One-Shot Secure Aggregation Using Homomorphic Key Summation
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Solution Overview
Problem
Existing secure aggregation protocols in distributed systems face challenges such as synchronization latency, integrity verification, scalability, and managing key distribution, especially in environments with distrustful parties and clients with limited resources.
Innovation Solution
A one-shot secure aggregation protocol using key-additive homomorphic encryption (KAHE) and additive homomorphic encryption (AHE) schemes, allowing clients to submit inputs without synchronization, with a decentralized decryptor and verifier ensuring privacy and correctness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional secure aggregation protocols are used, then privacy and security are maintained, but synchronization latency increases and scalability deteriorates
Solution Approach 1:
The patent segments the aggregation process into independent one-shot client submissions that do not require synchronization. Each client can submit their encrypted input independently to the server, eliminating the need for coordinated synchronization rounds while maintaining security through the cryptographic protocol.
Solution Approach 2:
The patent uses preliminary key generation and distribution where clients receive public keys before submission and the server pre-configures aggregation parameters. This preliminary setup enables one-shot submissions without requiring real-time synchronization, as all cryptographic materials are prepared in advance.
2Reliability
If traditional secure aggregation protocols are used, then privacy is maintained, but device complexity and key management burden increase
Solution Approach 1:
The patent introduces a key distribution server as an intermediary that handles all key generation, distribution, and management operations. Clients simply receive public keys from this intermediary without needing to manage complex key pairs themselves, significantly reducing device complexity while maintaining cryptographic privacy guarantees.
Solution Approach 2:
The protocol enables clients to independently encrypt their inputs using received public keys and submit them without requiring complex interactions with other clients or the server. Each client serves themselves by performing local encryption and submission, reducing the overall system complexity.
3Reliability
If traditional secure aggregation protocols are used, then correctness is verified, but scalability deteriorates in large client groups
Solution Approach 1:
The patent extracts the verification function into a separate zero-knowledge proof mechanism that operates independently of the main aggregation process. The server generates proofs that aggregation was performed correctly without requiring interactive verification with all clients, enabling scalability to large client groups while maintaining integrity verification.
Data Source
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AI summary
Methods and systems for implementing secure aggregation with one-shot clients are described herein. A server receives, from each client, (i) an encrypted client input represented by a client input encrypted by a Key-Additive Homomorphic Encryption (KAHE) scheme using a client key, and (ii) an encrypted client key represented by the client key encrypted by an Additive Homomorphic Encryption (AHE) scheme using a public key received by the client from a decryptor. The server adds the encrypted client input to a combination (e.g., a running sum) of encrypted client inputs received from at least some of the clients. The server further adds the encrypted client key to a combination (e.g., a running sum) of encrypted client keys received from the clients which supplied their client inputs to the server. The server then transmits, to the decryptor, the running sum of encrypted client keys. In response, the server receives, from the decryptor, a decrypted key produced by decrypting, using a secret key corresponding to the public key, the running sum of encrypted client keys. The server then decrypts, using the decrypted key, the running sum of encrypted client inputs.