hi all thanks in advance.......anybody working in encryption and decryption in salesforce and other dotnet external application :
 
apexclass:
public with sharing class Security {
  /*
    key length depends of ALGORITHM_NAME! 
    In case, it uses AES256 so we need to use 32 bytes key must.
  */    
  public static final String MY_KEY = '12345678901234567890123456789012'; // it always must  be 32bytes 
  public static final String MY_IV = 'HR$2pIjHR$2pIj12'; //it always will be 16 bytes
  public static final String ALGORITHM_NAME = 'AES256';
  public static Blob encrypt(String valueToEncrypt){
    Blob key = Blob.valueOf(MY_KEY);
    Blob iv = Blob.valueOf(MY_IV);
    Blob data = Blob.valueOf(valueToEncrypt);
    return Crypto.encrypt(ALGORITHM_NAME, key, iv, data);
  }
  public static Blob decrypt(Blob encryptedData){
    Blob key = Blob.valueOf(MY_KEY);
    Blob iv = Blob.valueOf(MY_IV);
    return Crypto.decrypt(ALGORITHM_NAME, key, iv, encryptedData);
  }
   
}
 
//--------------open the anonymous window in developer console-----------------------//
Blob encryptedData = Security.encrypt('India');
String base64Data = EncodingUtil.base64Encode(encryptedData);
System.debug('encryptedData: ' + base64Data);
System.debug('iv: ' + EncodingUtil.base64Encode(Blob.valueOf(Security.MY_IV)));
System.debug('key: ' + EncodingUtil.base64Encode(Blob.valueOf(Security.MY_KEY)));
Blob decryptedData = Security.decrypt(encryptedData);
System.debug('decryptedData: ' + decryptedData.toString());
 
 
//------------------------requirement is here------------------------//
We have used a salesforce method  key sizeof AES256 and keyvalue as '12345678901234567890123456789012'  32bytes for encrypting the login credentials
But in .net application for encrypting, they have used keysize of AES256 and keyvalue as “MARKETING” which is 9bytes.
we had used the same keyvalue“MARKETING”,for encryption but it is showing an error that keyvalue must be of 32bytes..
 
 
 
AFTER ENCRYPTION INDIA THE ENCRPTED VALUE SHOULD BE :
k+aPFgavOKqygOIsLhf8EQ==
For 'India'
 
////////////////////----dotnet code as shown below----//////////////////
private static string Salt = "MarketingInc";
        private static string HashAlgorithm = "SHA1";
        private static int PasswordIterations = 2;
        private static string InitialVector = "HR$2pIjHR$2pIj12";
        private static int KeySize = 256;
 
 
public static string EncryptText(string toBeEncrypted, string password)
        {
            string result;
            try
            {
                if (string.IsNullOrEmpty(toBeEncrypted))
                {
                    result = "";
                }
                else
                {
                    byte[] bytes = System.Text.Encoding.UTF8.GetBytes(toBeEncrypted);
                    byte[] bytes2 = System.Text.Encoding.UTF8.GetBytes(password);
                    byte[] inArray = EncryptDecrypt.AES_Encrypt(bytes, bytes2);
                    string text = System.Convert.ToBase64String(inArray);
                    result = text;
                }
            }
            catch (System.Exception)
            {
                result = "";
            }
            return result;
        }
        public static string DecryptText(string toBeDecrypted, string password)
        {
            string result;
            try
            {
                if (string.IsNullOrEmpty(toBeDecrypted))
                {
                    result = "";
                }
                else
                {
                    byte[] cipherTextBytes = System.Convert.FromBase64String(toBeDecrypted);
                    byte[] bytes = System.Text.Encoding.UTF8.GetBytes(password);
                    byte[] bytes2 = EncryptDecrypt.AES_Decrypt(cipherTextBytes, bytes);
                    string @string = System.Text.Encoding.UTF8.GetString(bytes2);
                    result = @string;
                }
            }
            catch (System.Exception)
            {
                result = "";
            }
            return result;
        }


solve the problem