Transparent Serial Encryption via Opportunistic Sync
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Solution Overview
Problem
Existing encryption methods for serial data streams, particularly in legacy and RF communication systems, face challenges due to the overhead introduced by framing and cryptographic synchronization data, which can degrade RF link performance and introduce errors, making it difficult to implement modern block ciphering effectively.
Innovation Solution
The use of block cipher techniques to encrypt and decrypt serial data streams with opportunistic insertion of framed cryptographic synchronization messages during idle periods, maintaining relative timing and minimizing overhead, allowing for transparent encryption/decryption without additional framing, using a block cipher like AES in counter mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block cipher techniques are used to encrypt serial data streams, then encryption security is improved, but overhead from framing and cryptographic synchronization data degrades RF link performance
Solution Approach 1:
The patent combines the framing of cryptographic synchronization data with the existing serial data stream protocol structure. The synchronization data is framed using the same escape sequence mechanism already present in the serial communication protocol, merging two functions (data framing and synchronization) into a single integrated approach that eliminates separate overhead structures.
Solution Approach 2:
The patent implements opportunistic insertion of cryptographic synchronization data, sending synchronization frames only when idle periods occur in the data stream rather than continuously. This partial action approach reduces the total amount of synchronization overhead transmitted while still maintaining adequate synchronization for security operations.
2Reliability
If cryptographic synchronization data is inserted into the serial data stream, then encryption/decryption synchronization is improved, but error propagation in noisy RF conditions worsens
Solution Approach 1:
The patent uses escape sequences as preliminary markers to indicate the start of cryptographic synchronization data frames before the actual synchronization data is transmitted. This preliminary action allows the receiving system to prepare for and correctly interpret the upcoming synchronization data, reducing errors from misinterpretation of the frame structure in noisy conditions.
Solution Approach 2:
The patent includes authentication data in the cryptographic synchronization frames that provides feedback verification. The receiving system can verify the authenticity and integrity of received synchronization data, detecting and correcting errors before they propagate through the decryption process.
3Reliability
If modern block ciphering is implemented in serial communication systems, then cryptographic security is improved, but device complexity increases
Solution Approach 1:
The patent designs the cryptographic device to handle multiple functions using a unified architecture: it processes both user data and cryptographic synchronization data through the same encryption/decryption engine, uses the same escape sequence mechanism for framing, and maintains synchronization counters that serve both security and protocol functions. This multi-functionality reduces overall device complexity despite implementing modern block ciphering.
Data Source
AI summary
Disclosed herein are methods and systems for configuring and using one or more block ciphering techniques in order to encrypt/decrypt serial data streams while maintaining cryptographic synchronization and attempting to minimize the amount of overhead introduced into the stream. The techniques disclosed herein may be used to encrypt and decrypt serial data streams using a block cipher in a manner that can be substantially transparent to the devices involved in the serial communication session. For example, the serial user data may be left unframed by the encryption device while monitoring for opportunistic times to transmit framed cryptographic synchronization information during periods of relative inactivity in an asynchronous serial data stream. A cryptographic device implementing the techniques described herein may be configured to implement one or more of an encryption device or a decryption device.