ThirdPartyAPI/DigitalSignature/Utlis.cs

using Common.Models.DigitalSignature;
using JsonWebToken;
using System;
using System.Configuration;
using System.IO;

namespace DigitalSignature
{
    public class Utlis
    {
        private string publicKeyLocation {get;set;}
        private string privateKeyLocation { get; set; }
        public Utlis()
        {
            publicKeyLocation = ReadWebConfig("brac_Publickey", "");
            privateKeyLocation = ReadWebConfig("Jme_Privatekey", "");
        }

        //public static string MapPath(string path)
        //{
        //    return Path.Combine(AppDomain.CurrentDomain.BaseDirectory,
        //        path);
        //}

        public static string ReadWebConfig(string key, string defVal)
        {
            try
            {
                return ConfigurationManager.AppSettings[key].ToString() == null ? defVal : ConfigurationManager.AppSettings[key].ToString();
            }
            catch
            {
                return defVal;
            }
        }

        public  JwtResponse CreateToken(string payload)
        {
            JwtResponse jwtResponse = new JwtResponse();

            try
            {
                // RSA key for signing
                string pem = File.ReadAllText(@"D:\Office\SourceCodes\git-repo\JME\apis\ThirdPartyAPI\ThirdPartyAPIs\Keys\Brac\Jme_private_uat.pem");
                var signatureKey = Jwk.FromPem(pem);

                // RSA key for encryption
                //pem = File.ReadAllText(MapPath(publicKeyLocation));
                var encryptionKey = Jwk.FromPem(pem);

                string issuer = "testissuer";
                string subject = "testorgid";

                var now = DateTime.Now;
                var unixTimeSeconds = new DateTimeOffset(now).ToUnixTimeSeconds();

                var jws = new JwsDescriptor()
                {
                    SigningKey = signatureKey,
                    Algorithm = SignatureAlgorithm.RsaSha256,
                    ExpirationTime = now.AddMinutes(1440),
                    IssuedAt = now,
                    Issuer = issuer,
                    NotBefore = DateTime.Now,
                    Subject = subject,
                    Payload = new JwtObject()
                };
                jws.Payload.Add("Payload", payload);
                jws.AddClaim("iss", issuer);

                // Creates a JWE descriptor with all its properties
                var descriptor = new JweDescriptor<JwsDescriptor>()
                {
                    EncryptionKey = encryptionKey,
                    EncryptionAlgorithm = EncryptionAlgorithm.Aes256CbcHmacSha512,
                    Algorithm = KeyManagementAlgorithm.RsaOaep256,
                    Payload = jws
                };

                // Generates the UTF-8 string representation of the JWT
                var writer = new JwtWriter();
                var token = writer.WriteTokenString(descriptor);

                jwtResponse.Token = token;
                jwtResponse.ExpiresAt = unixTimeSeconds;

                return jwtResponse;
            }
            catch (Exception ex)
            {
                // write exception logs to database

                return jwtResponse;
            }
        }

        public  string ExtractPayloadFromToken(string token)
        {
            string jwtResponse = string.Empty;

            try
            {
                // RSA key for verification
                string pem = File.ReadAllText(publicKeyLocation);
                var signatureKey = Jwk.FromPem(pem);

                // RSA key for decryption
                pem = File.ReadAllText(privateKeyLocation);
                var decryptionKey = Jwk.FromPem(pem);

                string issuer = "testissuer";

                var policy = new TokenValidationPolicyBuilder()
                               .RequireSignature(signatureKey, SignatureAlgorithm.RsaSha256)
                               .Build();

                var reader = new JwtReader(decryptionKey);
                var result = reader.TryReadToken(token, policy);
                if (result.Succedeed)
                {
                    JwtProperty jwtProp = new JwtProperty();
                    var hasPayload = result.Token?.Payload?.TryGetValue("Payload", out jwtProp);

                    if (hasPayload != null && hasPayload.Value)
                    {
                        jwtResponse = jwtProp.Value.ToString();
                    }
                }
                return jwtResponse;
            }
            catch (Exception ex)
            {
                // write exception logs to database

                return jwtResponse;
            }
        }
    }
}