(Delphi ActiveX) Hash a Hex String

Demonstrates common pitfalls in hashing a hex string..

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

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: TChilkatCrypt2;
strToHash: WideString;
hashValue: WideString;

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

crypt := TChilkatCrypt2.Create(Self);

// 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);
Memo1.Lines.Add(crypt.LastErrorText);
Memo1.Lines.Add('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);
Memo1.Lines.Add(crypt.LastErrorText);
Memo1.Lines.Add('hash of 6 hex bytes: ' + hashValue);

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