Proxy Re-Encryption for Secure Network Printing
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Solution Overview
Problem
Network printing systems face security challenges due to untrusted servers and printers, particularly in publicly accessible services, where communication between the server and printer may not be secure, and users may not know which printer to select in advance to ensure secure printing.
Innovation Solution
The implementation of proxy re-encryption (PRE) in network printing systems allows users to securely print jobs by encrypting them with the public key of a chosen printer, delegating decryption rights to a semi-trusted print server without revealing private keys, enabling secure translation of ciphertexts to the selected printer's public key for decryption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user encrypts the print job with the public key of the selected printer before sending to the print server, then the confidentiality of the print job is improved, but the user must know which printer to use in advance, reducing flexibility
Solution Approach 1:
The user device performs preliminary encryption of the print job with the user's own public key before uploading to the print server. This preliminary action ensures confidentiality is established in advance, while the actual printer-specific encryption is deferred until later when the printer is selected, thus resolving the contradiction between early encryption for security and late selection for flexibility
Solution Approach 2:
The print server acts as an intermediary that receives the initially encrypted print job and facilitates the subsequent re-encryption process. The server mediates between the user's initial encryption and the final printer-specific encryption, enabling the two-stage process that resolves the contradiction between confidentiality and flexibility
2Ease of operation
If the print server has access to the plaintext print job for processing, then the ease of operation is improved, but the security against untrusted servers deteriorates
Solution Approach 1:
The system performs preliminary encryption of the print job with the user's public key before submission to the print server. This preliminary security measure ensures that even if the server is untrusted, it cannot access the plaintext content, while still allowing the server to perform its processing functions on the encrypted data
Solution Approach 2:
The encryption state of the print job changes from plaintext to ciphertext during transmission to and storage on the print server. This parameter change in the data state maintains security while allowing the server to perform operations on the encrypted form, resolving the contradiction between security and processing capability
3Reliability
If the system uses traditional encryption requiring pre-selection of printer, then the security is improved, but the device complexity increases due to key management requirements
Solution Approach 1:
The proxy re-encryption mechanism acts as an intermediary that simplifies key management. Instead of requiring the user device to directly manage and distribute multiple printer public keys, the system uses a standardized proxy re-encryption protocol that handles the key translation automatically, reducing the complexity burden while maintaining security
Solution Approach 2:
The proxy re-encryption mechanism provides a universal solution that works across multiple printers and users through a standardized protocol. This multi-functional approach eliminates the need for custom key management solutions for each printer-user pair, reducing overall system complexity while maintaining strong security guarantees
Data Source
AI summary
A network printing system comprising a user device to encrypt a print job using a public key of a user and to transmit the encrypted print job to a print server. The system may further comprise the print server to re-encrypt the encrypted print job using the re-encryption key. The system may further comprise the printer to decrypt the re-encrypted print job using a private key of the printer and print the decrypted print job.