRYPT'96 Proceedings of the 15th annual international conference on Theory and application of cryptographic techniques
A generic construction for universally-convertible undeniable signatures
CANS'07 Proceedings of the 6th international conference on Cryptology and network security
Convertible undeniable proxy signatures: security models and efficient construction
WISA'07 Proceedings of the 8th international conference on Information security applications
On the security of a group signcryption scheme from distributed signcryption scheme
CANS'05 Proceedings of the 4th international conference on Cryptology and Network Security
Provably secure pairing-based convertible undeniable signature with short signature length
Pairing'07 Proceedings of the First international conference on Pairing-Based Cryptography
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Group undeniable signatures are like ordinary group signatures except that verifying signatures needs the help of the group manager. In this paper, we propose a convertible group undeniable signature scheme in which the group manager can turn all or selective signatures, which are originally group undeniable signatures, into ordinary group signatures without compromising security of the secret key needed to generate signatures. The proposed scheme also allows the group manager to delegate the ability to confirm and deny to a limited set of parties without providing them the capability of generating signatures. For business applications, convertible group undeniable signatures can be widely used to validate price lists, press release or digital contracts when the signatures are commercially sensitive or valuable to a competitor. Our scheme is unforgeable, signature-simulatable and coalition-resistant. The confirmation and denial protocols are also zero-knowledge. Furthermore, the time, space and communication complexity are independent of the group size.