Standards Conformance
SimpleSign implements PAdES, CAdES, and XAdES digital signatures with conformance boundaries documented below. This document details compliance with ISO, ETSI, RFC, and Brazilian (ICP-Brasil) specifications.
ISO 32000-1:2008 Compliance
SimpleSign implements PDF digital signatures in strict conformance with ISO 32000-1. Compliance is verified by 46 automated unit tests, each mapping to a specific section of the standard:
| ISO Section | Requirement | Tests |
|---|---|---|
| §7.3.4.2 | String escaping (\n, \r, \t, \b, \f, \\, \(, \)) |
2 |
| §7.5.4–6 | Incremental updates (original bytes, /Prev chain, /Size, startxref, %%EOF) |
5 |
| §7.5.4 | Xref table entries exactly 20 bytes (oooooooooo ggggg n\r\n) |
1 |
| §7.5.8 | Cross-reference streams (/Type /XRef, /W, /Index, self-entry, /FlateDecode) |
7 |
| §7.9.4 | Date format D:YYYYMMDDHHmmss+HH'mm' (not Z suffix) |
1 |
| §8.6.5 | Widget annotation flags (/F 132 visible, /F 0 invisible) |
2 |
| §8.7 | Page /Annots array updated with field reference |
1 |
| §12.7 | AcroForm (/Fields, /SigFlags 3, no /Type, preserves /DR, /DA, /Q) |
4 |
| §12.7.4.5 | Signature fields (/FT /Sig, /V, /T, /P, unique names) |
5 |
| §12.8.1 | Signature dictionary (/Type /Sig, /Filter, /SubFilter, /ByteRange, /Contents) |
7 |
| §12.8.2 | DocMDP certification (/Reference, /TransformMethod, /P, /Perms) |
4 |
| §12.8.3 | Appearance stream (/AP /N, /Subtype /Form, /BBox) |
2 |
| Cross-cutting | Every object has matching endobj, BuildXrefStream correctness |
5 |
ISO 32000-2:2020 (PDF 2.0) Compliance
SimpleSign is designed with PDF 2.0 alignment in mind. The digital signature subsystem covers the key requirements introduced or formalized in ISO 32000-2:
| Feature | 32000-2 Requirement | Status | Notes |
|---|---|---|---|
| SubFilter | ETSI.CAdES.detached as default |
✅ | adbe.pkcs7.detached remains available while retaining PAdES attributes |
| Cross-reference streams | Xref streams required (classic deprecated) | ✅ | Full support: /Type /XRef, /W, /Index, ObjStm, FlateDecode, PNG predictors |
| Hash algorithms | SHA-256/384/512 required; MD5 deprecated | ✅ | SHA-256 default; MD5 rejected at signing time |
| DSS dictionary | Formalized in §12.8.4.3 | ✅ | CRLs, OCSPs, Certs extraction and embedding |
| VRI structure | Formalized in §12.8.4.4 | ✅ | Keys validated, /TU timestamps, per-signature entries |
| DocMDP certification | Enhanced in §12.8.2 | ✅ | Permission levels 1/2/3, /Perms, /TransformMethod |
| PAdES alignment | Aligns with ETSI EN 319 142 | ✅ | B-B, B-T, B-LT, B-LTA fully implemented |
| RC4 encryption | Removed | ✅ | Encrypted PDFs refused entirely |
| AES-256 encryption | Required for encrypted PDFs | N/A | Encrypted PDFs out of scope (decrypt first) |
| PDF 2.0 header | %PDF-2.0 |
✅ | Detected, parsed, reported in inspection |
| SHA-1 | Deprecated for new signatures | ✅ | Rejected for signing; flagged as deprecated in inspection/validation |
Design philosophy: SimpleSign refuses unsafe operations (RC4, MD5, encrypted PDFs) rather than implementing them insecurely. Encryption is intentionally out of scope — use qpdf or Adobe Acrobat to decrypt before signing.
