====== NativeCryptoProvider ======

**Namespace:** ''WvdS.System.Security.Cryptography.Providers''

P/Invoke-based crypto provider for server and desktop applications. Communicates directly with OpenSSL 3.6 via Platform Invocation Services.

===== Overview =====

The ''NativeCryptoProvider'' is the default provider for:

  * Blazor Server
  * ASP.NET Core
  * Desktop applications (Windows, Linux, macOS)
  * Console applications
  * Windows Services / Linux Daemons

===== Properties =====

^ Property ^ Type ^ Description ^
| ''Name'' | string | ''%%"Native (P/Invoke)"%%'' |
| ''IsAvailable'' | bool | ''true'' if OpenSSL 3.6 is reachable |

===== Initialization =====

<code csharp>
using WvdS.System.Security.Cryptography.Providers;

// Create provider
var provider = new NativeCryptoProvider();

// Initialize (loads OpenSSL)
await provider.InitializeAsync();

// Check if available
if (provider.IsAvailable)
{
    Console.WriteLine($"Provider: {provider.Name}");
    Console.WriteLine($"OpenSSL: {provider.GetOpenSslVersion()}");
}
</code>

===== ML-DSA Operations =====

==== GenerateMlDsaKeyPairAsync ====

Generates an ML-DSA key pair.

<code csharp>
var (publicKey, privateKey) = await provider.GenerateMlDsaKeyPairAsync("ML-DSA-65");

// Supported algorithms:
// - "ML-DSA-44" (NIST Level 1)
// - "ML-DSA-65" (NIST Level 3, recommended)
// - "ML-DSA-87" (NIST Level 5)
</code>

==== SignMlDsaAsync ====

Signs data with ML-DSA.

<code csharp>
byte[] data = Encoding.UTF8.GetBytes("Important data");
byte[] signature = await provider.SignMlDsaAsync(data, privateKey);
</code>

==== VerifyMlDsaAsync ====

Verifies an ML-DSA signature.

<code csharp>
bool isValid = await provider.VerifyMlDsaAsync(data, signature, publicKey);
</code>

===== ML-KEM Operations =====

==== GenerateMlKemKeyPairAsync ====

Generates an ML-KEM key pair.

<code csharp>
var (publicKey, privateKey) = await provider.GenerateMlKemKeyPairAsync("ML-KEM-768");

// Supported algorithms:
// - "ML-KEM-512" (NIST Level 1)
// - "ML-KEM-768" (NIST Level 3, recommended)
// - "ML-KEM-1024" (NIST Level 5)
</code>

==== EncapsulateAsync ====

Encapsulates a shared secret with the public key.

<code csharp>
var (sharedSecret, ciphertext) = await provider.EncapsulateAsync(recipientPublicKey);

// sharedSecret: 32 bytes symmetric key
// ciphertext: Send to recipient
</code>

==== DecapsulateAsync ====

Decapsulates the shared secret.

<code csharp>
byte[] sharedSecret = await provider.DecapsulateAsync(ciphertext, privateKey);
</code>

===== Certificate Operations =====

==== CreateEphemeralCertificateAsync ====

Creates an ephemeral ML-DSA certificate.

<code csharp>
var (pubKey, privKey) = await provider.GenerateMlDsaKeyPairAsync();

byte[] certBytes = await provider.CreateEphemeralCertificateAsync(
    "CN=Ephemeral Test",
    TimeSpan.FromHours(24),
    privKey);

var cert = new X509Certificate2(certBytes);
</code>

==== SignCertificateAsync ====

Signs TBS certificate data with ML-DSA.

