Secure Message Search Using Salted Token Indexing
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Solution Overview
Problem
Existing communication systems lack secure search functionality that protects sensitive information from intermediate parties, as they rely on untrusted communication servers that can exploit cryptographic trust, potentially revealing user communications.
Innovation Solution
Implementing a secure search method where messages are tokenized, transformed with salt values, and encrypted, allowing users to search encrypted messages without revealing intent to the communication server, using secure search modules on both client devices and the communication server to maintain message confidentiality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If messages are encrypted using cryptographic capabilities, then message confidentiality is improved, but search functionality deteriorates because encrypted messages cannot be searched
Solution Approach 1:
The message is segmented into individual tokens (words or meaningful units) before encryption. Each token is transformed separately using the salt value, creating a set of transformed tokens that can be independently indexed and searched without decrypting the entire message.
Solution Approach 2:
Tokens are transformed using the salt value before the message is encrypted. This preliminary transformation creates a searchable index of encrypted tokens that can be queried without requiring decryption of the full message, enabling search functionality to work on encrypted data.
2Ease of operation
If a communication server is used to facilitate communication, then ease of operation is improved, but security deteriorates because the server can exploit cryptographic trust to obtain unencrypted communications
Solution Approach 1:
The cryptographic trust requirement is extracted from the communication server. The server no longer needs cryptographic keys or trust relationships to secure communications, as security is achieved through salt-based token transformation that does not rely on server-held secrets.
Solution Approach 2:
A salt value acts as an intermediary between the client and server for search operations. The salt transforms tokens in a way that enables the server to perform searches on encrypted messages without needing to decrypt them or have cryptographic trust, thus mediating between security and search functionality.
3Adaptability or versatility
If tokens are transformed using salt values before encryption, then searchability of encrypted messages is improved, but device complexity increases due to additional transformation steps
Solution Approach 1:
The token transformation and message encryption processes are merged into a unified workflow. The salt-based token transformation is performed as part of the message processing pipeline before encryption, combining multiple security and search-enabling operations into a single integrated process rather than separate complex systems.
Data Source
AI summary
A communication server, interacting with an organization system having users that wish to communicate securely, provides secure communication capability to the users, without the communication server itself having access to unencrypted content of the user communications or to cryptographic keys that would allow the communication server to derive the unencrypted content. Thus, the communication server that provides the secure communication capability need not itself be trusted by the users with access to communicated content. To achieve this, the various entities communicate to exchange cryptographic keys in such a manner that the communication server never obtains usable copies of the cryptographic keys. Secure search capability is also provided by the client devices supplying a set of message tokens obtained by transformations that the communication server cannot replicate, and the communication server maintaining a search index storing the message tokens in association with the (encrypted) messages from which they were obtained.