Delphi DLL

CMS Sign Hash

Demonstrates how to use the SignHashENC method to sign a pre-computed hash. This method creates a CMS signature (PKCS7 detached signature).

This example requires Chilkat v9.5.0.90 or later.

Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
crypt: HCkCrypt2;
base64Hash: PWideChar;
cert: HCkCert;
base64CmsSig: PWideChar;

begin
success := False;

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

crypt := CkCrypt2_Create();

// Create the hash to be signed...
CkCrypt2_putHashAlgorithm(crypt,'sha256');
CkCrypt2_putEncodingMode(crypt,'base64');
CkCrypt2_putCharset(crypt,'utf-8');
// Create the SHA256 hash of a string using the utf-8 byte representation.
// Return the hash as base64.
base64Hash := CkCrypt2__hashStringENC(crypt,'This is the string to be hashed');

// Load a certificate for signing.
cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/cert_test123.pfx','test123');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;
CkCrypt2_SetSigningCert(crypt,cert);

// Sign the hash to create a base64 CMS signature (which does not contain the original data).
// We can get the signature in a single line of base64 by specifying "base64", or 
// we can get multi-line base64 by specifying "base64_mime".
CkCrypt2_putEncodingMode(crypt,'base64_mime');
base64CmsSig := CkCrypt2__signHashENC(crypt,base64Hash,'sha256','base64');
if (CkCrypt2_getLastMethodSuccess(crypt) = False) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

// Note: In the above call to SignHashENC, the encoding of the returned CMS signature is specified by the EncodingMode property.
// However, the encoding of the passed-in hash is indicated by the 3rd argument.

Memo1.Lines.Add('CMS Signature: ' + base64CmsSig);

CkCrypt2_Dispose(crypt);
CkCert_Dispose(cert);

end;