(Delphi DLL) Example: Hash Text in Chunks

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

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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: HCkCrypt2;
bd: HCkBinData;
s: PWideChar;
success: Boolean;
i: Integer;
encodedHash: PWideChar;

begin
crypt := CkCrypt2_Create();
CkCrypt2_putHashAlgorithm(crypt,'sha256');
CkCrypt2_putCharset(crypt,'utf-8');

bd := CkBinData_Create();

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.

CkBinData_AppendString(bd,s,'utf-8');
success := CkCrypt2_HashBeginString(crypt,s);

i := 0;
while i < 200 do
  begin
    CkBinData_AppendString(bd,s,'utf-8');
    CkCrypt2_HashMoreString(crypt,s);
    i := i + 1;
  end;

// Get the hash in base64 format.
CkCrypt2_putEncodingMode(crypt,'base64');

encodedHash := CkCrypt2__hashFinalENC(crypt);
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 := CkCrypt2__hashBdENC(crypt,bd);
Memo1.Lines.Add('Hash computed in 1 step: ' + encodedHash);

// Output:

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

CkCrypt2_Dispose(crypt);
CkBinData_Dispose(bd);

end;