windows phone加密和解密檔案

 private void decryption(string mima)        {            IsolatedStorageFileStream stream = new IsolatedStorageFileStream("aaa.zip加密", FileMode.Open, FileAccess.Read, this.storgfile);            IsolatedStorageFileStream stream2 = new IsolatedStorageFileStream("aaa.zip" + "解密", FileMode.OpenOrCreate, FileAccess.Write, this.storgfile);            byte[] buffer = new byte[100];            long num = 0L;            long length = stream.Length;            string password = mima;            string s = "saltvalue";            byte[] salt = Encoding.UTF8.GetBytes(s);            Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, salt);            this.aes.KeySize = this.aes.LegalKeySizes[0].MaxSize;            this.aes.BlockSize = this.aes.LegalBlockSizes[0].MaxSize;            this.aes.Key = bytes.GetBytes(this.aes.KeySize / 8);            this.aes.IV = bytes.GetBytes(this.aes.BlockSize / 8);            CryptoStream stream3 = new CryptoStream(stream2, this.aes.CreateDecryptor(this.aes.Key, this.aes.IV), CryptoStreamMode.Write);            try            {                try                {                    while (num < length)                    {                        int count = stream.Read(buffer, 0, 100);                        stream3.Write(buffer, 0, count);                        num += count;                    }                    stream3.Close();                }                catch                {                    MessageBox.Show("密碼不正確！無法解密！");                }            }            finally            {                stream.Close();                stream2.Close();            }        }

 private void encryption(string mima)        {            //try            {                IsolatedStorageFileStream stream = new IsolatedStorageFileStream("aaa.zip", FileMode.Open, FileAccess.Read, this.storgfile);                IsolatedStorageFileStream stream2 = new IsolatedStorageFileStream("aaa.zip" + "加密", FileMode.OpenOrCreate, FileAccess.Write, this.storgfile);                byte[] buffer = new byte[100];                long num = 0L;                long length = stream.Length;                string password = mima;                string s = "saltvalue";                byte[] salt = Encoding.UTF8.GetBytes(s);                Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, salt);                this.aes.KeySize = this.aes.LegalKeySizes[0].MaxSize;                this.aes.BlockSize = this.aes.LegalBlockSizes[0].MaxSize;                this.aes.Key = bytes.GetBytes(this.aes.KeySize / 8);                this.aes.IV = bytes.GetBytes(this.aes.BlockSize / 8);                CryptoStream stream3 = new CryptoStream(stream2, this.aes.CreateEncryptor(this.aes.Key, this.aes.IV), CryptoStreamMode.Write);                while (num < length)                {                    int count = stream.Read(buffer, 0, 100);                    stream3.Write(buffer, 0, count);                    num += count;                }                MessageBox.Show("檔案成功加密！");                stream3.Close();                stream.Close();                stream2.Close();            }            //catch            //{            //    MessageBox.Show("沒有將檔案放入指定的IsolatedStore目錄下！");            //}        }