Searchable Ciphertext Encryption Using Random Salt Obfuscation
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Solution Overview
Problem
Existing encryption methods face challenges in balancing data security with efficient searching and data leakage prevention, particularly in deterministic encryption, where identical plaintexts produce identical ciphertexts, enabling pattern recognition and compromising security.
Innovation Solution
A non-deterministic encryption method using exclusive OR operations with random salts and encryption keys to generate ciphertext, allowing secure searching by obscuring search terms and ciphertext with additional random salts, ensuring that plaintext remains secure during comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If deterministic encryption is used, then searching and indexing of encrypted data is facilitated, but third parties can derive information from ciphertexts through pattern recognition
Solution Approach 1:
The encryption process is segmented into multiple independent steps: generating a random salt, XORing the plaintext with the salt to create salted plaintext, then XORing the salted plaintext with the key to produce ciphertext. This segmentation allows the random salt to be stored separately from the ciphertext, enabling search functionality while maintaining security.
Solution Approach 2:
A random salt is introduced as an intermediary element between the plaintext and the encryption key. The salt acts as a mediator that obscures patterns in the ciphertext while still allowing deterministic search when the same salt is used. The salt is stored alongside the ciphertext and used during search operations to restore the ability to search without compromising security.
2Loss of information
If non-deterministic encryption is used, then data security is improved by preventing pattern recognition, but searching and indexing of encrypted data becomes difficult
Solution Approach 1:
A random salt is generated and applied to the plaintext before the actual encryption process. This preliminary action of salting creates a deterministic transformation that can be reversed during search operations, while the subsequent encryption with the key provides the non-deterministic security layer.
Solution Approach 2:
The encryption scheme changes its parameters by introducing a random salt that is stored with the ciphertext. This parameter change allows the system to switch between secure storage mode and search mode by controlling whether the salt is used during the search process, thus resolving the contradiction between security and searchability.
3Adaptability or versatility
If public key encryption is used, then encryption flexibility is improved, but third parties can guess plaintext by encrypting guesses and comparing results
Solution Approach 1:
The system adds another dimension to the encryption process by introducing a random salt that is perpendicular to the key space. This additional dimension (the salt) ensures that even with public key encryption, attackers cannot simply guess and check plaintexts because the salt creates a unique transformation for each encryption operation, making the search space exponentially larger.
Data Source
AI summary
The invention provides computer-implemented methods for encrypting data, searching ciphertext, and decrypting ciphertext, and data processing apparatuses, computer programs, and computer readable storage media for achieving the same. Encrypting data comprises salting and then encrypting ciphertext, both processes using a respective exclusive OR operation. Decryption is achieved by the same process in reverse. Searching the ciphertext is achieved by generating a modifier and salted search term, before modifying the ciphertext with the modifier and performing a bytewise comparison between the salted search term and the modified ciphertext.