Security C#

using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace OpusSuite.Utility
{
    public static class CryptoUtil
    {
       private static byte[] _salt = Encoding.ASCII.GetBytes("o6806642kbM7c5");      
   
        public static string EncryptStringAES(string plainText, string sharedSecret)     
        {         
            if(string.IsNullOrEmpty(plainText))             
                throw new ArgumentNullException("plainText");         
            if(string.IsNullOrEmpty(sharedSecret))             
                throw new ArgumentNullException("sharedSecret");          
            string outStr = null;                       // Encrypted string to return         
            RijndaelManaged aesAlg = null;              // RijndaelManaged object used to encrypt the data.
            try         
            {             
                // generate the key from the shared secret and the salt             
                var key = new Rfc2898DeriveBytes(sharedSecret, _salt);              
                // Create a RijndaelManaged object             
                // with the specified key and IV.             
                aesAlg = new RijndaelManaged();             
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);             
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);              
                // Create a decrytor to perform the stream transform.             
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);              
                // Create the streams used for encryption.             
                using (var msEncrypt = new MemoryStream())             
                {                 
                    using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {                     
                        using (var swEncrypt = new StreamWriter(csEncrypt))                     
                        {                          
                            //Write all data to the stream.                         
                            swEncrypt.Write(plainText);                     
                        }                 
                    }                 
                    outStr = Convert.ToBase64String(msEncrypt.ToArray());             
                }         
            }         
            finally         
            {             
                // Clear the RijndaelManaged object.             
                if (aesAlg != null)                 
                    aesAlg.Clear();         
            }          
            // Return the encrypted bytes from the memory stream.         
            return outStr;     
        }      
        
        public static string DecryptStringAES(string cipherText, string sharedSecret)     
        {         
            if (string.IsNullOrEmpty(cipherText))             
                throw new ArgumentNullException("cipherText");         
            if (string.IsNullOrEmpty(sharedSecret))             
                throw new ArgumentNullException("sharedSecret");          
            // Declare the RijndaelManaged object         
            // used to decrypt the data.         
            RijndaelManaged aesAlg = null;          
            // Declare the string used to hold         
            // the decrypted text.         
            string plaintext = null;          
            try         
            {             
                // generate the key from the shared secret and the salt             
                var key = new Rfc2898DeriveBytes(sharedSecret, _salt);              
                // Create a RijndaelManaged object             
                // with the specified key and IV.             
                aesAlg = new RijndaelManaged();             
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);              
                // Create a decrytor to perform the stream transform.             
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
                // Create the streams used for decryption.                             
                byte[] bytes = Convert.FromBase64String(cipherText);             
                using (var msDecrypt = new MemoryStream(bytes))             
                {                 
                    using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))                 
                    {                     
                        using (var srDecrypt = new StreamReader(csDecrypt))                          
                            // Read the decrypted bytes from the decrypting stream                         
                            // and place them in a string.                         
                            plaintext = srDecrypt.ReadToEnd();                 
                    }             
                }         
            }         
            finally         
            {             
                // Clear the RijndaelManaged object.             
                if (aesAlg != null)                 
                    aesAlg.Clear();         
            }          
            return plaintext;     
        } 
    } 
}