EncDotNet.S100.ExchangeSets 0.9.0

EncDotNet.S100.ExchangeSets

Reader for S-100 Exchange Set catalogues, dataset/support file discovery, and digital signature verification.

Overview

This library parses S-100 Exchange Set CATALOG.XML files and provides access to the datasets and support files within an exchange set. Key types include:

• ExchangeSet — opens and navigates an exchange set through an IAssetSource.
• ExchangeCatalogue — the parsed catalogue metadata.
• ExchangeCatalogueReader — XML parser for the exchange catalogue.
• DatasetDiscoveryMetadata — metadata for each dataset in the exchange set (file name, bounding box, product specification).
• SupportFileDiscoveryMetadata — metadata for support files.
• CatalogueDiscoveryMetadata — metadata for embedded catalogues.

Digital Signature Verification

The library implements the S-100 Part 15 Data Protection Scheme for signature verification. Exchange sets may include per-file digital signatures (DSA or ECDSA P-256 over SHA-256) embedded in CATALOG.XML, along with a certificate block referencing the signing data provider.

Model types

These are surfaced as properties on DatasetDiscoveryMetadata, SupportFileDiscoveryMetadata, CatalogueDiscoveryMetadata (via DigitalSignatureAlgorithm and DigitalSignatureValue?), and on ExchangeCatalogue (via CertificateBlock?).

Verification API

// Create a verifier
IExchangeSetVerifier verifier = new ExchangeSetVerifier();

// Configure trust anchors (optional — pass trusted SA root certificates)
var trust = new TrustAnchorOptions
{
    // For development/testing, skip certificate chain validation:
    AllowUntrustedCertificates = true,

    // For production, supply IHO SA root certificates:
    // TrustedRoots = [saRootCert],
};

// Verify an exchange set
ExchangeSetVerificationResult result = await verifier.VerifyAsync(
    assetSource,    // IAssetSource (filesystem or ZIP)
    catalogue,      // ExchangeCatalogue (from ExchangeCatalogueReader)
    trust,
    cancellationToken);

// Inspect results
if (result.IsUnsigned)
{
    // No signatures present — exchange set is unsigned
}
else if (result.AllValid)
{
    // All files have valid signatures
}
else if (result.HasInvalidSignatures)
{
    // At least one file has an invalid or untrusted signature
    foreach (var file in result.FileResults)
    {
        Console.WriteLine($"{file.FileName}: {file.Outcome} — {file.Detail}");
    }
}

Verification outcomes

Trust anchor model

TrustAnchorOptions controls how certificate trust is evaluated:

• TrustedRoots — a list of X509Certificate2 instances representing trusted Scheme Administrator (SA) root certificates. A signing certificate's Issuer field is matched against these roots.
• AllowUntrustedCertificates — when true, signatures are verified for correctness but certificate chain validation is skipped. This is useful during development or when loading exchange sets from unknown sources.

The IHO publishes test SA certificates for interoperability testing. For production use, supply the official IHO SA root certificate.

Scope and limitations

• Verification only — signing/authoring of exchange sets is not yet implemented.
• Encryption is out of scope — Part 15 §3 Confidentiality (ENC permits, cell-level decryption) is not supported.
• File hashing uses streaming SHA-256 to avoid loading large HDF5 files into memory.

Installation

dotnet add package EncDotNet.S100.ExchangeSets