<code csharp>
byte[] tbsCertificate = GetTbsCertificate();
byte[] signedCert = await provider.SignCertificateAsync(tbsCertificate, privateKey);
</code>

===== Method Overview =====

^ Method ^ Parameters ^ Return ^
| ''InitializeAsync()'' | - | Task |
| ''GetOpenSslVersion()'' | - | string |
| ''GenerateMlDsaKeyPairAsync'' | string algorithm | Task<(byte[], byte[])> |
| ''SignMlDsaAsync'' | byte[] data, byte[] privateKey | Task<byte[]> |
| ''VerifyMlDsaAsync'' | byte[] data, byte[] signature, byte[] publicKey | Task<bool> |
| ''GenerateMlKemKeyPairAsync'' | string algorithm | Task<(byte[], byte[])> |
| ''EncapsulateAsync'' | byte[] publicKey | Task<(byte[], byte[])> |
| ''DecapsulateAsync'' | byte[] ciphertext, byte[] privateKey | Task<byte[]> |
| ''CreateEphemeralCertificateAsync'' | string subject, TimeSpan validity, byte[] privateKey | Task<byte[]> |
| ''SignCertificateAsync'' | byte[] tbsCertificate, byte[] privateKey | Task<byte[]> |

===== OpenSSL Path Configuration =====

<code csharp>
// Set the path before InitializeAsync()
CryptoConfig.OpenSslPath = @"C:\OpenSSL\bin";

var provider = new NativeCryptoProvider();
await provider.InitializeAsync();
</code>

**Default search paths:**

^ Operating System ^ Paths ^
| Windows | ''%%.\%%'', ''%%C:\OpenSSL\bin%%'', ''%%PATH%%'' |
| Linux | ''%%/usr/local/lib64%%'', ''%%/usr/lib/x86_64-linux-gnu%%'' |
| macOS | ''%%/opt/homebrew/lib%%'', ''%%/usr/local/lib%%'' |

===== Performance Notes =====

<note tip>
**P/Invoke Performance:**

  * Synchronous execution in native code
  * Task wrapper for API consistency with WasmCryptoProvider
  * Minimal overhead through direct memory access
  * Thread-safe through OpenSSL's internal synchronization
</note>

===== Complete Example =====

<code csharp>
using WvdS.System.Security.Cryptography.Providers;

// 1. Initialize provider
var provider = new NativeCryptoProvider();
await provider.InitializeAsync();

Console.WriteLine($"OpenSSL: {provider.GetOpenSslVersion()}");

// 2. ML-KEM Key Exchange
var (alicePublic, alicePrivate) = await provider.GenerateMlKemKeyPairAsync();
var (bobPublic, bobPrivate) = await provider.GenerateMlKemKeyPairAsync();

// Alice encapsulates for Bob
var (aliceSecret, ciphertext) = await provider.EncapsulateAsync(bobPublic);

// Bob decapsulates
var bobSecret = await provider.DecapsulateAsync(ciphertext, bobPrivate);

// Shared secrets are identical
Console.WriteLine($"Keys match: {aliceSecret.SequenceEqual(bobSecret)}");

// 3. ML-DSA Signature
var (sigPubKey, sigPrivKey) = await provider.GenerateMlDsaKeyPairAsync();

byte[] message = Encoding.UTF8.GetBytes("Important message");
byte[] signature = await provider.SignMlDsaAsync(message, sigPrivKey);

bool isValid = await provider.VerifyMlDsaAsync(message, signature, sigPubKey);
Console.WriteLine($"Signature valid: {isValid}");
</code>

===== Security Notes =====

<note warning>
  * Requires OpenSSL 3.6.0 or higher with PQ algorithms
  * Private keys are held in process memory
  * Keys are not automatically deleted at application end
  * For highest security: explicitly delete keys with ''CryptographicOperations.ZeroMemory''
</note>

===== See Also =====

  * [[.:start|Providers Namespace]]
  * [[.:icryptoprovider|ICryptoProvider]]
  * [[.:wasmcryptoprovider|WasmCryptoProvider]]
  * [[.:cryptoproviderfactory|CryptoProviderFactory]]
  * [[..:interop:opensslinterop|OpenSslInterop]]

----
//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//