• Sample Hmac Sha256 encoding in Php 5

  
  <?php
  
  …
  
  // Seal computation thanks to hash sorted data hash with merchant key
  
  $data_to_send= utf8_encode($data)
  
  $seal=hash_hmac('sha256', $data_to_send, $secretKey);
  
  …
  …
  
  ?> 

  data_to_send and secretKey must use a UTF-8 character set. Please refer to the utf8_encode function for the conversion of ISO-8859-1 characters in UTF-8.

• Sample Hmac Sha256 encoding in Java

  
  import java.security.InvalidKeyException;
  import java.security.NoSuchAlgorithmException;
  
  import javax.crypto.Mac;
  import javax.crypto.spec.SecretKeySpec;
  
  public class ExampleHMACSHA256 {
  
  /**
   * table to convert a nibble to a hex char.
   */
  static final char[] hexChar = {
     '0' , '1' , '2' , '3' ,
     '4' , '5' , '6' , '7' ,
     '8' , '9' , 'a' , 'b' ,
     'c' , 'd' , 'e' , 'f'};
  
  /**
   * Fast convert a byte array to a hex string
   * with possible leading zero.
   * @param b array of bytes to convert to string
   * @return hex representation, two chars per byte.
   */
  public static String encodeHexString ( byte[] b )
     {
     StringBuffer sb = new StringBuffer( b.length * 2 );
     for ( int i=0; i<b.length; i++ )
        {
        // look up high nibble char
        sb.append( hexChar [( b[i] & 0xf0 ) >>> 4] );
  
        // look up low nibble char
        sb.append( hexChar [b[i] & 0x0f] );
        }
     return sb.toString();
     }
  
  /**
   * Computes the seal
   * @param Data the parameters to cipher
   * @param secretKey the secret key to append to the parameters 
   * @return hex representation of the seal, two chars per byte.
   */
  public static String computeSeal(String data, String secretKey) throws Exception
  {
    Mac hmacSHA256 = Mac.getInstance("HmacSHA256");
    SecretKeySpec keySpec = new SecretKeySpec(secretKey.getBytes(), "HmacSHA256");
    hmacSHA256.init(keySpec);
  
    return encodeHexString(hmacSHA256.doFinal(data.getBytes()));
  }
  
  /**
   * @param args
   */
  public static void main(String[] args) {
  try {
  System.out.println (computeSeal("parameters", "key"));
  } catch (Exception e) {
  e.printStackTrace();
  }
  }
  
  }

• Sample Hmac Sha256 encoding in .net

  (Carried out using a simple form called "Form1" containing two text fields to enter data and txtSecretKey, and another field to display lblHEX).

  
  using System;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.Data;
  using System.Drawing;
  using System.Text;
  using System.Windows.Forms;
  using System.Security.Cryptography;
  
  namespace ExampleDotNET
  {
      public partial class Form1 : Form
      {
          public Form1()
          {
              InitializeComponent();
          }
  
          private void cmdGO_Click(object sender, EventArgs e)
          {
              String sChaine = data.Text;
              UTF8Encoding utf8 = new UTF8Encoding();
              Byte[] encodedBytes = utf8.GetBytes(sChaine);
          
              byte[] shaResult;
              
              HMAC hmac = new HMAC.Create("HMACSHA256");
              var key = "YourSecretKey";
              hmac.Key = utf8.GetBytes(key); 
              hmac.Initialize();
  
              shaResult = hmac.ComputeHash(encodedBytes);
  
              lblHEX.Text = ByteArrayToHEX(shaResult);
          }
  
          private string ByteArrayToHEX(byte[] ba)
          {
              StringBuilder hex = new StringBuilder(ba.Length * 2);
              foreach (byte b in ba)
                  hex.AppendFormat("{0:x2}", b);
              return hex.ToString();
          }
  
      }
  }

• Sample Sha256 encoding in Php 5

<?php
echo hash('sha256', $data.$secretKey);
?> 

The UTF-8 character set should be used for the Data and secretKey data. To convert ISO-8859-1 to UTF-8, use the utf8_encode function.

• Sample Sha256 encoding in Java

import java.security.MessageDigest;

public class ExampleSHA256 {

/**
 * table to convert a nibble to a hex char.
 */
static final char[] hexChar = {
   '0' , '1' , '2' , '3' ,
   '4' , '5' , '6' , '7' ,
   '8' , '9' , 'a' , 'b' ,
   'c' , 'd' , 'e' , 'f'};

/**
 * Fast convert a byte array to a hex string
 * with possible leading zero.
 * @param b array of bytes to convert to string
 * @return hex representation, two chars per byte.
 */
public static String encodeHexString ( byte[] b )
   {
   StringBuffer sb = new StringBuffer( b.length * 2 );
   for ( int i=0; i<b.length; i++ )
      {
      // look up high nibble char
      sb.append( hexChar [( b[i] & 0xf0 ) >>> 4] );

      // look up low nibble char
      sb.append( hexChar [b[i] & 0x0f] );
      }
   return sb.toString();
   }

/**
 * Computes the seal
 * @param Data the parameters to cipher
 * @param secretKey the secret key to append to the parameters 
 * @return hex representation of the seal, two chars per byte.
 */
public static String computeSeal(String Data, String secretKey) throws Exception
{
  MessageDigest md = MessageDigest.getInstance("SHA-256");
  md.update((Data+secretKey).getBytes("UTF-8"));

  return encodeHexString(md.digest());
}

/**
 * @param args
 */
public static void main(String[] args) {
try {
System.out.println (computeSeal("parameters", "key"));
} catch (Exception e) {
e.printStackTrace();
}
}
}

• Sample Sha256 encoding in .NET

Completed using a simple form called "Form 1" containing two text fields to be filled in: data, txtSecretKey and another one to be displayed: lblHEX.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Security.Cryptography;

namespace ExampleDotNET
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void cmdGO_Click(object sender, EventArgs e)
        {
            String sChaine = data.Text + txtSecretKey.Text;
            UTF8Encoding utf8 = new UTF8Encoding();
            Byte[] encodedBytes = utf8.GetBytes(sChaine);
        
            byte[] shaResult;
            SHA256 shaM = new SHA256Managed();
            shaResult = shaM.ComputeHash(encodedBytes);

            lblHEX.Text = ByteArrayToHEX(shaResult);
        }

        private string ByteArrayToHEX(byte[] ba)
        {
            StringBuilder hex = new StringBuilder(ba.Length * 2);
            foreach (byte b in ba)
                hex.AppendFormat("{0:x2}", b);
            return hex.ToString();
        }

    }
}