Как создать RsaSecurityKey из пары открытых / закрытых ключей

Question

Как я могу создать RsaSecurityKey из пары открытых / закрытых ключей. Мне нужно создать токен идентификатора JWT

Мой образец пары ключ-значение приведен в методе

public string GetIdTokenStringNew(Dictionary<string, object> inputClaims, string publicKey, string privateKey )
        {
            string result = null;
            try
            {
                var tokenHandler = new JwtSecurityTokenHandler();                

                publicKey = @"-----BEGIN PUBLIC KEY-----
MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANPCGYnVEa1jQPMSHXST8NVIrcAYZcWr
..............
-----END PUBLIC KEY-----
";

                privateKey = @"-----BEGIN ENCRYPTED PRIVATE KEY-----
MIIBrzBJBgkqhkiG9w0BBQ0wPDAbBgkqhkiG9w0BBQwwDgQIa3E4RUhvGGwCAggA
MB0GCWCGSAFlAwQBKgQQnfLhTMhpN7BE0A+viaWeWwSCAWD2yFBSGAP6boVzCOqg
41IoRHrZHgTQVbySuruav5nM3eMe3psHD0C4Tbyj4av3UnD2/ebZz8f9IiObJ45a
................................................................
....
-----END ENCRYPTED PRIVATE KEY-----";


                List<Claim> claims = new List<Claim>();

                foreach (var o in inputClaims)
                {
                    string val = null;
                    if (o.Value != null)
                    {
                        Type t = o.Value.GetType();
                        bool isDict = t.IsGenericType /*&& t.GetGenericTypeDefinition() == typeof(Dictionary<,>)*/;
                        if (isDict)
                        {
                            val = JsonSerializer.Serialize(o.Value);
                        }
                        else
                        {
                            val = o.Value.ToString();
                        }
                    }
                    claims.Add(new Claim(o.Key, val));
                }

                var rsaParameters = new RSAParameters();// it should be from public /private key               
                var securitykey = new RsaSecurityKey(rsaParameters);
                var tokenDescriptor = new SecurityTokenDescriptor
                {
                    Subject = new ClaimsIdentity(claims),
                    Expires = DateTime.UtcNow.AddSeconds(60 * 5),
                    SigningCredentials = new SigningCredentials(securitykey, SecurityAlgorithms.RsaSha256),
                    Audience = "....",
                    Issuer = "..."
                };
                var additionalheader = new Dictionary<string, object>
                {
                    { "kid", "***" }
                };
                tokenDescriptor.AdditionalHeaderClaims = additionalheader;                
                var token = tokenHandler.CreateToken(tokenDescriptor);
                if (token != null && token is JwtSecurityToken)
                {
                    result = (token as JwtSecurityToken).RawData;
                }
            }
            catch (Exception ex)
            {

            }
            return result;
        }