Identity-based cryptosystems and signature schemes
Proceedings of CRYPTO 84 on Advances in cryptology
Public-key cryptosystems provably secure against chosen ciphertext attacks
STOC '90 Proceedings of the twenty-second annual ACM symposium on Theory of computing
Random oracles are practical: a paradigm for designing efficient protocols
CCS '93 Proceedings of the 1st ACM conference on Computer and communications security
Identity-Based Encryption from the Weil Pairing
CRYPTO '01 Proceedings of the 21st Annual International Cryptology Conference on Advances in Cryptology
A Practical Public Key Cryptosystem Provably Secure Against Adaptive Chosen Ciphertext Attack
CRYPTO '98 Proceedings of the 18th Annual International Cryptology Conference on Advances in Cryptology
Key-Privacy in Public-Key Encryption
ASIACRYPT '01 Proceedings of the 7th International Conference on the Theory and Application of Cryptology and Information Security: Advances in Cryptology
An Identity Based Encryption Scheme Based on Quadratic Residues
Proceedings of the 8th IMA International Conference on Cryptography and Coding
Proceedings of the 2003 ACM workshop on Privacy in the electronic society
Concealing complex policies with hidden credentials
Proceedings of the 11th ACM conference on Computer and communications security
Chosen-Ciphertext Security from Identity-Based Encryption
SIAM Journal on Computing
Security and Anonymity of Identity-Based Encryption with Multiple Trusted Authorities
Pairing '08 Proceedings of the 2nd international conference on Pairing-Based Cryptography
Improved efficiency for CCA-secure cryptosystems built using identity-based encryption
CT-RSA'05 Proceedings of the 2005 international conference on Topics in Cryptology
Searchable encryption revisited: consistency properties, relation to anonymous IBE, and extensions
CRYPTO'05 Proceedings of the 25th annual international 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
Practical identity-based encryption without random oracles
EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
Identity based encryption: Progress and challenges
Information Security Tech. Report
Acquiring key privacy from data privacy
Inscrypt'10 Proceedings of the 6th international conference on Information security and cryptology
Anonymous broadcast encryption: adaptive security and efficient constructions in the standard model
PKC'12 Proceedings of the 15th international conference on Practice and Theory in Public Key Cryptography
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In the setting of identity-based encryption with multiple trusted authorities, TA anonymity formally models the inability of an adversary to distinguish two ciphertexts corresponding to the same message and identity, but generated using different TA master public-keys. This security property has applications in the prevention of traffic analysis in coalition networking environments. In this paper, we examine the implications of TA anonymity for key-privacy for normal public-key encryption (PKE) schemes. Key-privacy for PKE captures the requirement that ciphertexts should not leak any information about the public-keys used to perform encryptions. Thus key-privacy guarantees recipient anonymity for a PKE scheme. Canetti, Halevi and Katz (CHK) gave a generic transform which constructs an IND-CCA secure PKE scheme using an identity-based encryption (IBE) scheme that is selective-id IND-CPA secure and a strongly secure one-time signature scheme. Their transform works in the standard model (i.e. does not require the use of random oracles). Here, we prove that if the underlying IBE scheme in the CHK transform is TA anonymous, then the resulting PKE scheme enjoys key-privacy. Whilst IND-CCA secure, key-private PKE schemes are already known in the standard-model, our result gives the first generic method of constructing a key-private PKE scheme in the standard model. We then go on to investigate the TA anonymity of multi-TA versions of well-known standard model secure IBE schemes. In particular, we prove the TA anonymity and selective-id IND-CPA security of a multi-TA version of Gentry's IBE scheme. Applying the CHK transform, we obtain a new, efficient key- private, IND-CCA secure PKE scheme in the standard model.