Identity-Based Conditional Broadcast Proxy Re-encryption Based on SM9

Key Points

• The aim is to develop a proxy re-encryption scheme that allows conditional broadcast and enhances privacy for multiple data requesters.
• Introduce a new scheme called SM9-IB-CBPRE using identity-based encryption.
• Embed condition sets into ciphertexts and re-encryption keys for fine-grained access control.
• Utilize Lagrange interpolation to hide requester information.
• Design an extended version SM9-IB-CBPRE+ for flexible attribute-based access control.
• Conduct security and performance analyses under the random oracle model.
• The proposed scheme effectively prevents privacy leakage while supporting any number of data requesters.
• Security analysis shows resilience against chosen plaintext and collusion attacks.
• Performance is comparable to existing methods, with improvements in functionality and usability.