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POEncrypting a file with 3 passwords
 

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  1. POEncrypting a file with 3 passwords
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    <p>This is kind of an unusual problem. I am having difficulty encrypting a file using 3 passwords. I am attempting to wrap one CryptoStream around two other CryptoStreams, but when I write the file to the disk, it seems to become corrupted, and the padding cannot be completely removed. Why would this be happening?</p> <p>Edit: Here's some sample code</p> <pre><code> public static Stream Encrypt(Stream source, int delcount, params keyPair[] cryptInfo) { Stream prevStream = source; foreach (keyPair et in cryptInfo) { Rijndael mydale = Rijndael.Create(); mydale.BlockSize = 256; mydale.KeySize = 256; mydale.IV = et.IV; mydale.Key = et.key; CryptoStream mystream = new CryptoStream(prevStream, mydale.CreateEncryptor(), CryptoStreamMode.Write); prevStream = mystream; } return prevStream; </code></pre> <p>}</p> <p>Here's the full program Program.cs</p> <pre><code>class Program { static string opcode = "test"; static string IDCID = "an ID"; static string password = "A strong password"; static void Main(string[] args) { if (Console.ReadLine() == "encrypt") { Stream thestream = File.Open(Environment.CurrentDirectory + "\\sample.txt", FileMode.Create, FileAccess.ReadWrite); PasswordDeriveBytes mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(opcode), Encoding.ASCII.GetBytes(opcode)); byte[] key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 15).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 5 + opcode.Length * 24).ToString())); byte[] IV = mybytes.GetBytes(32); keyPair mypair = new GlobalGridCore.keyPair(IV, key); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(password), Encoding.ASCII.GetBytes(password)); key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 9).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 7 + opcode.Length * 24).ToString())); IV = mybytes.GetBytes(32); keyPair secondpair = new keyPair(IV, key); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(IDCID), Encoding.ASCII.GetBytes(IDCID)); key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 2).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 14 + opcode.Length * 7).ToString())); IV = mybytes.GetBytes(32); keyPair thirdpair = new keyPair(IV, key); keyPair[] list = new keyPair[] { mypair, secondpair, thirdpair }; thestream = gridCrypto.Encrypt(thestream, 0, list); BinaryWriter mywriter = new BinaryWriter(thestream); mywriter.Write("ehlo"); mywriter.Write(new byte[512]); mywriter.Flush(); } else { Stream thestream = File.Open(Environment.CurrentDirectory + "\\sample.txt", FileMode.Open, FileAccess.ReadWrite); PasswordDeriveBytes mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(opcode), Encoding.ASCII.GetBytes(opcode)); byte[] key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 15).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 5 + opcode.Length * 24).ToString())); byte[] IV = mybytes.GetBytes(32); keyPair mypair = new GlobalGridCore.keyPair(IV, key); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(password), Encoding.ASCII.GetBytes(password)); key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 9).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 7 + opcode.Length * 24).ToString())); IV = mybytes.GetBytes(32); keyPair secondpair = new keyPair(IV, key); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes(IDCID), Encoding.ASCII.GetBytes(IDCID)); key = mybytes.GetBytes(32); mybytes = new PasswordDeriveBytes(Encoding.Unicode.GetBytes((IDCID.Length + password.Length + opcode.Length * 2).ToString()), Encoding.ASCII.GetBytes((IDCID.Length + password.Length + 14 + opcode.Length * 7).ToString())); IV = mybytes.GetBytes(32); keyPair thirdpair = new keyPair(IV, key); keyPair[] list = new keyPair[] { mypair, secondpair, thirdpair }; thestream = gridCrypto.Decrypt(thestream, list); BinaryReader myreader = new BinaryReader(thestream); Console.WriteLine(myreader.ReadString()); Console.ReadLine(); } } } </code></pre> <p>cryptDriver.cs</p> <pre><code>abstract class gridCrypto { /// &lt;summary&gt; /// Decrypts the input stream to the output stream /// &lt;/summary&gt; /// &lt;param name="source"&gt;I&lt;/param&gt; /// &lt;param name="dest"&gt;O&lt;/param&gt; /// &lt;param name="cryptInfo"&gt;U&lt;/param&gt; public static Stream Decrypt(Stream source, params keyPair[] cryptInfo) { Stream prevStream = source; foreach (keyPair et in cryptInfo) { Rijndael mydale = Rijndael.Create(); mydale.BlockSize = 256; mydale.KeySize = 256; mydale.IV = et.IV; mydale.Key = et.key; CryptoStream mystream = new CryptoStream(prevStream, mydale.CreateDecryptor(), CryptoStreamMode.Read); prevStream = mystream; } return prevStream; } /// &lt;summary&gt; /// Encrypts the input stream and securely deletes the input file with the specified number of passes. The source stream MUST have length /// &lt;/summary&gt; /// &lt;param name="source"&gt;The source stream (to be deleted)&lt;/param&gt; /// &lt;param name="dest"&gt;The destination stream&lt;/param&gt; /// &lt;param name="delcount"&gt;The number of passes to erase the file&lt;/param&gt; /// &lt;param name="cryptInfo"&gt;Crypto stuff&lt;/param&gt; public static Stream Encrypt(Stream source, int delcount, params keyPair[] cryptInfo) { Stream prevStream = source; foreach (keyPair et in cryptInfo) { Rijndael mydale = Rijndael.Create(); mydale.BlockSize = 256; mydale.KeySize = 256; mydale.IV = et.IV; mydale.Key = et.key; CryptoStream mystream = new CryptoStream(prevStream, mydale.CreateEncryptor(), CryptoStreamMode.Write); prevStream = mystream; } return prevStream; //int cpos = 0; //while (cpos &lt; delcount) //{ // source.Position = 0; // while (source.Position &lt; source.Length) // { // if (source.Length - source.Position &gt; 512) // { // Random mrand = new Random(); // byte[] thearray = new byte[512]; // mrand.NextBytes(thearray); // source.Write(thearray, 0, thearray.Length); // } // else // { // Random mrand = new Random(); // byte[] thearray = new byte[source.Length-source.Position]; // mrand.NextBytes(thearray); // source.Write(thearray, 0, thearray.Length); // source.Flush(); // } // } // cpos += 1; //} } } class keyPair { public byte[] IV; public byte[] key; public keyPair(byte[] InitializationVector, byte[] Key) { IV = InitializationVector; key = Key; } } </code></pre> <p>The code to delete the file is commented out and is not used in the program.</p>
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    1. COIt would probably be happening due to a bug in your code. However, you haven't provided any code, so we can't really tell. Please post a short but complete program which demonstrates the problem.
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      1. USJon Skeet
    2. COI added the code. This is the function used to encrypt bytes of data.
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      1. USIDWMaster
    3. CO@IDWMaster: And the code that uses it? And the code that tries to decrypt? A short but complete program would be really useful here...
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      1. POEncrypting a file with 3 passwords
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