Pre-Constrained Encryption
summary
Defines Pre-Constraint Encryption where an authority-generated decryption key K is limited to computing only a pre-authorized class of functions (and can delegate per-function keys SKF), not full plaintexts. Gives concrete constructions: constructions from LWE for identity-based PCE (all identities) and attribute-based PCE for point constraints*, and proves equivalence with indistinguishability obfuscation (IO) under assumptions. Builds the scheme from selective-security AB proofs using Boneh et al. style lattices, gadget matrices and a sample-right trapdoor trick, and compiles semi-malicious setup to malicious using secret sharing plus non-interactive witness-and-distinction proofs.
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chapters (16)
- 0:00Intro
- 0:33How does end-to-end encryption work?
- 5:15The Encryption Debate
- 5:49Is there a middle ground?
- 6:23Our Notion: Pre-Constrained Encryption
- 8:06Authority could be malicious!
- 12:57Authorized classes of functions: Examples
- 14:25Definition
- 17:48Useful feature: Key Delegation
- 19:20Special cases of PCE
- 20:55(Selected) Main Results: Informal summary
- 22:46PCE versus Functional Encryption
- 24:47Related Work
- 26:57Main Insight
- 30:14PCE for point constraints: Template
- 36:58Conclusion
