public async Task<TokenResponse> GenerateAsync(Client client, TokenRequest tokenRequest, string issuer, string audience)
        {
            var ed25519pkcs8 = await File.ReadAllTextAsync("private.pem");

            var privatePemReader = new PemReader(new StringReader(ed25519pkcs8));
            var ed25519pkcs8Parameters = (Ed25519PrivateKeyParameters)privatePemReader.ReadObject();
            ISigner signer = new Ed25519Signer();
            signer.Init(true, ed25519pkcs8Parameters);

            var pasetoToken = new PasetoBuilder()
                .Use(ProtocolVersion.V4, Purpose.Public)
                .WithSecretKey(signer.GenerateSignature())
                .Issuer(issuer)
                .Subject(tokenRequest.ClientId)
                .Audience(audience)
                .NotBefore(DateTime.UtcNow)
                .IssuedAt(DateTime.UtcNow)
                .Expiration(DateTime.UtcNow.AddSeconds(client.AccessTokenLifetime))
                .TokenIdentifier(Guid.NewGuid().ToString())
                .AddClaim("client_id", tokenRequest.ClientId)
                .AddClaim("scopes", tokenRequest.Scopes)
                .Encode();

            return new TokenResponse
            {
                AccessToken = pasetoToken,
                Lifetime = client.AccessTokenLifetime,
                Scope = tokenRequest.Scopes
            };
        }

// and test controller for verifying
        // test
        [HttpGet]
        public IActionResult DecodePaseto([FromQuery] string token)
        {
            var ed25519x509 = System.IO.File.ReadAllText("public.pem");

            var publicPemReader = new PemReader(new StringReader(ed25519x509));
            var ed25519x509Parameters = (Ed25519PublicKeyParameters)publicPemReader.ReadObject();

            var paseto = new PasetoBuilder()
                .Use(ProtocolVersion.V4, Purpose.Public)
                .WithPublicKey(ed25519x509Parameters.GetEncoded())
                .Decode(token);

            return Ok(JsonConvert.SerializeObject(paseto));
        }