Delphi ActiveX

Example: Hash Text in Chunks

Shows how to generate a final hash, like SHA-256, for a large text by processing it in chunks. Delphi ActiveX

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
success: Integer;
crypt: TChilkatCrypt2;
bd: TChilkatBinData;
s: WideString;
i: Integer;
encodedHash: WideString;

begin
success := 0;

crypt := TChilkatCrypt2.Create(Self);
crypt.HashAlgorithm := 'sha256';
crypt.Charset := 'utf-8';

bd := TChilkatBinData.Create(Self);

s := 'The quick brown fox jumped over the lazy dog.' + #13#10;

// Accumulate the text in a StringBuilder.  We'll demonstrate hashing the text in chunks,
// and then also hashing the entire text at once to show the results are the same.

bd.AppendString(s,'utf-8');
success := crypt.HashBeginString(s);

i := 0;
while i < 200 do
  begin
    bd.AppendString(s,'utf-8');
    crypt.HashMoreString(s);
    i := i + 1;
  end;

// Get the hash in base64 format.
crypt.EncodingMode := 'base64';

encodedHash := crypt.HashFinalENC();
Memo1.Lines.Add('Hash computed in chunks: ' + encodedHash);

// Let's alternatively compute the hash of the entire amount of data at once,
// to show the hash computation is the same:
encodedHash := crypt.HashBdENC(bd.ControlInterface);
Memo1.Lines.Add('Hash computed in 1 step: ' + encodedHash);

// Output:

// Hash computed in chunks: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
// Hash computed in 1 step: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
end;