DAT C# Library ​

// singleton — dispose on shutdown (stops the sync loop and releases the HttpClient)
DatCmsManager manager = await DatCmsManager.Builder()
    .Host("localhost")
    .Port(8088)
    //.IntervalOff() // auto sync off
    .IntervalSeconds(60)
    .Token("12345678901b")
    //.Logger(logger)
    .BuildAsync();

// BuildAsync always returns a manager, even when the first sync failed — it
// becomes usable once the network recovers. Ask separately whether it synced.
DatException? syncError = manager.LastError;
if (syncError is not null)
{
    // A permanent failure (bad token, wrong URL) will never resolve on its own.
    Console.WriteLine($"initial sync failed: {syncError.Code} (retry={syncError.Retry})");
}
Console.WriteLine($"synced version: {manager.GetVersion()}");

// manual sync
// await manager.Sync();

string plain = "Unicode 유니코드 ユニコード 万国码 يونيكود यूनिकोड Юникод 🦄💻";
string secure = "Ciphertext 암호문 暗号文 密文 Шифротекст Texte chiffré Geheimtext نص مشفر सिफरपाठ 🔐";

Console.WriteLine("plain : " + plain);
Console.WriteLine("secure : " + secure);

// issue dat
string dat = manager.Issue(plain, secure);
Console.WriteLine("dat : " + dat);

// parse dat
Payload payload = manager.Parse(dat);

string payloadPlain = payload.Plain;
string payloadSecure = payload.Secure;

Console.WriteLine("payload plain : " + payloadPlain);
Console.WriteLine("payload secure : " + payloadSecure);

using var datManager = DatManager.NewInstance();

// (cid, issuanceStart, issuanceDuration, datTtl, signatureAlgorithm, cryptoAlgorithm)
long now = Unixtime.Now();
using var cert = DatCertificate.Generate(
    0,
    now - 10,
    7200,
    1800,
    DatSignatureAlgorithm.EcdsaP256,
    DatCryptoAlgorithm.IvAes128Gcm
);

// Imports copies the certificates, so the caller keeps ownership of `cert`.
datManager.Imports(new List<DatCertificate> { cert }, false);

string plain = "Unicode 유니코드 ユニコード 万国码 يونيكود यूनिकोड Юникод 🦄💻";
string secure = "Ciphertext 암호문 暗号文 密文 Шифротекст Texte chiffré Geheimtext نص مشفر सिफरपाठ 🔐";

string dat = datManager.Issue(plain, secure);

Payload payload = datManager.Parse(dat);

Assert.That(payload.Plain, Is.EqualTo(plain));
Assert.That(payload.Secure, Is.EqualTo(secure));

TestContext.Progress.WriteLine($"PARSE DAT: {dat}");
TestContext.Progress.WriteLine($"plain: {payload.Plain}");
TestContext.Progress.WriteLine($"secure: {payload.Secure}");

// Expiry, forgery and malformed input each need a different response.
try
{
    Payload payload = manager.Parse(dat);
}
catch (DatException e) when (e.Code == DatErrorCode.TokenExpired)
{
    // Normal end of life — let the client refresh its token.
}
catch (DatException e) when (e.SecurityEvent)
{
    // DAT_SIG_MISMATCH or DAT_CRYPTO_TAG_MISMATCH: forged or tampered with.
    Console.Error.WriteLine($"[SECURITY] {e.Code}");
}
catch (DatException e)
{
    // Anything else: just reject the request.
    Console.Error.WriteLine($"rejected: {e.Code}");
}

try
{
    string dat = manager.Issue(plain, secure);
}
catch (DatException e)
{
    // Never retry a permanent failure — it will not resolve on its own.
    if (e.Retry == DatRetry.Transient)
    {
        // back off, then retry
    }

    // Why issuing failed is chained, not folded into the outer code.
    // Waiting helps for DAT_CERT_NOT_YET_ISSUABLE and nothing else.
    if (e.Code == DatErrorCode.ManagerNoIssuableCertificate)
    {
        Console.Error.WriteLine($"cannot issue: {DatException.CodeOf(e.InnerException)}");
    }
}