using Org.BouncyCastle.Asn1;

using Org.BouncyCastle.Asn1.EdEC;

using Org.BouncyCastle.Asn1.Pkcs;

using Org.BouncyCastle.Asn1.X509;

using Org.BouncyCastle.Crypto;

using Org.BouncyCastle.Crypto.Generators;

using Org.BouncyCastle.Crypto.Parameters;

using Org.BouncyCastle.OpenSsl;

using Org.BouncyCastle.Security;

using System;

using System.IO;

​

public class Program

{

    public static void Main()

    {

        AsymmetricCipherKeyPair keyPair = GenerateEd25519KeyPair();

        Ed25519PrivateKeyParameters privateKey = (Ed25519PrivateKeyParameters)keyPair.Private;

        SavePrivateKeyToPem(privateKey);

        SavePrivateKeyToPemPkcs8(privateKey);

    }

​

    static void SavePrivateKeyToPem(Ed25519PrivateKeyParameters privateKey)

    {

        using (TextWriter textWriter = new StringWriter())

        {

            var pemWriter = new PemWriter(textWriter);

            pemWriter.WriteObject(privateKey);

            Console.WriteLine(textWriter.ToString());

        }

    }

​

    static void SavePrivateKeyToPemPkcs8(Ed25519PrivateKeyParameters privateKey)

    {

        PrivateKeyInfo privateKeyInfo = new PrivateKeyInfo(new AlgorithmIdentifier(EdECObjectIdentifiers.id_Ed25519), new DerOctetString(privateKey.GetEncoded())); // fix: add this line

        using (TextWriter textWriter = new StringWriter())

        {

            var pemWriter = new PemWriter(textWriter);

            pemWriter.WriteObject(privateKeyInfo);

            Console.WriteLine(textWriter.ToString());

        }

    }

​

    static AsymmetricCipherKeyPair GenerateEd25519KeyPair()

    {

        var keyGen = new Ed25519KeyPairGenerator();

        keyGen.Init(new KeyGenerationParameters(new SecureRandom(), 256));

        return keyGen.GenerateKeyPair();

    }

}