Provably Secure Partially Blind Signatures
CRYPTO '00 Proceedings of the 20th 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
Programmable Hash Functions and Their Applications
CRYPTO 2008 Proceedings of the 28th Annual conference on Cryptology: Advances in Cryptology
Efficient non-interactive proof systems for bilinear groups
EUROCRYPT'08 Proceedings of the theory and applications of cryptographic techniques 27th annual international conference on Advances in cryptology
Structure-preserving signatures and commitments to group elements
CRYPTO'10 Proceedings of the 30th annual conference on Advances in cryptology
Signatures on randomizable ciphertexts
PKC'11 Proceedings of the 14th international conference on Practice and theory in public key cryptography conference on Public key cryptography
Round optimal blind signatures
CRYPTO'11 Proceedings of the 31st annual conference on Advances in cryptology
Efficient identity-based encryption without random oracles
EUROCRYPT'05 Proceedings of the 24th annual international conference on Theory and Applications of Cryptographic Techniques
Round-optimal composable blind signatures in the common reference string model
CRYPTO'06 Proceedings of the 26th annual international conference on Advances in Cryptology
Compact group signatures without random oracles
EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
Efficient blind and partially blind signatures without random oracles
TCC'06 Proceedings of the Third conference on Theory of Cryptography
Round-Optimal privacy-preserving protocols with smooth projective hash functions
TCC'12 Proceedings of the 9th international conference on Theory of Cryptography
Beyond the limitation of prime-order bilinear groups, and round optimal blind signatures
TCC'12 Proceedings of the 9th international conference on Theory of Cryptography
Compact round-optimal partially-blind signatures
SCN'12 Proceedings of the 8th international conference on Security and Cryptography for Networks
Compact round-optimal partially-blind signatures
SCN'12 Proceedings of the 8th international conference on Security and Cryptography for Networks
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Partially-blind signatures find many applications in the area of anonymity, such as in e-cash or e-voting systems. They extend classical blind signatures, with a signed message composed of two parts: a public one (common to the user and the signer) and a private one (chosen by the user, and blindly signed). The signer cannot link later the message-signature to the initial interaction with the user, among other signatures on messages with the same public part. This paper presents a one-round partially-blind signature which achieves perfect blindness in the standard model using a Common Reference String, under classical assumptions: CDH and DLin assumptions in symmetric groups, and similar ones in asymmetric groups. This scheme is more efficient than the previous ones: reduced round complexity and communication complexity, but still weaker complexity assumptions. A great advantage is also to end up with a standard Waters signature, which is quite short. In addition, in all the previous schemes, the public part required a prior agreement between the parties on the public part of the message before running the blind signature protocol. Our protocol does not require such pre-processing: the public part can be chosen by the signer only. Our scheme even allows multiple messages provided from independent sources to be blindly signed. These messages can either be concatenated or aggregated by the signer, without learning any information about them, before returning the blind signature to the recipient. For the aggregation (addition of the messages), we provide a new result, of independent interest, about the Waters hash function over non binary-alphabets.