Encryption

Hi,

Iam using the following code for encrypting some text and save it to a text file:

  // Open a local file on the C drive.
FileStream fs = new FileStream(@"MyData.txt", FileMode.Open);
//Now generate a hash code for this file using MD5.
HashAlgorithm alg = HashAlgorithm.Create("MD5");
byte[] fileHashValue = alg.ComputeHash(fs);

// Print out the generated hash code.
fs.Close();

File.WriteAllText("MyData.txt",fileHashValue);

 
I want to save to the same text file the same data decrypted through another button.How could I retreive the hashed data

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