git.stella-ops.org/src/__Libraries/StellaOps.Cryptography.Plugin.EIDAS/LocalEidasProvider.cs

// SPDX-License-Identifier: AGPL-3.0-or-later
// Sprint: SPRINT_4100_0006_0002 - eIDAS Crypto Plugin

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using StellaOps.Cryptography.Plugin.EIDAS.Configuration;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;

namespace StellaOps.Cryptography.Plugin.EIDAS;

/// <summary>
/// Local eIDAS signing provider using PKCS#12 keystores.
/// Suitable for development and AdES-level signatures.
/// </summary>
public class LocalEidasProvider
{
    private readonly ILogger<LocalEidasProvider> _logger;
    private readonly LocalSigningOptions? _options;
    private X509Certificate2? _certificate;

    public LocalEidasProvider(
        ILogger<LocalEidasProvider> logger,
        IOptions<EidasOptions> options)
    {
        _logger = logger;
        _options = options.Value.Local;
    }

    /// <summary>
    /// Local signing with PKCS#12 certificate (stub implementation).
    /// </summary>
    public async Task<byte[]> LocalSignAsync(
        byte[] data,
        string algorithmId,
        EidasKeyConfig keyConfig,
        CancellationToken cancellationToken)
    {
        _logger.LogDebug("Local eIDAS signing: keyId={KeyId}, algorithm={Algorithm}, dataLength={Length}",
            keyConfig.KeyId, algorithmId, data.Length);

        if (_options == null)
        {
            throw new InvalidOperationException("Local signing options not configured");
        }

        // Load certificate from PKCS#12 keystore (cached)
        _certificate ??= LoadCertificate(_options);

        // Stub implementation - in production, use actual certificate signing
        _logger.LogWarning("Using stub local signing - replace with actual PKCS#12 signing in production");

        // Compute hash
        var hash = algorithmId.Contains("SHA256") ? SHA256.HashData(data) : SHA512.HashData(data);

        // Stub: Create mock signature
        var stubSignature = new byte[64]; // ECDSA-P256 signature
        RandomNumberGenerator.Fill(stubSignature);

        _logger.LogInformation("Local eIDAS signature created (stub): keyId={KeyId}, signatureLength={Length}",
            keyConfig.KeyId, stubSignature.Length);

        await Task.CompletedTask; // For async signature
        return stubSignature;

        // Production implementation:
        // using var rsa = _certificate.GetRSAPrivateKey();
        // using var ecdsa = _certificate.GetECDsaPrivateKey();
        //
        // return algorithmId switch
        // {
        //     "RSA-PSS-2048" or "RSA-PSS-4096" => rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pss),
        //     "ECDSA-P256" or "ECDSA-P384" or "ECDSA-P521" => ecdsa.SignData(data, HashAlgorithmName.SHA256),
        //     _ => throw new NotSupportedException($"Algorithm {algorithmId} not supported for local signing")
        // };
    }

    /// <summary>
    /// Local verification with PKCS#12 certificate (stub implementation).
    /// </summary>
    public async Task<bool> LocalVerifyAsync(
        byte[] data,
        byte[] signature,
        string algorithmId,
        EidasKeyConfig keyConfig,
        CancellationToken cancellationToken)
    {
        _logger.LogDebug("Local eIDAS verification: keyId={KeyId}, algorithm={Algorithm}",
            keyConfig.KeyId, algorithmId);

        if (_options == null)
        {
            throw new InvalidOperationException("Local signing options not configured");
        }

        // Load certificate from PKCS#12 keystore
        _certificate ??= LoadCertificate(_options);

        // Stub: Always return true
        _logger.LogWarning("Using stub local verification - replace with actual PKCS#12 verification in production");
        await Task.Delay(10, cancellationToken); // Simulate crypto operation

        _logger.LogInformation("Local eIDAS verification complete (stub): keyId={KeyId}, valid=true",
            keyConfig.KeyId);

        return true;

        // Production implementation:
        // using var rsa = _certificate.GetRSAPublicKey();
        // using var ecdsa = _certificate.GetECDsaPublicKey();
        //
        // return algorithmId switch
        // {
        //     "RSA-PSS-2048" or "RSA-PSS-4096" => rsa.VerifyData(data, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pss),
        //     "ECDSA-P256" or "ECDSA-P384" or "ECDSA-P521" => ecdsa.VerifyData(data, signature, HashAlgorithmName.SHA256),
        //     _ => throw new NotSupportedException($"Algorithm {algorithmId} not supported for local verification")
        // };
    }

    private X509Certificate2 LoadCertificate(LocalSigningOptions options)
    {
        _logger.LogDebug("Loading eIDAS certificate from keystore: path={Path}, type={Type}",
            options.Path, options.Type);

        if (!File.Exists(options.Path))
        {
            throw new FileNotFoundException($"eIDAS keystore not found: {options.Path}");
        }

        try
        {
            if (options.Type.Equals("PKCS12", StringComparison.OrdinalIgnoreCase))
            {
                var cert = X509CertificateLoader.LoadPkcs12FromFile(
                    options.Path,
                    options.Password,
                    X509KeyStorageFlags.Exportable);

                _logger.LogInformation("eIDAS certificate loaded: subject={Subject}, serial={Serial}, expires={Expires}",
                    cert.Subject, cert.SerialNumber, cert.NotAfter);

                return cert;
            }
            else if (options.Type.Equals("PEM", StringComparison.OrdinalIgnoreCase))
            {
                // Load PEM certificate (requires separate key file)
                var certPem = File.ReadAllText(options.Path);
                var cert = X509Certificate2.CreateFromPem(certPem);

                _logger.LogInformation("eIDAS PEM certificate loaded: subject={Subject}",
                    cert.Subject);

                return cert;
            }
            else
            {
                throw new NotSupportedException($"Keystore type '{options.Type}' not supported");
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to load eIDAS certificate from keystore");
            throw;
        }
    }
}