AES Key Generator Segmentation for On-the-Fly Changes
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Solution Overview
Problem
Existing AES hardware implementations sacrifice key security and flexibility for high throughput, as they bond the expanded key generator and AES algorithm block cipher, making it difficult to change keys on the fly and leaving the cipher key vulnerable to theft.
Innovation Solution
The circuit architecture separates the expanded key generator and AES algorithm block cipher, allowing asynchronous operation, generating and storing sub-keys in RAM for immediate retrieval, enabling fast key changes and detaching the input cipher key from the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the expanded key generator and AES algorithm block cipher are bonded together to achieve high throughput, then the encryption/decryption rate is improved, but the key security and flexibility deteriorate because the cipher key must remain attached to the system and is vulnerable to theft
Solution Approach 1:
The patent divides the cryptographic system into two independent modules: an expanded key generator and an AES algorithm block cipher. This segmentation allows the key generator to be detached from the cipher system after generating expanded keys, which are then stored in internal RAM. The separation enables high throughput operation while improving key security, as the original cipher key no longer needs to remain attached to the system.
Solution Approach 2:
The patent extracts the expanded key generator from the AES block cipher system. The generator produces the necessary expanded keys and transfers them to the cipher module's internal memory, then detaches completely. This extraction eliminates the security vulnerability of having the cipher key permanently attached to the system while maintaining the ability to provide keys at high rates.
2Speed
If the expanded key generator and AES algorithm block cipher operate synchronously for high performance, then the processing speed is improved, but the key changing flexibility deteriorates because the key cannot be changed on the fly
Solution Approach 1:
The patent implements dynamic key changing capability by allowing the expanded key generator to operate independently and update the cipher system's internal RAM with new expanded keys at any time. The generator can produce a new set of expanded keys for each unique cipher key input, enabling on-the-fly key changes without disrupting the synchronous operation of the AES block cipher. This dynamic approach maintains high processing speed while providing flexible key management.
3Duration of action of stationary object
If the cipher key is kept attached to the system for continuous operation, then the encryption continuity is improved, but the vulnerability to key theft increases
Solution Approach 1:
The patent applies preliminary action by having the expanded key generator produce and transfer all necessary expanded keys to the AES block cipher's internal RAM before the cipher operation begins. The generator then detaches, and the cipher system operates autonomously using the pre-loaded keys from internal memory. This preliminary key preparation ensures continuous encryption operation while eliminating the need for the external cipher key to remain attached, thereby preventing key theft.
Data Source
AI summary
A fast key-changing hardware apparatus, which generates one sub-key each clock cycle, which is used by advanced encryption system (AES) algorithm block cipher, is independent from the AES algorithm block cipher. The invented apparatus automatically generate expanded keys from the input cipher key, store them in the key expanded RAM and ready to be used by the AES algorithm block cipher. If the key changing and the key expanding speed in the fast key-changing device is as fast as the data block (i.e. 128, 192, or 256 bits) processing speed in the AES algorithm block cipher, the cipher system has the characteristic of one-time pad perfect cryptography. When using this device with a fixed key cipher system, the original input cipher key can be detached or destroyed from the system and guarantees the safety of the cipher key.