Skip to main content

Extract Signature Data From PDF (JavaScript)

Use this guide to produce the two values required by POST /v1/signature/verify:

  • Document hash as uppercase hex (hash)
  • PKCS7 signature as Base64 (signature)

The extractor supports PDFs with one or more signatures and returns one { signature, hash } pair per detected signature object.

Prerequisites​

  • Signed PDF file available as bytes (Uint8Array)
  • JavaScript runtime that supports ES modules

1. Add the extractor helper​

Download and include:

2. Extract verification inputs​

import { readFile } from "node:fs/promises";
import { SignatureExtractor } from "./SignatureExtractor.js";

const pdfPath = "./sample-signed.pdf";
const pdfBytes = new Uint8Array(await readFile(pdfPath));

const extractor = new SignatureExtractor(pdfBytes);
const entries = extractor.extract();

for (const [index, entry] of entries.entries()) {
  console.log(`Signature ${index + 1}`);
  console.log("hash:", entry.hash);
  console.log("signature:", entry.signature);
}

Output shape:

[
  {
    "hash": "A1B2...",
    "signature": "MII...="
  }
]

3. Validate output format​

Before calling the API, verify:

  • hash contains only hex characters and is uppercase
  • signature is Base64 encoded
  • At least one entry was extracted from the signed PDF

4. Submit to Document Validator​

Use each { hash, signature } pair as an item in your request body:

Limitations​

This helper is intentionally minimal and does not implement full PDF parsing. It is designed to extract signature data for verification workflows and assumes standard PDF signature object structures.