Database Proxy Security Budget for Persistent Adversaries
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Solution Overview
Problem
Data stored with a service provider is vulnerable to leakage by adversaries, including snapshot and persistent adversaries, who can infer information from queries and responses, and existing encryption techniques are either ineffective or impractical for dynamic databases.
Innovation Solution
A database proxy acts as an intermediary between clients and the service provider, batching queries, transforming them using order-preserving encryption, and managing a security budget to limit data leakage, ensuring protection against both snapshot and persistent adversaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored with a service provider in encrypted form, then data confidentiality is improved, but adversaries can still infer information from queries and responses
Solution Approach 1:
The patent introduces a database proxy as an intermediary component between clients and the service provider. This proxy transforms client queries into modified queries before sending them to the service provider, and transforms responses back before returning to clients. The proxy maintains a security budget that tracks and limits information leakage to adversaries, effectively mediating between the need for encrypted storage and the risk of inference attacks.
Solution Approach 2:
The patent transforms queries by modifying their parameters before execution. Specifically, it transforms range queries into point queries with modified parameters, and transforms point queries into range queries with expanded parameters. This parameter transformation changes the nature of the queries executed on encrypted data, preventing adversaries from inferring information through pattern recognition while still allowing useful queries to be performed.
2Reliability
If existing encryption techniques are used on dynamic databases, then data protection is improved, but the techniques are either ineffective or impractical
Solution Approach 1:
The patent implements a dynamic security budget management system that adapts to changing database conditions. The security budget is updated based on the type of queries executed, the state of the database, and the adversary's knowledge. This dynamic approach allows the system to maintain security guarantees while supporting dynamic database operations such as inserts, deletes, and updates, making the encryption technique practical for real-world dynamic databases.
Solution Approach 2:
The patent segments the database operations into different query types (point queries, range queries, insert operations, delete operations) and applies specific transformation strategies to each segment. This segmentation allows the system to handle different operations with appropriate security measures, making the overall encryption technique more manageable and practical for dynamic databases with diverse operation types.
3Ease of operation
If queries are executed on encrypted data, then data accessibility is improved, but information leakage to adversaries increases
Solution Approach 1:
The patent transforms point queries into range queries with expanded parameters, executing a broader query than strictly necessary. This excessive action retrieves more data than the client explicitly requested, but the additional data is noise that prevents adversaries from inferring information about the actual target. The security budget accounts for this partial leakage, trading controlled information release for enhanced security.
Solution Approach 2:
The patent converts the potential harm of information leakage into a benefit by using the leaked information as security noise. The transformed queries intentionally leak some information about the query structure and data ranges, but this leakage is unpredictable and uncontrollable for adversaries, effectively serving as cryptographic noise that protects against inference attacks while maintaining query functionality.
Data Source
AI summary
One embodiment provides a method, including: receiving, at a database proxy acting as an intermediary between a plurality of database clients and a service provider providing data management services for the plurality of database clients, a set of queries, of at least one of the plurality of database clients, for data stored at the service provider in an encrypted form, wherein the database proxy maintains a security budget defining a maximum threshold amount of data leakage for the plurality of database clients; batching the set of queries into query batches; transforming, for each query batch, each query within the query batch, wherein the transforming includes changing the query to reduce data leakage; performing, responsive to transforming each query within the query batch, a transformation on each of the query batches to reduce data leakage; executing, at the database proxy and utilizing an order-preserving encryption algorithm, the query batches; and calculating a remaining security budget based upon data leakage resulting from the executing.