双向AES加密

我正在使用一个在这里找到的类来进行AES加密/解密。它对我来说确实工作正常，但当我使用EncryptToString方法加密字符串时，加密只包含数字。我希望它包含数字、字母和符号。你知道为什么它只包含数字吗？感谢

这是我所指的代码：

 public class AESEncryption
{
    // These can be anything I desire but must be less than or equal to 255
    private byte[] Key = { 222, 237, 16, 14, 28, 26, 85, 45, 114, 184, 27, 192, 37, 112, 222, 209, 241, 24, 175, 144, 173, 53, 105, 29, 24, 26, 17, 218, 131, 236, 53, 209 };
    private byte[] Vector = { 146, 64, 101, 111, 23, 32, 113, 119, 231, 121, 211, 11, 99, 32, 104, 156 };

    private ICryptoTransform EncryptorTransform, DecryptorTransform;
    private System.Text.UTF8Encoding UTFEncoder;
    public AESEncryption()
    {
        //This is our encryption method 
        RijndaelManaged rm = new RijndaelManaged();
        //Create an encryptor and a decryptor using our encryption method, key, and vector. 
        EncryptorTransform = rm.CreateEncryptor(this.Key, this.Vector);
        DecryptorTransform = rm.CreateDecryptor(this.Key, this.Vector);
        //Used to translate bytes to text and vice versa 
        UTFEncoder = new System.Text.UTF8Encoding();
    }
    /// -------------- Two Utility Methods (not used but may be useful) ----------- 
    /// Generates an encryption key. 
    static public byte[] GenerateEncryptionKey()
    {
        //Generate a Key. 
        RijndaelManaged rm = new RijndaelManaged();
        rm.GenerateKey();
        return rm.Key;
    }
    /// Generates a unique encryption vector 
    static public byte[] GenerateEncryptionVector()
    {
        //Generate a Vector 
        RijndaelManaged rm = new RijndaelManaged();
        rm.GenerateIV();
        return rm.IV;
    }

    /// ----------- The commonly used methods ------------------------------     
    /// Encrypt some text and return a string suitable for passing in a URL. 
    public string EncryptToString(string TextValue)
    {
        return ByteArrToString(Encrypt(TextValue));
    }
    /// Encrypt some text and return an encrypted byte array. 
    public byte[] Encrypt(string TextValue)
    {
        //Translates our text value into a byte array. 
        Byte[] bytes = UTFEncoder.GetBytes(TextValue);
        //Used to stream the data in and out of the CryptoStream. 
        MemoryStream memoryStream = new MemoryStream();
        /* 
         * We will have to write the unencrypted bytes to the stream, 
         * then read the encrypted result back from the stream. 
         */
        #region Write the decrypted value to the encryption stream
        CryptoStream cs = new CryptoStream(memoryStream, EncryptorTransform, CryptoStreamMode.Write);
        cs.Write(bytes, 0, bytes.Length);
        cs.FlushFinalBlock();
        #endregion
        #region Read encrypted value back out of the stream
        memoryStream.Position = 0;
        byte[] encrypted = new byte[memoryStream.Length];
        memoryStream.Read(encrypted, 0, encrypted.Length);
        #endregion
        //Clean up. 
        cs.Close();
        memoryStream.Close();
        return encrypted;
    }
    /// The other side: Decryption methods 
    public string DecryptString(string EncryptedString)
    {
        return Decrypt(StrToByteArray(EncryptedString));
    }
    /// Decryption when working with byte arrays.     
    public string Decrypt(byte[] EncryptedValue)
    {
        #region Write the encrypted value to the decryption stream
        MemoryStream encryptedStream = new MemoryStream();
        CryptoStream decryptStream = new CryptoStream(encryptedStream, DecryptorTransform, CryptoStreamMode.Write);
        decryptStream.Write(EncryptedValue, 0, EncryptedValue.Length);
        decryptStream.FlushFinalBlock();
        #endregion
        #region Read the decrypted value from the stream.
        encryptedStream.Position = 0;
        Byte[] decryptedBytes = new Byte[encryptedStream.Length];
        encryptedStream.Read(decryptedBytes, 0, decryptedBytes.Length);
        encryptedStream.Close();
        #endregion
        return UTFEncoder.GetString(decryptedBytes);
    }
    /// Convert a string to a byte array.  NOTE: Normally we'd create a Byte Array from a string using an ASCII encoding (like so). 
    //      System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); 
    //      return encoding.GetBytes(str); 
    // However, this results in character values that cannot be passed in a URL.  So, instead, I just 
    // lay out all of the byte values in a long string of numbers (three per - must pad numbers less than 100). 
    public byte[] StrToByteArray(string str)
    {
        if (str.Length == 0)
            throw new Exception("Invalid string value in StrToByteArray");
        byte val;
        byte[] byteArr = new byte[str.Length / 3];
        int i = 0;
        int j = 0;
        do
        {
            val = byte.Parse(str.Substring(i, 3));
            byteArr[j++] = val;
            i += 3;
        }
        while (i < str.Length);
        return byteArr;
    }
    // Same comment as above.  Normally the conversion would use an ASCII encoding in the other direction: 
    //      System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); 
    //      return enc.GetString(byteArr);     
    public string ByteArrToString(byte[] byteArr)
    {
        byte val;
        string tempStr = "";
        for (int i = 0; i <= byteArr.GetUpperBound(0); i++)
        {
            val = byteArr[i];
            if (val < (byte)10)
                tempStr += "00" + val.ToString();
            else if (val < (byte)100)
                tempStr += "0" + val.ToString();
            else
                tempStr += val.ToString();
        }
        return tempStr;
    }
}

/// Convert a string to a byte array.  NOTE: Normally we'd create a Byte Array from a string using an ASCII encoding (like so). 
//      System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); 
//      return encoding.GetBytes(str); 
// However, this results in character values that cannot be passed in a URL.  So, instead, I just 
// lay out all of the byte values in a long string of numbers (three per - must pad numbers less than 100). 
public byte[] StrToByteArray(string str)

// Same comment as above.  Normally the conversion would use an ASCII encoding in the other direction: 
//      System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); 
//      return enc.GetString(byteArr);     
public string ByteArrToString(byte[] byteArr)

//Translates our text value into a byte array.
Byte[] bytes = UTFEncoder.GetBytes(TextValue);

File.WriteAllBytes("C:'MyTestFile.txt", Encrypt("My Clear Text"));

return UTFEncoder.GetString(decryptedBytes);