Plaintext Decomposition Encryption Without Explicit Initialization Vectors
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Solution Overview
Problem
Existing encryption methods for short messages in vehicle ecosystems face challenges in providing cryptographic integrity and confidentiality without increasing message length, particularly when using symmetrical encryption, and the use of initialization vectors is resource-intensive and synchronization issues arise.
Innovation Solution
A method that splits the plain text into two parts using a reversible decomposition function, encrypts each part separately with different encryption functions, and uses the encrypted parts as initialization vectors, eliminating the need for explicit initialization vectors while maintaining security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit initialization vectors are used for symmetrical encryption of short messages, then cryptographic security is improved, but message length increases and synchronization issues arise
Solution Approach 1:
The patent extracts the initialization vector function from being a separate explicit parameter and integrates it into the encryption process itself. The first cipher text block serves as the initialization vector for subsequent blocks, eliminating the need for separate IV transmission and reducing message overhead.
Solution Approach 2:
The patent merges the initialization vector with the first cipher text block. Instead of transmitting IV and cipher text separately, the first block performs dual function as both initialization vector and encrypted data, combining two previously separate elements into one.
2Reliability
If explicit initialization vectors are transmitted with each message, then encryption security is maintained, but transmission resources are consumed and synchronization problems occur
Solution Approach 1:
The encryption system serves itself by using the first cipher text block as the initialization vector for subsequent blocks. This self-referential approach eliminates the need for external IV transmission, making the system self-sufficient and reducing resource consumption.
Solution Approach 2:
The first cipher text block serves multiple functions: it is both the encrypted data for the first plain text block and the initialization vector for encrypting subsequent blocks. This multi-functionality reduces the overall quantity of data that needs to be transmitted.
3Reliability
If separate encryption functions are used for each plain text block, then encryption security is improved, but device complexity increases
Solution Approach 1:
The patent segments the encryption process into distinct stages: first block encryption using a key derivation function, and subsequent block encryption using the previous cipher text block as IV. This segmentation allows each stage to use optimized, simpler functions while maintaining overall security.
Data Source
AI summary
Plain text that is part of the plain text message is encrypted using a reversible decomposition function, which allocates two plain text parts to each plain text to be encrypted. These plain text parts are then encrypted with at least one encryption function in two separate steps. Since the decomposition function is reversible, the inverse function can always be used to unambiguously derive the original plain text from the plain text parts. This is now used to decrypt the cipher text message created by the encryption with the cipher text parts using a suitable decryption. The cipher text parts are decrypted one after the other using at least one decryption function to then recover the plain text. A conventional initialization vector for encryption and decryption is then replaced by selected or all bits of the second plain text part or a bit sequence derived from this.