(Delphi ActiveX) Sign JSON (or any Text) to Create a Detached PKCS7 Signature

Demonstrates how to sign JSON or any string using a certificate + private key from a .p12/.pfx to create a detached PKCS7 signature. (A detached signature is one that does not embed the original signed data.)

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;
cert: TChilkatCert;
success: Integer;
detachedSig: Array of Byte;
stringToSign: WideString;
verified: Integer;

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

crypt := TChilkatCrypt2.Create(Self);

cert := TChilkatCert.Create(Self);
success := cert.LoadPfxFile('qa_data/pfx/cert_test123.pfx','test123');
if (success <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

// Tell the crypt component to use this cert.
success := crypt.SetSigningCert(cert.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

crypt.HashAlgorithm := 'sha256';

// By default, all the certs in the chain of authentication are included in the signature.
// If desired, we can choose to only include the signing certificate:
crypt.IncludeCertChain := 0;

// Create the detached signature, which does NOT contain the original data.
// To create a PKCS7 signature that contains the original data, see CAdES Sign JSON
crypt.Charset := 'utf-8';

stringToSign := '{ "abc": 123}';
detachedSig := crypt.SignString(stringToSign);
if (crypt.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Verify the signature against the original data.
verified := crypt.VerifyString(stringToSign,detachedSig);
if (verified = 0) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Success!');
end;