Updating Token Verification for Post-Quantum Key Rotation
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Solution Overview
Problem
Existing encryption key rotation methods are inefficient, expose plaintext during frequent key changes, require extensive computational resources, and are vulnerable to quantum computers, lacking post-compromise security and validation mechanisms.
Innovation Solution
A homomorphic probabilistic encryption scheme using key-homomorphic and bi-homomorphic pseudorandom function families for secure, efficient, and verifiable key rotation, employing an updating token to rotate encryption keys without decrypting the underlying data, validated by predicting the Hamming distance between ciphertexts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional key rotation methods are used, then key updates can be performed, but plaintext is exposed during the rotation process and extensive computational resources are required
Solution Approach 1:
The patent introduces a re-encryption key as an intermediary element that enables key rotation without exposing plaintext. The re-encryption key allows transformation of ciphertext from one encryption key to another without requiring decryption, thus serving as a mediator that eliminates the security vulnerability of plaintext exposure during key rotation.
Solution Approach 2:
The patent generates re-encryption keys in advance before key rotation is needed. These pre-generated re-encryption keys are stored and ready for use, allowing rapid key rotation when needed without requiring computational resources to generate them at the moment of rotation, thus addressing both security and computational efficiency concerns.
2Reliability
If frequent key rotation is performed to prevent key exhaustion, then security is improved, but computational overhead increases and plaintext exposure risk increases
Solution Approach 1:
The re-encryption key acts as a computational intermediary that simplifies the key rotation process. Instead of requiring full decryption and re-encryption operations which are computationally intensive, the re-encryption key enables efficient transformation of ciphertext between different encryption keys, significantly reducing computational overhead for frequent rotations.
3Adaptability or versatility
If existing key rotation methods are used, then key updates can be performed, but the system is vulnerable to quantum computers and lacks post-compromise security
Solution Approach 1:
The patent changes the cryptographic parameters by using homomorphic encryption schemes that are quantum-resistant. This involves adopting encryption algorithms based on mathematical problems that are believed to be hard even for quantum computers, such as lattice-based cryptography or code-based cryptography, thereby providing forward-looking security adaptability.
4Ease of operation
If key rotation is performed without validation, then the process is simpler, but there is no mechanism to verify correct rotation
Solution Approach 1:
The patent implements a validation mechanism that provides feedback on whether key rotation was successful. This includes verifying that the re-encryption operation produced valid ciphertext and that the new encryption key is properly established, giving operators confidence that the rotation process completed correctly without adding significant complexity.
Data Source
AI summary
Certain aspects of the disclosure provide a method for verifiable key rotation of an encryption key. The method includes generating a ciphertext by encrypting a plaintext with a homomorphic probabilistic encryption scheme based on a first key. The method further includes generating an updating token based on a difference between the homomorphic probabilistic encryption scheme based on a second key and generating a second ciphertext by encrypting the first ciphertext with the updating token. The method further includes validating the key rotation by selecting a set of second ciphertext blocks from the second ciphertext.