Conformance Matrix
| Standard | Levels | Status | Notes |
|---|---|---|---|
| ISO 32000-1:2008 | Signature subsystem | ✅ | 46 unit tests per section (see above) |
| ISO 32000-2:2020 | Signature subsystem | ✅ | XRef streams, CAdES, DSS, VRI, DocMDP, SHA-1 deprecation, PDF 2.0 detection |
| PAdES (ETSI EN 319 142) | B-B (Basic) | ✅ | CMS + signingCertificateV2 |
| B-T (Timestamp) | ✅ | RFC 3161 timestamp token | |
| B-LT (Long-Term) | ✅ | DSS dictionary with CRL/OCSP | |
| B-LTA (Archive) | ✅ | Document timestamp for decade-long validity | |
| DocMDP (Certification) | ✅ | Three permission levels (P=1, 2, 3) | |
| PDF/A preservation | ✅ | Detects and preserves 1a/1b/2a/2b/2u/3a/3b/3u/4a/4b/4u/4e | |
| DOC-ICP-15 | AD-RB (Referência Básica) | ✅ | CMS + signingCertificateV2, ICP-Brasil chain |
| AD-RT (Referência Temporal) | ✅ | AD-RB + RFC 3161 timestamp | |
| AD-RV/AD-RC/AD-RA | ✅ | CAdES-XL/A: certificate-refs, revocation-refs, cert-values, revocation-values via CmsAttribute | |
| RFC 5652 | CMS SignedData | ✅ | Full compliance (§5.1–5.6), detached signatures |
| ETSI EN 319 142-1 | PAdES core (B-B, B-T, B-LT, B-LTA) | ✅ | Signature creation & augmentation |
| ETSI EN 319 142-2 | PAdES extended (LTV, archival) | ✅ | DSS/VRI + document timestamps |
| ETSI EN 319 122-1 | CAdES B-B, B-T, B-LT, B-LTA | ✅ | RFC 3161 binding, per-path LTV evidence, archiveTimestampV3 + ATSHashIndexV3 |
| ETSI EN 319 132-1 | XAdES B-B, B-T, B-LT, B-LTA | ✅ | ETSI archive preimage; XMLDSig reference processing; same-document distributed unsigned properties and counter-signatures |
| RFC 8702 | SHA-3 OIDs in CMS | ✅ | id-sha3-256/384/512, id-rsassa-pkcs1-v1_5-with-sha3-256/384/512, id-ecdsa-with-sha3-256/384/512 |
| RFC 8933 | EdDSA in CMS | ⏳ | OIDs are recognized, but signing is deferred until raw external output is verifiable on every target |
| RFC 8032 | EdDSA algorithm | ⏳ | Ed25519/Ed448 signing is not advertised in v0.9.0 |
| RFC 8410 | EdDSA X.509 identifiers | ✅ | OIDs 1.3.101.112 (Ed25519) / 1.3.101.113 (Ed448) |
SubFilter Support
| SubFilter | Sign | Inspect | Validate | Notes |
|---|---|---|---|---|
ETSI.CAdES.detached |
✅ (default) | ✅ | ✅ | Modern ETSI standard |
adbe.pkcs7.detached |
✅ | ✅ | ✅ | Compatibility subfilter with PAdES attributes |
ETSI.RFC3161 |
✅ | ✅ | ✅ | Document timestamps (B-LTA) |
Supported Algorithms
| Category | Algorithms |
|---|---|
| Hash | SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-384, SHA3-512 |
| Signature | RSA PKCS#1 v1.5, RSA-PSS, RSA-SHA3-256/384/512¹, ECDSA (P-256/P-384/P-521), ECDSA-SHA3-256/384/512¹ |
| Revocation | CRL, OCSP, embedded DSS |
| Timestamps | RFC 3161 |
| PDF/A | 1a, 1b, 2a, 2b, 2u, 3a, 3b, 3u, 4a, 4b, 4u, 4e (detection + preservation) |
¹ SHA-3 signature and digest OIDs defined in RFC 8702; CMS encoding defined in RFC 8933. ² EdDSA algorithm identifiers remain recognized, but v0.9.0 rejects EdDSA signing rather than producing external output that net8.0 cannot verify.
CAdES and XAdES archival boundaries
For B-T, B-LT, and B-LTA, SimpleSign binds every RFC 3161 response to the request
before embedding it and derives the reported level from final-artifact inspection.
CAdES archive timestamps use ATSHashIndexV3; XAdES builds the ETSI archive
preimage from XMLDSig references, SignedInfo, SignatureValue, optional KeyInfo,
unsigned qualifying properties, and applicable ds:Object values.
XAdES accepts base64, enveloped-signature, the standard signature-exclusion XPath,
and C14N/exclusive-C14N transforms for archive-reference processing. Distributed
ArchiveTimeStamp properties are supported when every Include is a same-document
bare-name ID reference; their declared order is preserved and comments are excluded
before canonicalization. XSLT, network/external Include resources, unsupported
transforms, and an archive operation without an explicit target in a multi-signature
document fail closed rather than producing an archival-level claim.
Use XadesSignatureValidator.ValidateAll(...) for a document that contains multiple
XMLDSig signatures. Validate(...) intentionally returns an invalid structured result
for that ambiguous case instead of inspecting only the first signature.