TpmSanEncoder.cs

using System.Formats.Asn1;
using System.Security.Cryptography;

namespace Test
{
    internal static class TpmSanEncoder
    {
        internal static class Oids
        {
            public static readonly Oid Manufacturer = new ("2.23.133.2.1");
            public static readonly Oid Model        = new ("2.23.133.2.2");
            public static readonly Oid Version      = new ("2.23.133.2.3");
        }

        public static byte[] Encode(string manufacturer, string model, string version)
        {
            return Encode(
                (Oids.Manufacturer, manufacturer),
                (Oids.Model, model),
                (Oids.Version, version)
            );
        }

        public static byte[] Encode(params (Oid, string)[] items)
        {
            var writer = new AsnWriter(AsnEncodingRules.BER);

            using (writer.PushSequence())
            using (writer.PushSequence(new Asn1Tag(TagClass.ContextSpecific, 4, true)))
            {
                using (writer.PushSequence())
                {
                    foreach ((Oid oid, string value) in items)
                    {
                        WriteSet(writer, oid, value);
                    }
                }
            }

            return writer.Encode();
        }

        private static void WriteSet(AsnWriter writer, Oid oid, string text)
        {
            using (writer.PushSetOf())
            using (writer.PushSequence())
            {
                writer.WriteObjectIdentifier(oid.Value);
                writer.WriteCharacterString(UniversalTagNumber.UTF8String, text);
            }
        }
    }
}