Digital Cryptosystem Re-derivable Hybrid Keys
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Solution Overview
Problem
Existing digital cryptosystems face challenges in securely and efficiently managing digital keys, particularly when dealing with a large number of datasets, as using a single key diminishes security while generating and storing unique keys for each dataset is inefficient.
Innovation Solution
A digital cryptosystem that generates a master key for global use, derives a unique ephemeral key for each dataset using a stretched initialization vector and a master key, and encrypts the dataset, allowing the ephemeral key to be inaccessible after use while still being re-derivable for decryption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single key is used for all datasets, then key management efficiency is improved, but security is worsened
Solution Approach 1:
The system segments the key management structure by introducing a hierarchy where a master key is combined with unique per-dataset initialization vectors (IVs) to derive ephemeral keys. This segmentation allows efficient master key management while ensuring each dataset has unique cryptographic material, resolving the contradiction between efficiency and security.
Solution Approach 2:
The initialization vector (IV) acts as an intermediary between the master key and the ephemeral key. The IV is stretched to produce a stretched IV, which then combines with the master key through a key derivation function to generate the ephemeral key. This intermediary mechanism enables efficient master key reuse while ensuring dataset-level security isolation.
2Reliability
If unique keys are generated for each dataset, then security is improved, but storage efficiency and system complexity are worsened
Solution Approach 1:
The system extracts the unique identifier function from the key itself and places it in the initialization vector. The IV contains the unique dataset identifier and is stretched to produce the stretched IV, which then derives the ephemeral key. This extraction allows unique key generation without storing multiple full keys, reducing complexity.
Solution Approach 2:
The system performs preliminary action by stretching the IV before key derivation. The IV is stretched to produce a stretched IV with increased entropy and proper length for key derivation. This preliminary transformation ensures that even though we reuse the master key, each dataset receives a properly formed unique key material without requiring storage of multiple master keys.
3Reliability
If unique keys are stored for each dataset, then security is improved, but memory usage and operational efficiency are worsened
Solution Approach 1:
The system uses disposable ephemeral keys that are derived on-demand from the master key and IV, then discarded after use. These ephemeral keys are never stored in memory, eliminating the need to maintain multiple keys. The IV is stretched and used to derive the ephemeral key, which is then inaccessible after encryption, achieving security without memory burden.
Solution Approach 2:
The system changes the parameter of key persistence by transitioning from storing persistent unique keys to generating ephemeral keys that exist only during operation. The IV is stretched to produce stretched IV with specific length and entropy parameters suitable for key derivation, then the derived ephemeral key is used and discarded. This parameter change eliminates memory storage requirements while maintaining security.
Data Source
AI summary
Systems and methods for encrypting a dataset are provided. The methods may include deriving an ephemeral key, and encrypting the dataset using the ephemeral key to produce a ciphertext. The ephemeral key, without being saved after the encrypting, may be re-derivable on demand and operable to decrypt the ciphertext.