KDuma.Pcf.Sig 0.0.9

KDuma.Pcf.Sig

.NET implementation of PCF-SIG v1.0, the PCF Cryptographic Signatures profile. Mirrors the normative specification and the Rust reference implementation field-for-field.

Install

dotnet add package KDuma.Pcf
dotnet add package KDuma.Pcf.Sig

What it adds

Two new PCF partition types layered on top of the KDuma.Pcf container, without changing the PCF byte format:

A Manifest binds the protected fields of each covered partition: Uid, PartitionType, Label, UsedBytes, DataHashAlgo, DataHash. It does NOT bind StartOffset or MaxLength, so PCF compaction and other relocations preserve signature validity as long as partition bytes do not change.

Algorithm support

Algorithms marked registry only are recognised at parse time and reported as ManifestVerdict.Unverifiable (with UnverifiableReason.UnsupportedSigAlgo) rather than Malformed. Adding a full implementation for any of them is a pure addition that does not touch the on-disk format.

Hash algorithm constraint: signed partitions MUST use a cryptographic DataHashAlgo (SHA-256, SHA-512, BLAKE3). The Writer refuses to sign weakly-hashed partitions; the Verifier rejects them per entry.

Usage

using Pcf;
using Pcf.Sig;
using System.IO;

var c = Container.Create(new MemoryStream());
var alpha = new byte[16] { 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
                           0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11 };
c.AddPartition(0x10, alpha, "alpha",
    System.Text.Encoding.UTF8.GetBytes("Hello, PCF-SIG!"), 0, HashAlgo.Sha256);

var seed = new byte[32]; for (int i = 0; i < 32; i++) seed[i] = 0x42;
var signer = SigningMaterial.Ed25519FromSeed(seed);
SignPartitions.Run(
    c, signer, new[] { alpha },
    /* sigPartitionUid: */ new byte[16] { 0x33,0x33,0x33,0x33,0x33,0x33,0x33,0x33, 0x33,0x33,0x33,0x33,0x33,0x33,0x33,0x33 },
    /* keyPartitionUid: */ new byte[16] { 0x22,0x22,0x22,0x22,0x22,0x22,0x22,0x22, 0x22,0x22,0x22,0x22,0x22,0x22,0x22,0x22 },
    signedAtUnixSeconds: 0,
    sigLabel: "pcfsig",
    keyLabel: "pcfkey");

foreach (var report in Verify.AllWithRecheck(c))
{
    if (report.Verdict == ManifestVerdict.Valid)
    {
        System.Console.WriteLine(
            $"signature valid; {report.Entries.Count} entries covered");
    }
}

Cross-port test vector parity

The shipped testdata/canonical.bin is byte-identical to the canonical vector produced by the Rust reference, the TypeScript port and the PHP port. SHA-256: b158e2f5b160d72cea3226af2041f8d18aa75b3db6cb85faeca5df7879871307.

Dependencies

• KDuma.Pcf — the PCF base container library (same version as pcf-sig).
• BouncyCastle.Cryptography v2.4+ — actively maintained main BouncyCastle fork; ships RFC 8032 Ed25519 (Org.BouncyCastle.Math.EC.Rfc8032.Ed25519) and targets netstandard2.0.
• System.Security.Cryptography (BCL) — SHA-256 for fingerprints.

The library targets netstandard2.0 to match the PCF base; tests target net8.0.