Index was outside the bounds of the array

Question

Hi,

 

I'm trying to encrypt a field in my local database table using my own algorithm. encryption is done well. but decryption produces to me an exception error

 

Exception thrown: 'System.IndexOutOfRangeException'

 

my code is

private void button10_Click(object sender, EventArgs e)
{
OracleConnection conn;
String VtextKey = this.txtKey.Text;
using (conn = new OracleConnection(oradb))
{
OracleCommand select = new OracleCommand("select empno,ENAME,job from emp", conn);
conn.Open();
OracleDataReader reader = select.ExecuteReader();
Int64 vempno = 0;
String EnameValue = "";
String jobValue = "";
String DecryptEname = "";
String Decryptjob = "";
if (reader.HasRows)
{
while (reader.Read())
{
vempno = reader.GetInt64(0);
EnameValue = reader.GetString(1);
jobValue = reader.GetString(2);
Enigma enigma = new Enigma();
DecryptEname = enigma.Decrypt(EnameValue, VtextKey);
OracleCommand update = new OracleCommand("update emp set ename =:fname, job =:job where empno =:empno", conn);
OracleParameter ename = new OracleParameter("ename", DecryptEname);
OracleParameter job = new OracleParameter("job", Decryptjob);
OracleParameter empno = new OracleParameter("empno", vempno);
update.Parameters.Add(ename);
update.Parameters.Add(job);
update.Parameters.Add(empno);
update.ExecuteNonQuery();
}
MessageBox.Show("User updated!");
OracleDataAdapter a = new OracleDataAdapter("SELECT * FROM emp", conn);
DataTable t = new DataTable();
a.Fill(t);
dataGridView1.DataSource = t;
reader.Close();
}
}
}
and the exception error is on this line
PlainBytes[i / 2] = (byte)(((Cipher ^ ((Left) ? LeftHash[Mapping] : RightHash[Mapping]))));
this is the decryption function
public String Decrypt(String EncryptedText, String Key)
{
String PlainText = "";
Byte[] PlainBytes = new Byte[CipherText.Length / 2];
MD5 HashGenerator = MD5.Create();
Byte[] KeyHashBytes = HashGenerator.ComputeHash(Encoding.UTF8.GetBytes(Key));
StringBuilder Builder = new StringBuilder();
for (int i = 0; i < KeyHashBytes.Length; i++)
{
Builder.Append(KeyHashBytes[i].ToString("x2"));
}
String KeyHashString = Builder.ToString();
String[] KeyHashChunks = new String[2];
KeyHashChunks[0] = KeyHashString.Substring(0, 16);
KeyHashChunks[1] = KeyHashString.Substring(16);
Byte[] LeftHash = Encoding.ASCII.GetBytes(KeyHashChunks[0]);
Byte[] RightHash = Encoding.ASCII.GetBytes(KeyHashChunks[1]);
Byte[] EncryptedBytes = Encoding.ASCII.GetBytes(EncryptedText);
for (int i = 0; i < (EncryptedBytes.Length-1); i += 2)
{
Byte Cipher = EncryptedBytes[i];
Byte Meta = EncryptedBytes[i + 1];
Meta = (byte)((int)Meta - 33);
Cipher = (byte)((int)Cipher - 33);
int Remains = ((int)Meta > 32) ? 1 : 0;
Meta = (Remains == 1) ? (byte)((int)Meta - 32) : Meta;
Boolean Left = ((int)Meta > 16) ? false : true;
Meta = (Left) ? Meta : (byte)((int)Meta - 16);
int Mapping = (int)Meta;
Cipher = (byte)(((int)Cipher * 2) + Remains);
PlainBytes[i / 2] = (byte)(((Cipher ^ ((Left) ? LeftHash[Mapping] : RightHash[Mapping]))));
}
PlainText = Encoding.ASCII.GetString(PlainBytes);
return PlainText;
}