Create private key dose not work by c#

[bonnlee2024]

Result like this:
-----BEGIN OPENSSH PRIVATE KEY-----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-----END OPENSSH PRIVATE KEY-----

---

Core code like this:
private static string WriteOpenSshPrivateKey(RsaPrivateCrtKeyParameters privateKey, TextWriter writer1)
{
using (var ms = new MemoryStream())
{
using (var writer = new BinaryWriter(ms))
{
writer.Write(_encoding.GetBytes("openssh-key-v1\0"));
writer.Write(_encoding.GetBytes("none"));
writer.Write(_encoding.GetBytes("none"));
writer.Write(new byte[] { 1 });

            byte[] publicKey = GetRsaPublicKeyBlob(privateKey);
            writer.Write(publicKey);

            RsaPrivateCrtKeyParameters privateKeyParams = (RsaPrivateCrtKeyParameters)privateKey;

            MemoryStream privateKeyStream = new MemoryStream();
            using (BinaryWriter privateKeyWriter = new BinaryWriter(privateKeyStream))
            {
                var checkInt = new Random().Next();
                privateKeyWriter.Write(BitConverter.GetBytes(checkInt));
                privateKeyWriter.Write(BitConverter.GetBytes(checkInt));
                privateKeyWriter.Write(_encoding.GetBytes("ssh-rsa"));
                WriteMpInt(privateKeyWriter, privateKeyParams.Modulus);
                WriteMpInt(privateKeyWriter, privateKeyParams.PublicExponent);
                WriteMpInt(privateKeyWriter, privateKeyParams.Exponent);
                WriteMpInt(privateKeyWriter, privateKeyParams.P);
                WriteMpInt(privateKeyWriter, privateKeyParams.Q);
                WriteMpInt(privateKeyWriter, privateKeyParams.DQ);
                WriteMpInt(privateKeyWriter, privateKeyParams.QInv);
                privateKeyWriter.Write(System.Text.Encoding.ASCII.GetBytes("no comment"));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.Modulus));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.PublicExponent));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.Exponent));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.QInv));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.P));
                //privateKeyWriter.Write(GetBytes(privateKeyParams.Q));
                privateKeyWriter.Write(new byte[ms.Length % 8 == 0 ? 0 : 8 - (ms.Length % 8)]); // padding
            }

            byte[] privateKeyBlob = privateKeyStream.ToArray();
            writer.Write((uint)privateKeyBlob.Length);
            writer.Write(privateKeyBlob);
        }

        byte[] finalBlob = ms.ToArray();
        string base64Blob = Convert.ToBase64String(finalBlob);
        StringBuilder builder = new StringBuilder();
        builder.Append("-----BEGIN OPENSSH PRIVATE KEY-----\n");
        for (int i = 0; i < base64Blob.Length; i += 64)
        {
            int chunkSize = Math.Min(64, base64Blob.Length - i);
            builder.Append(base64Blob, i, chunkSize);
            builder.Append('\n');
        }
        builder.Append("-----END OPENSSH PRIVATE KEY-----\n");

        return builder.ToString();
    }
}

private static byte[] GetRsaPublicKeyBlob(RsaPrivateCrtKeyParameters privateKeyParams)
{
using (MemoryStream ms = new MemoryStream())
{
using (BinaryWriter writer = new BinaryWriter(ms))
{
writer.Write(Encoding.UTF8.GetBytes("ssh-rsa"));
writer.Write(GetBytes(privateKeyParams.Modulus));
writer.Write(GetBytes(privateKeyParams.PublicExponent));

        }
        return ms.ToArray();
    }
}

private static void WriteMpInt(BinaryWriter writer, Org.BouncyCastle.Math.BigInteger value)
{
var bytes = value.ToByteArrayUnsigned();
writer.Write(BitConverter.GetBytes(bytes.Length + 1)); // length
writer.Write((byte)(bytes[0] < 0 ? 0 : 0)); // leading zero for positive number
writer.Write(bytes); // value
}

[henrybarreto]

Hi, @bonnlee2024, how's you going?

It's nice to know you are working on ShellHub. However, we would to know why are you generating the keys using C#?

You could use make keygen to do it

[gustavosbarreto]

Closing this discussion due to no response. Feel free to reopen or start a new one if needed. Thanks!