Printing Device Command Conversion Security via Protocol Segmentation
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Solution Overview
Problem
Conventional printing devices lack security measures when receiving commands via communication interfaces, making them vulnerable to unauthorized processes and potential attacks.
Innovation Solution
Incorporating a controller with a memory and multiple communication interfaces, the printing device converts received PJL or PDL commands using stored conversion rules and executes processes based on these conversions, while prohibiting unauthorized rule-targeting processes received via insecure protocols, ensuring security by differentiating between secure and insecure communication protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the printing device receives commands via communication interfaces without security measures, then the device can operate freely and execute any command, but the device becomes vulnerable to unauthorized processes and malicious attacks
Solution Approach 1:
The patent segments command processing into two distinct paths: one for secure protocols (HTTPS, SFTP, SCP) and another for insecure protocols (HTTP, FTP, Samba). Each path has different execution permissions, with secure protocols allowing full command execution including rule-targeting commands, while insecure protocols prohibit rule-targeting commands. This segmentation resolves the contradiction by maintaining security without completely restricting legitimate command execution.
Solution Approach 2:
The patent applies different security policies to different communication protocols based on their inherent security characteristics. Secure protocols receive full command execution privileges, while insecure protocols receive restricted privileges that prohibit rule-targeting operations. This local quality approach allows the system to adapt security measures to the specific communication context, maintaining operational freedom for secure connections while protecting against vulnerabilities in insecure connections.
2Reliability
If the printing device prohibits rule-targeting commands from insecure protocols, then security is improved, but the device cannot execute legitimate commands that require rule modifications
Solution Approach 1:
The patent establishes security protocols and authentication mechanisms before command execution. By requiring secure protocols (HTTPS, SFTP, SCP) for rule-targeting operations, the system performs preliminary security verification to ensure the command source is authorized. This preliminary action prevents unauthorized modifications while allowing legitimate operations through properly authenticated channels, resolving the contradiction between security and operational capability.
Solution Approach 2:
The patent introduces protocol-type determination as an intermediary layer between command reception and execution. This intermediary evaluates the communication protocol type and directs commands to appropriate processing paths: secure protocols proceed to full execution, while insecure protocols are redirected to restricted processing that prohibits rule-targeting commands. This intermediary mechanism maintains ease of operation for legitimate commands while blocking potentially harmful operations.
3Adaptability or versatility
If the printing device converts all received PJL/PDL commands using stored conversion rules, then command compatibility is improved, but the device may execute malicious converted commands without detection
Solution Approach 1:
The patent segments command processing into conversion operations and execution operations with different security requirements. Command conversion is performed for all received commands to ensure compatibility, but execution is segmented based on protocol security characteristics. This allows the system to maintain command compatibility through universal conversion while protecting against malicious execution by restricting rule-targeting commands from insecure protocols.
Solution Approach 2:
The patent applies preliminary security verification through protocol-type determination before command execution. By identifying insecure protocols in advance and prohibiting rule-targeting command execution from these sources, the system performs preliminary anti-action against potential malicious commands. This prevents harmful factors from affecting the device while maintaining compatibility for legitimate commands through secure channels.
Data Source
AI summary
In a printing device, when: a memory stores a conversion rule for converting a pre-conversion PJL command to a post-conversion PJL command; and a PJL command corresponding to the pre-conversion PJL command is received, a controller performs a PJL command execution process to convert the received PJL command to the post-conversion PJL command according to the conversion rule and execute a process based on the post-conversion PJL command. On a condition that a rule-targeting command to execute a rule-targeting process targeting the conversion rule is received via a LAN interface according to a first protocol not ensuring a prescribed level of security, the controller prohibits execution of the rule-targeting process based on the rule-targeting command. On a condition that the rule-targeting command is received via an interface different from the LAN interface, the controller performs the rule-targeting process based on the rule-targeting command.