Paper 2019/720
Leveraging Linear Decryption: Rate-1 Fully-Homomorphic Encryption and Time-Lock Puzzles
Zvika Brakerski and Nico Döttling and Sanjam Garg and Giulio Malavolta
Abstract
We show how to combine a fully-homomorphic encryption scheme with linear decryption and a linearly-homomorphic encryption schemes to obtain constructions with new properties. Specifically, we present the following new results. (1) Rate-1 Fully-Homomorphic Encryption: We construct the first scheme with message-to-ciphertext length ratio (i.e., rate) $1-\sigma$ for $\sigma = o(1)$. Our scheme is based on the hardness of the Learning with Errors (LWE) problem and $\sigma$ is proportional to the noise-to-modulus ratio of the assumption. Our building block is a construction of a new high-rate linearly-homomorphic encryption. One application of this result is the first general-purpose secure function evaluation protocol in the preprocessing model where the communication complexity is within additive factor of the optimal insecure protocol. (2) Fully-Homomorphic Time-Lock Puzzles: We construct the first time-lock puzzle where one can evaluate any function over a set of puzzles without solving them, from standard assumptions. Prior work required the existence of sub-exponentially hard indistinguishability obfuscation.
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- Preprint. MINOR revision.
- Keywords
- Fully-Homomorphic EncryptionHigh-RateTime-Lock Puzzles
- Contact author(s)
- giulio malavolta @ hotmail it,nico doettling @ gmail com,sanjamg @ berkeley edu,zvika brakerski @ weizmann ac il
- History
- 2019-06-18: revised
- 2019-06-18: received
- See all versions
- Short URL
- https://ia.cr/2019/720
- License
-
CC BY