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  3. GetVerifiedSignatures "Not Recognised" Exception

GetVerifiedSignatures "Not Recognised" Exception

Curtis Chau
Curtis Chau
Updated:

On .NET 4.8, GetVerifiedSignatures fails on some digitally signed PDFs, throwing an unhandled exception instead of returning a validation result.

Signer 1.2.840.10045.4.3.2WITHRSA not recognised

The signature algorithm OID 1.2.840.10045.4.3.2 appears in some signed PDFs, and versions up to 2026.4.1 have no handler for it. Rather than returning a result, GetVerifiedSignatures throws when it hits this OID, so validation cannot complete.

Solution

Upgrade IronPDF to version 2026.6 or later. Support for the 1.2.840.10045.4.3.2 algorithm was added in that release, and GetVerifiedSignatures returns a normal validation result once you are on it.

Curtis Chau
Curtis Chau
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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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