Facsimile Encryption Key Generation via Signal Values
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Solution Overview
Problem
Existing facsimile devices face challenges in maintaining confidentiality due to key leakage and inconsistency in encryption and decryption keys, leading to potential decryption by third parties and limited usable keys, which complicates secure cryptographic communications.
Innovation Solution
A facsimile device system with an operation part, storage part, transmission data generation part, encryption key generation part, and communication part that generates and transmits encrypted data using a common key and signal values, allowing for dynamic encryption key generation based on received signals and error detecting codes, ensuring secure communication even if the common key is leaked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common key is stored in both transmission-side and reception-side facsimile devices for encrypted communication, then encryption and decryption can be performed, but the key may be leaked to external parties allowing decryption by third parties
Solution Approach 1:
The encryption key is segmented into two parts: a common key stored in both devices and a dynamic key generated from transmission data. The complete encryption key is composed of both parts, so even if the common key is leaked, the dynamic portion from the transmitted data provides additional security layers that prevent successful decryption by third parties.
Solution Approach 2:
Transmission data serves as an intermediary element that bridges the common key and the final encryption key. The dynamic key is generated by processing transmission data through cryptographic functions, creating a mediator that transforms the static common key into a dynamic encryption key that changes with each transmission.
2Reliability
If complex encryption algorithms are adopted to prevent decryption even with leaked keys, then security is enhanced, but encryption and decryption throughput decreases requiring longer processing time
Solution Approach 1:
Instead of using overly complex encryption algorithms, the invention applies partial action by using simple XOR operations combined with dynamic key generation. This approach provides sufficient security through key dynamics rather than algorithmic complexity, maintaining high encryption throughput while achieving the security goal.
Solution Approach 2:
The invention changes the parameter of the encryption key itself rather than changing the encryption algorithm complexity. By dynamically generating keys based on transmission data, the system achieves enhanced security through parameter variation (key changes) rather than through complex algorithmic structures, thus maintaining high processing speed.
3Reliability
If a key table with multiple encryption keys is used to enhance confidentiality, then key leakage resistance is improved, but the number of usable keys is limited and trials for decryption become feasible
Solution Approach 1:
The invention transitions from a static key table to a dynamic key generation system. Instead of selecting from a limited set of pre-stored keys, the system dynamically generates encryption keys by processing transmission data through cryptographic functions. This creates an effectively infinite key space that adapts to each transmission, eliminating the limitations of fixed key tables.
Solution Approach 2:
The system changes the parameter of key generation from selection-based (choosing from a fixed table) to generation-based (creating new keys from transmission data). This parameter change transforms the key management approach, providing unlimited key availability while enhancing security against decryption trials.
4Ease of operation
If time information is used to determine keys from a key table, then key selection is automated, but inconsistency in time information between devices causes decryption failures
Solution Approach 1:
Transmission data serves as an intermediary that replaces time information for key generation. Instead of relying on device clocks that may differ, the system uses the transmitted data itself as the basis for generating the dynamic key, ensuring both transmission-side and reception-side devices generate identical keys without requiring synchronized time information.
Data Source
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AI summary
A facsimile device (1) includes: an operation part (11); a storage part (12) for storing therein the same common key as in a reception-side facsimile device (2); a transmission data generation part (15) for generating message data; an encryption key generation part (16) for generating an encryption key with use of a signal value of a cryptograph-generation applied signal, which is a signal selected from among signals transmitted to and received from the reception-side facsimile device (2); an encryption part (17) for generating encrypted data of the message data with use of the generated encryption key; and a communication part (13) for transmitting the encrypted data and decryption information including information as to the cryptograph-generation applied signal to the reception-side facsimile device (2).