using System;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    private static string merchantID = "fiservar_ypf";

    private static string merchantKeyId = "113b3daf-463f-48da-92ec-617643dc9bf8";

    private static string merchantsecretKey = "JuhZWLi7rwNqtnnPVYAttbyIRdwaDWOPXVPhkD/SHIc=";

    private static string requestHost = "apitest.cybersource.com";

    private static string body = @"{'encryptionType':'None'}";

    private static string resource = "/flex/v1/keys";

​

    public static void Main()

    {

        string gmtDateTime = DateTime.Now.ToUniversalTime().ToString("r");

        Console.WriteLine(gmtDateTime);

        Console.WriteLine(GenerateDigest(body));

        Console.WriteLine(GenerateSignature(body, GenerateDigest(body), merchantKeyId, gmtDateTime, "post", resource));

    }

        /// <summary>

        /// This method return Digest value which is SHA-256 hash of payload that is BASE64 encoded

        /// </summary>

        /// <param name="request">Value from which to generate digest</param>

        /// <returns>String referring to a digest</returns>

        public static string GenerateDigest(string request)

        {

            string digest = "DIGEST_PLACEHOLDER";

​

            try

            {

                // Generate the Digest

                using (SHA256 sha256Hash = SHA256.Create())

                {

                    byte[] payloadBytes = sha256Hash.ComputeHash(Encoding.UTF8.GetBytes(request));

                    digest = Convert.ToBase64String(payloadBytes);

                    digest = "SHA-256=" + digest;

                }

            }

            catch (Exception ex)

            {

                Console.WriteLine("ERROR : " + ex.ToString());

            }

​

            return digest;

        }

    // This method returns value for paramter Signature which is then passed to Signature header

        // paramter 'Signature' is calucated based on below key values and then signed with SECRET KEY -

        // host: Sandbox (apitest.cybersource.com) or Production (api.cybersource.com) hostname

        // date: "HTTP-date" format as defined by RFC7231.

        // (request-target): Should be in format of httpMethod: path

        //    Example: "post /pts/v2/payments"

        // Digest: Only needed for POST calls.

        //    digestString = BASE64( HMAC-SHA256 ( Payload ));

        //    Digest: “SHA-256=“ + digestString;

        // v-c-merchant-id: set value to Cybersource Merchant ID

        //    This ID can be found on EBC portal

        public static string GenerateSignature(string request, string digest, string keyid, string gmtDateTime, string method, string resource)

        {

            StringBuilder signatureHeaderValue = new StringBuilder();

            string algorithm = "HmacSHA256";

            string postHeaders = "host date (request-target) digest v-c-merchant-id";

            string getHeaders = "host date (request-target) v-c-merchant-id";

            string url = "https://" + requestHost + resource;

            string getRequestTarget = method + " " + resource;

            string postRequestTarget = method + " " + resource;

​

            try

            {

                // Generate the Signature

                StringBuilder signatureString = new StringBuilder();

                signatureString.Append('\n');

                signatureString.Append("host");

                signatureString.Append(": ");

                signatureString.Append(requestHost);

                signatureString.Append('\n');

                signatureString.Append("date");

                signatureString.Append(": ");

                signatureString.Append(gmtDateTime);

                signatureString.Append('\n');

                signatureString.Append("(request-target)");

                signatureString.Append(": ");

​

                if (method.Equals("post"))

                {

                    signatureString.Append(postRequestTarget);

                    signatureString.Append('\n');

                    signatureString.Append("digest");

                    signatureString.Append(": ");

                    signatureString.Append(digest);

                }

                else

                {

                    signatureString.Append(getRequestTarget);

                }

​

                signatureString.Append('\n');

                signatureString.Append("v-c-merchant-id");

                signatureString.Append(": ");

                signatureString.Append(merchantID);

                signatureString.Remove(0, 1);

​

                byte[] signatureByteString = Encoding.UTF8.GetBytes(signatureString.ToString());

​

                byte[] decodedKey = Convert.FromBase64String(merchantsecretKey);

​

                HMACSHA256 aKeyId = new HMACSHA256(decodedKey);

​

                byte[] hashmessage = aKeyId.ComputeHash(signatureByteString);

                string base64EncodedSignature = Convert.ToBase64String(hashmessage);

​

                signatureHeaderValue.Append("keyid=\"" + merchantKeyId + "\"");

                signatureHeaderValue.Append(", algorithm=\"" + algorithm + "\"");

​

                if (method.Equals("post"))

                {

                    signatureHeaderValue.Append(", headers=\"" + postHeaders + "\"");

                }

                else if (method.Equals("get"))

                {

                    signatureHeaderValue.Append(", headers=\"" + getHeaders + "\"");

                }

​

                signatureHeaderValue.Append(", signature=\"" + base64EncodedSignature + "\"");

​

            }

            catch (Exception ex)

            {

                Console.WriteLine("ERROR : " + ex.ToString());

            }

​

            return signatureHeaderValue.ToString();

        }

​

}