Identity-based cryptosystems and signature schemes
Proceedings of CRYPTO 84 on Advances in cryptology
Communications of the ACM
Efficient Identity Based Signature Schemes Based on Pairings
SAC '02 Revised Papers from the 9th Annual International Workshop on Selected Areas in Cryptography
CRYPTO '89 Proceedings of the 9th Annual International Cryptology Conference on Advances in Cryptology
Key-Insulated Public Key Cryptosystems
EUROCRYPT '02 Proceedings of the International Conference on the Theory and Applications of Cryptographic Techniques: Advances in Cryptology
Applications of Multiple Trust Authorities in Pairing Based Cryptosystems
InfraSec '02 Proceedings of the International Conference on Infrastructure Security
An Identity-Based Signature from Gap Diffie-Hellman Groups
PKC '03 Proceedings of the 6th International Workshop on Theory and Practice in Public Key Cryptography: Public Key Cryptography
Strong Key-Insulated Signature Schemes
PKC '03 Proceedings of the 6th International Workshop on Theory and Practice in Public Key Cryptography: Public Key Cryptography
Secure key issuing in ID-based cryptography
ACSW Frontiers '04 Proceedings of the second workshop on Australasian information security, Data Mining and Web Intelligence, and Software Internationalisation - Volume 32
Certificate-based encryption and the certificate revocation problem
EUROCRYPT'03 Proceedings of the 22nd international conference on Theory and applications of cryptographic techniques
Identity-Based hierarchical strongly key-insulated encryption and its application
ASIACRYPT'05 Proceedings of the 11th international conference on Theory and Application of Cryptology and Information Security
A strong identity based key-insulated cryptosystem
EUC'06 Proceedings of the 2006 international conference on Emerging Directions in Embedded and Ubiquitous Computing
Identity based key insulated signature
ISPEC'06 Proceedings of the Second international conference on Information Security Practice and Experience
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Standard identity-based cryptosystems typically rely on the assumption that secret keys are kept perfectly secure. However, in practice, there are two threats to the key security in identity-based cryptosystems. One inherent problem is key escrow, that is, the Key Generation Center (KGC) always knows a user's secret key and the malicious KGC can impersonate the user. Meanwhile, another threat is that a user's secret key may be exposed to an adversary in an insecure device, and key exposure typically means that security is entirely lost. At present, there is no solution that can simultaneously solve both of above problems. In this paper, we first present a secure key issuing and updating model for identity-based cryptosystems. Our suggestion is an intermediate between the identity-based key insulation and distributing authorities approach, and can simultaneously solve both key escrow and key exposure problems. We formalize the definition and security notion of the corresponding encryption scheme (IBKUE) and signature scheme (IBKUS), and then propose an IBKUE scheme based on Boneh-Franklin's scheme [2] and an IBKUS scheme based on Cha-Cheon's scheme [9]. Both of the schemes are secure in the remaining time periods against an adversary who compromises the KGC and obtains a user's secret key for the time periods of its choice. All the schemes in this paper are provably secure in the random oracle model.