Encrypted Search Index for Poly-Logarithmic Range Queries

The patent applies preliminary action by pre-processing encrypted data into a structured search index with sorted encrypted values and corresponding position information before query execution. This pre-organized structure enables efficient range queries without decryption, resolving the contradiction by preparing the data in advance for fast encrypted searching while maintaining privacy.

The patent replaces the mechanical decryption-and-search approach with an encrypted-domain search mechanism. Instead of decrypting data to perform searches, the system maintains encrypted data in a sorted structure and performs comparisons directly on ciphertexts using cryptographic comparison functions, substituting the traditional mechanical process with a cryptographic one that preserves privacy while enabling efficiency.

The patent extracts only the necessary minimum information for query execution by performing all search operations directly on encrypted data without extracting plaintext values. The search index stores encrypted values with position mappings, allowing range queries to be executed on ciphertexts alone, extracting no additional plaintext information and thus preventing information leakage while maintaining functionality.

The patent introduces encrypted position mappings as an intermediary between the encrypted data values and the query results. This intermediary layer allows the system to return correct query results without exposing plaintext relationships or additional information, as the position mappings operate entirely in the encrypted domain and reveal no semantic information about the underlying data.