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Join Date: Jul 2009
Posts: 16
Reputation: Lolalola is an unknown quantity at this point 
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Lolalola Lolalola is offline Offline
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key strength

 
0
  #1
16 Days Ago
Hi,

I'm trying to create a program which provides a key strength. Visual studio don't show errors, but the program hangs on QuadWordFromBigEndian functions. Whats wrong?
Program stop workin on this line:
C# Syntax (Toggle Plain Text) 
  1. 01.x = (           (((UInt64)block[0]) << 56) | (((UInt64)block[1]) << 48) |   
  2. 02.                  (((UInt64)block[2]) << 40) | (((UInt64)block[3]) << 32) |   
  3. 03.                  (((UInt64)block[4]) << 24) | (((UInt64)block[5]) << 16) |   
  4. 04.                  (((UInt64)block[6]) << 8) | ((UInt64)block[7])   
  5. 05.                  );

An show this error:

"Index was outside the bounds of the array."

But I do not know how to fix. What should be the array index.

Thanks


C# Syntax (Toggle Plain Text) 
  1. private void button1_Click(object sender, EventArgs e)
  2.         {
  3.             byte[] sec_key = System.Text.Encoding.UTF8.GetBytes(textBox1.Text);
  4.             if (IsWeakKey(sec_key)) { label1.Text = "Yes"; }
  5.             else { label1.Text = "No"; }
  6.         }
  7.  
  8.         private static bool IsLegalKeySize(byte[] sec_key) { 
  9.             if (sec_key.Length == 8) return(true); 
  10.             return(false); 
  11.         }
  12.  
  13.         private static UInt64 QuadWordFromBigEndian(byte[] block)
  14.         {
  15.             UInt64 x;
  16.             x = (
  17.                   (((UInt64)block[0]) << 56) | (((UInt64)block[1]) << 48) |
  18.                   (((UInt64)block[2]) << 40) | (((UInt64)block[3]) << 32) |
  19.                   (((UInt64)block[4]) << 24) | (((UInt64)block[5]) << 16) |
  20.                   (((UInt64)block[6]) << 8) | ((UInt64)block[7])
  21.                   );
  22.             return (x);
  23.         } 
  24.  
  25.         public static bool IsWeakKey(byte[] sec_key)
  26.         {
  27.  
  28.             UInt64 key = QuadWordFromBigEndian(sec_key);
  29.             if ((key == 0x0101010101010101) ||
  30.                 (key == 0xfefefefefefefefe) ||
  31.                 (key == 0x1f1f1f1f0e0e0e0e) ||
  32.                 (key == 0xe0e0e0e0f1f1f1f1))
  33.             {
  34.                 return (true);
  35.             }
  36.             else
  37.             {
  38.                 return (false);
  39.             }
  40.         }
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Join Date: Oct 2009
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Reputation: thines01 is an unknown quantity at this point 
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thines01 thines01 is offline Offline
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0
  #2
15 Days Ago
Have you ensured the length of the data you're feeding to QuadWordFromBigEndian is 8 (or more) bytes?
...Either by forcing the call to IsLegalKeySize() or by running it in Debug mode with an assert...

C# Syntax (Toggle Plain Text) 
  1. private static UInt64 QuadWordFromBigEndian(byte[] block)
  2.       {
  3.          System.Diagnostics.Debug.Assert(block.Length.Equals(8));
  4.  
  5.          UInt64 x;
  6.          x = (
  7.                (((UInt64)block[0]) << 56) | (((UInt64)block[1]) << 48) |
  8.                (((UInt64)block[2]) << 40) | (((UInt64)block[3]) << 32) |
  9.                (((UInt64)block[4]) << 24) | (((UInt64)block[5]) << 16) |
  10.                (((UInt64)block[6]) << 8)  | ((UInt64)block[7])
  11.                );
  12.  
  13.          return (x);
  14.       }

Then test it with something like this:
C# Syntax (Toggle Plain Text) 
  1. static void Main(string[] args)
  2.       {
  3.          byte[] block = {2,2,2,2,2,2,2,2};
  4.          UInt64 x = QuadWordFromBigEndian(block);
  5.          System.Diagnostics.Trace.WriteLine(x);
  6.       }
Last edited by thines01; 15 Days Ago at 9:50 am. Reason: omission
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Lolalola Lolalola is offline Offline
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0
  #3
15 Days Ago
Thanks, I did not know that the minutes should 8 bytes.

But if I put sec_key = "AAAAbbbb"; and "asdr34bf" i have answer
same. Why?
I sting convert to bytes[]. (byte[] sec_key = System.Text.Encoding.UTF8.GetBytes(textBox1.Text)
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