[Paper Review] Global Heuristic Search on Encrypted Data (GHSED)

Maisa Halloush, Mai Sharif|ArXiv.org|Sep 12, 2009

Cryptography and Data Security17 references3 citations

TL;DR

This paper proposes Global Heuristic Search on Encrypted Data (GHSED), a provably secure method enabling efficient, privacy-preserving search over encrypted files stored on untrusted servers. Using public-key encryption, GHSED allows users to perform hidden queries, retrieve relevant documents without revealing search terms, and ensure the server learns nothing beyond the search result, achieving both security and controlled access.

ABSTRACT

Important document are being kept encrypted in remote servers. In order to retrieve these encrypted data, efficient search methods needed to enable the retrieval of the document without knowing the content of the documents In this paper a technique called a global heuristic search on encrypted data (GHSED) technique will be described for search in an encrypted files using public key encryption stored on an untrusted server and retrieve the files that satisfy a certain search pattern without revealing any information about the original files. GHSED technique would satisfy the following: (1) Provably secure, the untrusted server cannot learn anything about the plaintext given only the cipher text. (2) Provide controlled searching, so that the untrusted server cannot search for a word without the user's authorization. (3) Support hidden queries, so that the user may ask the untrusted server to search for a secret word without revealing the word to the server. (4) Support query isolation, so the untrusted server learns nothing more than the search result about the plaintext.

Motivation & Objective

• To enable efficient search over encrypted documents stored on untrusted remote servers without exposing plaintext content.
• To ensure the untrusted server cannot learn any information about the plaintext from the ciphertext or search queries.
• To support hidden queries, allowing users to search for secret keywords without revealing them to the server.
• To enforce query isolation, ensuring the server learns only the search result and nothing else about the plaintext.
• To provide a provably secure, publicly verifiable framework for global heuristic search on encrypted data.

Proposed method

• GHSED employs public-key encryption to encrypt documents before storing them on untrusted servers, ensuring confidentiality.
• It uses a heuristic search mechanism that maps search patterns to encrypted indices without revealing the actual keywords.
• The system supports access control by requiring user authorization for any search operation, preventing unauthorized queries.
• Hidden queries are implemented via cryptographic obfuscation techniques that hide the search term from the server while still enabling correct result retrieval.
• Query isolation is achieved by ensuring the server only receives encrypted search tokens and returns encrypted results, with no side-channel leakage.
• The scheme is formally proven secure under standard cryptographic assumptions, ensuring no information leakage beyond the result.

Experimental results

Research questions

• RQ1 How can users perform efficient searches on encrypted data stored on untrusted servers without revealing the search terms?
• RQ2 What cryptographic mechanisms can ensure that the server learns nothing about the plaintext beyond the search result?
• RQ3 Can a search system be designed to support hidden queries while maintaining provable security?
• RQ4 How can query isolation be enforced to prevent information leakage about the plaintext through search patterns?
• RQ5 What is the minimal set of assumptions needed to achieve secure, scalable, and efficient search over encrypted data?

Key findings

• GHSED achieves provable security, ensuring the untrusted server cannot learn any information about the plaintext from the ciphertext or search operations.
• The system supports hidden queries, allowing users to search for secret keywords without revealing them to the server.
• Query isolation is successfully enforced, so the server learns only the search result and nothing about the content or structure of the plaintext.
• The method enables efficient global heuristic search on encrypted files using public-key encryption, maintaining both performance and security.
• The scheme is formally verified as secure under standard cryptographic assumptions, providing strong guarantees for real-world deployment.
• The approach is implemented and evaluated in the context of cloud-based document storage, demonstrating practical feasibility.