Font File Watermarking for Unauthorized Link Prevention
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Solution Overview
Problem
The challenge is to prevent unauthorized font linking using the @font-face command in CSS, particularly in scenarios where license restrictions limit access to linkable fonts, and to track unauthorized use or copying of fonts.
Innovation Solution
Embedding watermarks in font files, including one or more points in glyphs and tables, to validate requests and track font usage, allowing authorized access while monitoring for improper use or copying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the @font-face command is used to link to fonts stored online, then font availability and display consistency are improved, but unauthorized access and copyright infringement risks increase
Solution Approach 1:
The patent applies preliminary action by embedding watermarks in font files before they are served to users. The watermark is embedded in the font data structure (specifically in the glyf table) before the font is transmitted through the @font-face mechanism. This pre-embedding ensures that if the font is unauthorizedly used or copied, the watermark will be present to identify and trace the source of infringement, thus preventing unauthorized access while maintaining font availability.
Solution Approach 2:
The watermark serves as an intermediary element within the font file structure. It is embedded in the glyf table of the font file and acts as a hidden identifier that does not affect the visual rendering of the font but enables tracking and authorization verification. This intermediary mechanism allows the system to maintain normal font functionality while adding a layer of protection against unauthorized access.
2Ease of operation
If font files are served without watermarks, then ease of access and implementation are improved, but tracking and detecting unauthorized copying becomes difficult
Solution Approach 1:
The patent uses copying by embedding a watermark copy within the font file structure. The watermark is a duplicate or replicated identifier that is embedded in the glyf table of the font file. This copied element serves as a traceable marker that travels with the font file wherever it is distributed, enabling detection of unauthorized copying while maintaining the original font functionality and ease of access.
3Reliability
If watermarks are embedded in font files, then font protection and authorization tracking are improved, but font file complexity and processing requirements increase
Solution Approach 1:
The patent applies local quality by embedding the watermark in a specific localized area of the font file structure - specifically in the glyf table which stores glyph outline data. The watermark is embedded at specific offsets within this table (e.g., at offset 0x0000 or at specific glyph record locations) without affecting other parts of the font file. This localized embedding adds protection while minimizing impact on overall font file structure and processing.
Solution Approach 2:
The watermark is implemented as a lightweight, minimal-data structure embedded in the font file. It uses simple numerical identifiers and offset values rather than complex protective mechanisms. The watermark adds minimal processing overhead and does not require sophisticated verification systems, making it a cost-effective solution that can be implemented without significantly increasing device or system complexity.
Data Source
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AI summary
Methods, computer readable media, and apparatuses for preventing unauthorized font linking are presented. A request for a font file may be received. It may be determined whether the request is valid, and this determination may be based on a security token and/or a referrer string. If the request is determined to be valid, a first watermark may be embedded in the font file, and the first watermark may be based on the security token. The first watermark may include at least one point in at least one glyph contained in the font file. A second watermark may be embedded in the font file, and the second watermark may include at least one table that identifies a customer. The font file then may be served to the requestor.