PDF Custom Fields for Secure Mixed Content Storage
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Solution Overview
Problem
Existing digital file formats, such as PDF, face challenges in securely storing and managing a mix of confidential and non-confidential content while maintaining compatibility across various systems and platforms, as they often rely on password protection or symmetric algorithms that are vulnerable to key search techniques and cannot prevent or detect document manipulation during transmission.
Innovation Solution
A system that assembles a portable document format (PDF) file with encrypted and unencrypted content using custom fields, encrypting metadata and content maps with unique keys, and includes alternative content for display in case of authentication failures, ensuring increased security and compatibility without relying on user private keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If password protection or symmetric algorithms are used to secure PDF files, then basic security is provided, but the files remain vulnerable to key search techniques and document manipulation
Solution Approach 1:
The patent segments the PDF file into distinct components: unencrypted content, encrypted content with unique encryption keys, metadata, and content maps. This segmentation allows different security levels to be applied to different parts of the document, preventing uniform vulnerability to key search attacks while maintaining overall security.
Solution Approach 2:
The patent implements local quality by applying encryption selectively to specific content portions rather than the entire document. Each encrypted portion uses its own unique key, allowing the system to protect only the confidential portions while leaving non-confidential content accessible, thereby reducing the attack surface for key search techniques.
2Reliability
If encryption is applied to the entire PDF file, then security is improved, but file size increases and computational demands increase
Solution Approach 1:
The patent divides the PDF into encrypted and unencrypted segments, applying encryption only to confidential content. This reduces the total amount of data that needs to be encrypted and stored, thereby minimizing file size increase while maintaining security for sensitive portions.
Solution Approach 2:
The patent applies partial encryption rather than full encryption, encrypting only the portions of content that require protection. This partial action reduces computational demands and file size overhead while providing adequate security for confidential information.
3Reliability
If encryption is applied to the entire PDF file, then security is improved, but computational demands increase
Solution Approach 1:
The patent segments content into encrypted and unencrypted portions, requiring computational resources only for the encrypted segments during processing. This reduces the overall computational burden compared to encrypting and processing the entire document, while maintaining security for sensitive content.
Solution Approach 2:
The patent performs partial encryption on only the confidential portions of the document, reducing the computational effort required for both encryption and decryption operations compared to full-file encryption, while still providing necessary security protection.
4Reliability
If custom fields with unique encryption keys are used, then security against manipulation is improved, but device complexity increases
Solution Approach 1:
The patent introduces content maps as intermediary structures that track encrypted content portions and their associated unique keys. These content maps serve as mediators between the encrypted content and the decryption process, providing security against manipulation while organizing the complexity in a manageable way.
Solution Approach 2:
The patent performs preliminary organization of encrypted content into structured custom fields with associated metadata and content maps before final assembly. This preliminary action establishes security structures and key associations in advance, reducing the complexity of the decryption and verification process.
5Quantity of substance
If selective encryption of content portions is implemented, then file size is reduced, but compatibility with existing PDF programs may be compromised
Solution Approach 1:
The patent implements a universal PDF structure that combines encrypted and unencrypted content within a single document format. The encrypted portions use standard PDF encryption mechanisms that existing PDF programs can recognize, while unencrypted portions remain fully accessible, providing broad compatibility across different PDF readers and editors.
Solution Approach 2:
The patent segments the PDF into compatible encrypted and unencrypted sections using standard PDF structure conventions. This segmentation allows existing PDF programs to handle the document according to their capabilities, with compatible programs able to process encrypted portions while simpler programs can access unencrypted content, maintaining wide compatibility.
Data Source
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AI summary
Examples include assembly of a portable document format file including encrypted content, unencrypted content, and/or alternative content. In an example, metadata, data block(s), and a content map are signed and stored in, or assembled into, a custom field or fields of the portable document format file. The metadata, data block(s), and content map are encrypted and assembled into a custom field or fields of the portable document format file with an encrypted key or keys. Unencrypted and/or alternative content may also be stored in the assembled portable document format file.