Paper 2023/825
Oblivious Identity-based Encryption (IBE Secure Against an Adversarial KGC)
Abstract
Identity-Based Encryption (IBE) was introduced in order to reduce the cost associated with Public Key Infrastructure systems. IBE allows users to request a trusted Key Generation Centre (KGC) for a secret key on a given identity, without the need to manage public keys. However, one of the main concerns of IBE is that the KGC has the power to decrypt all ciphertexts as it has access to all (identity, secret key) pairs. To address this issue, Chow (PKC 2009) introduced a new security property against the KGC by employing a new trusted party called the Identity Certifying Authority (ICA). Emura et al. (ESORICS 2019) formalized this notion and proposed construction in the random oracle model. In this work, we first identify several existing IBE schemes where the KGC can decrypt a ciphertext even without knowing the receiver's identity. This paves the way for formalizing new capabilities for the KGC. We then propose a new security definition to capture an adversarial KGC including the newly identified capabilities and we remove the requirement of an additional trusted party. Finally, we propose a new IBE construction that allows users to ask the KGC for a secret key on an identity without leaking any information about the identity to the KGC that is provably secure in the standard model against an adversarial KGC and corrupted users. Our construction is achieved in the composite order pairing groups and requires essentially optimal parameters.
Metadata
- Available format(s)
-
PDF
- Category
- Public-key cryptography
- Publication info
- Preprint.
- Keywords
- Identity-based Encryptionkey escrow problempairing-based cryptography
- Contact author(s)
-
katerina mitrokotsa @ unisg ch
csayantan mukherjee @ gmail com
jenittomy @ gmail com - History
- 2023-06-06: approved
- 2023-06-02: received
- See all versions
- Short URL
- https://ia.cr/2023/825
- License
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CC BY
BibTeX
@misc{cryptoeprint:2023/825, author = {Katerina Mitrokotsa and Sayantan Mukherjee and Jenit Tomy}, title = {Oblivious Identity-based Encryption ({IBE} Secure Against an Adversarial {KGC})}, howpublished = {Cryptology {ePrint} Archive, Paper 2023/825}, year = {2023}, url = {https://eprint.iacr.org/2023/825} }