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Orilami

Upload a signed PDF to audit its signatures, revisions and layer integrity. The verdict, signer identities, PAdES tiers and any tamper flags appear here.

PDF Signature Forensics & Document Layer Integrity Analyzer

A byte-level forensic engine for digitally signed PDFs. It parses the raw file buffer — not a viewer's rendered model — to verify what each signature actually covers, decode the CMS/PKCS#7 cryptography, walk the incremental-update revision chain, and detect shadow attacks and in-place visual overlays. Everything runs in a Web Worker in your browser; the file never leaves your device and no CA, OCSP or timestamp server is ever contacted.

What it verifies

  • ByteRange integrity: the [o1 l1 o2 l2] window is checked against the file — it must start at byte 0 and leave a gap only for /Contents. Secondary ByteRange/Contents injections and trailing unsigned data are flagged.
  • CMS / PKCS#7: the DER SignerInfo is decoded and the signature math verified with WebCrypto — RSASSA-PKCS1-v1_5, RSA-PSS and ECDSA over SHA-256/384/512 — against the exact signed bytes.
  • Certificates & PAdES tier: the certificate chain, key usage and validity windows are surfaced, and the PAdES profile (B-B / B-T / B-LT / B-LTA) is classified from embedded timestamps and the DSS.
  • Incremental updates: every %%EOF revision is diffed to separate permitted additions (a later signature, a DSS) from suspicious mutations that redefine signed objects.
  • Shadow attacks: Hide, Replace and Hide-and-Replace vectors — a swapped Catalog or Pages tree, mutated AcroForm/XFA, redefined fonts, or an opaque content-stream overlay drawn over signed content.

On trust anchors and revocation

Because this tool is strictly local, it does not validate certificates against AATL / eIDAS trust lists or perform live OCSP/CRL revocation checks — both would require network calls and shipping large trust stores. Embedded revocation material (DSS/VRI) and timestamp tokens are decoded and shown, but reported as not validated. For legal non-repudiation sign-off, confirm trust-anchor and revocation status in a validator with network access.

FAQ

Is my PDF uploaded anywhere?
No. Parsing, hashing and signature verification all run in a Web Worker in your browser. The file never leaves your device and no external server is contacted.
What does “modified after signing” mean?
The signatures verify cryptographically, but a later incremental-update revision changed protected structure (e.g. the Catalog, a page, a form field, or added an opaque overlay) in a way that affects what the document shows — the classic shadow-attack pattern.
Why isn’t the certificate marked trusted?
Trust-anchor validation against AATL/eIDAS and OCSP/CRL revocation require network access and bundled trust stores, which would break the local-only privacy model. The chain is decoded and shown, but trust and revocation are reported as not validated.
Which signature algorithms are verified?
RSASSA-PKCS1-v1_5, RSA-PSS and ECDSA over SHA-256/384/512, via the platform WebCrypto. Legacy adbe.x509.rsa.sha1 (bare PKCS#1) signatures are decoded but not cryptographically verified.
Can it export a report?
Yes — the full JSON forensic report (verdict, per-signature crypto result, certificate chain, timestamps, revision chain and every tamper finding with severity) downloads with one click.