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Digital proof

Local PDF anti-tamper signature proof

Generate an ECDSA proof for exact PDF bytes, export a JSON proof, or embed a portable PDFPerch proof marker for demo verification.

Important: this is a real Web Crypto anti-tamper proof, but it is not an Adobe/PAdES legal signature. PAdES requires CMS/PKCS#7, certificates, ByteRange placeholders and usually trusted timestamps.
Private keys are generated locally and never uploaded.

User guide

How to use Digital Proof Demo

Create a browser key pair, sign a defined byte payload, and verify the detached proof locally.

  1. 1

    Upload a PDF and generate or import a local signing key.

  2. 2

    Create the defined canonical payload and SHA-256 digest.

  3. 3

    Sign it with Web Crypto and export the proof package.

  4. 4

    Re-import the package and verify the signature and digest.

Best for

  • Tamper-evidence demonstrations
  • Learning browser cryptographic signing

Important limitation

A custom proof embedded as metadata is not an Adobe-compatible PDF signature and is not automatically legally compliant. Standard PDF signatures require ByteRange, CMS, certificates, trust, and long-term validation.

Frequently asked questions

Is this PAdES?

No. Use a standards-compliant signing provider for PAdES.

Why not hash the final file after embedding?

Embedding changes the bytes; standard PDF signatures solve this with a reserved signature range.

PDFPerch processes files locally unless this guide explicitly identifies a cloud-dependent feature. Always keep an original copy and verify critical output before submission, printing, signing, or accounting use.