Overview - ISO/TS 32002:2022 (PDF 2.0) and digital signatures
ISO/TS 32002:2022 extends ISO 32000-2 (PDF 2.0) to modernize digital signature support in PDF documents. The Technical Specification adds support for additional elliptic-curve algorithms and specifies how PDF documents declare these extensions. It is focused on cryptographic signature formats and algorithm interoperability; it does not prescribe document conversion processes, rendering/UI details, storage media, conformance test methods, or required hardware/OS.
Keywords: ISO/TS 32002:2022, PDF 2.0, digital signatures, elliptic curve, EdDSA, ECDSA, Ed25519, Ed448, Brainpool, NIST P-curve.
Key topics and technical requirements
- Extension schema: PDFs using these enhancements must include an Extensions dictionary in the document catalog with a prefix name ISO_. The developer extensions dictionary entries include:
- Elliptic-curve signature support:
- Adds support for NIST P-curves (P-256, P-384, P-521), Brainpool curves (brainpoolP256r1, brainpoolP384r1, brainpoolP512r1), and Edwards-curve EdDSA (Ed25519, Ed448).
- Digest algorithm mapping (selected examples from the specification):
- P-256 → SHA‑256, SHA3‑256
- P-384 → SHA‑384, SHA3‑384
- P-521 → SHA‑512, SHA3‑512
- brainpoolP256r1 → SHA‑256 / SHA3‑256 (also supports SHA‑384, SHA‑512 variants)
- Ed25519 → SHA‑512
- Ed448 → SHAKE256 (id-shake256)
- Algorithm and certificate requirements:
- Certificates for ECDSA keys must use namedCurve ECParameters (no implicit or specifiedCurve).
- ECDSA signatures are represented using DER-encoded ECDSA-Sig-Value as per RFC 5753.
- If signedAttrs is present in SignerInfo, the same message-digest algorithm must be used for both the signedAttrs digest and the encapsulated content digest.
- Implementation guidance:
- PDF processors may ignore or handle documents signed with curves not in the supported lists; unnamed custom curves are discouraged.
Applications - who uses this standard
- PDF software developers (renderers, signing libraries) implementing PDF 2.0 digital signature features.
- E-signature and PKI providers updating signing tools to support EdDSA and newer ECDSA curves.
- Security architects and compliance teams specifying cryptographic requirements for signed PDFs.
- Certificate authorities and integrators ensuring certificates and CMS structures comply with RFCs referenced by ISO/TS 32002:2022.
Related standards and references
- ISO 32000-2:2020 (PDF 2.0)
- ISO/TS 32001 (hash algorithm extensions)
- IETF RFCs: 5480, 5753, 8032 (EdDSA), 8419, 5639, 6932
- FIPS PUB 202 (SHA-3) and BSI TR-03111 (Brainpool guidance)
This specification helps keep PDF 2.0 digital signatures current with modern cryptography, enabling secure, interoperable signed documents using NIST P-curves, Brainpool, and Ed25519/Ed448 EdDSA algorithms.