Pascal (Lazarus/Delphi)

Hash a Hex String

See more Encryption Examples

Demonstrates common pitfalls in hashing a hex string..

Note: This example requires Chilkat v9.5.0.70 or greater.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Crypt2;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  crypt: TCrypt2;
  strToHash: string;
  hashValue: string;

begin
  //  This example assumes the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  crypt := TCrypt2.Create;

  //  We have a hex string to be SHA-256 hashed:  "b08538d832bf"
  //  The result we expect to receive is "8a9f04cb1adfbd7f59c5918635f92f6c847e5b15f9828519d2fdbd6ead0918fc"

  strToHash := 'b08538d832bf';

  //  How do we get this result?

  //  The 1st question to be answered is:  What bytes are getting hashed?  
  //  There are two possibilities:
  //  1) Hash 12 bytes, namely the us-ascii values for 'b', '0', '8', '5', .... 'b', 'f'
  //  or
  //  2) Hash 6 bytes:  0xb0, 0x85, ... 0xbf
  //  

  //  This is how to hash the 12 us-ascii byte values:
  //  The Charset property defines the byte representation of the string passed to the hash algorithm:
  crypt.Charset := 'us-ascii';
  //  The EncodingMode property defines the binary encoding (hex, base64, etc.) of the hash returned as an encoded string.
  crypt.EncodingMode := 'hex';
  crypt.HashAlgorithm := 'sha256';

  hashValue := crypt.HashStringENC(strToHash);
  WriteLn(crypt.LastErrorText);
  WriteLn('hash of 12 us-ascii bytes: ' + hashValue);

  //  The result is:  327F2B33A0F0580D09840B0D7CEE54514CA33E9A  (not what we were hoping).

  //  -------------------------------------------
  //  This is how to hash the 6 bytes
  //  
  //  "hex" is not an actual character encoding.  It's a special value to be used to tell Chilkat to hex decode
  //  the string and pass the decoded bytes to the hash algorithm...
  //  Note: This example requires Chilkat v9.5.0.70 or greater for the "hex" Charset to work properly.
  crypt.Charset := 'hex';
  //  The EncodingMode and HashAlgorithm remain the same..
  hashValue := crypt.HashStringENC(strToHash);
  WriteLn(crypt.LastErrorText);
  WriteLn('hash of 6 hex bytes: ' + hashValue);

  //  The result is 8A9F04CB1ADFBD7F59C5918635F92F6C847E5B15F9828519D2FDBD6EAD0918FC (which equals the hash we were expecting)


  crypt.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.