(Delphi DLL) 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 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, Cert, CkByteData, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: HCkCrypt2;
cert: HCkCert;
success: Boolean;
detachedSig: HCkByteData;
stringToSign: PWideChar;
verified: Boolean;

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

crypt := CkCrypt2_Create();

cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/cert_test123.pfx','test123');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

// Tell the crypt component to use this cert.
success := CkCrypt2_SetSigningCert(crypt,cert);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

CkCrypt2_putHashAlgorithm(crypt,'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:
CkCrypt2_putIncludeCertChain(crypt,False);

// 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
CkCrypt2_putCharset(crypt,'utf-8');
detachedSig := CkByteData_Create();
stringToSign := '{ "abc": 123}';
success := CkCrypt2_SignString(crypt,stringToSign,detachedSig);
if (CkCrypt2_getLastMethodSuccess(crypt) = False) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

// Verify the signature against the original data.
verified := CkCrypt2_VerifyString(crypt,stringToSign,detachedSig);
if (verified = False) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

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

CkCrypt2_Dispose(crypt);
CkCert_Dispose(cert);
CkByteData_Dispose(detachedSig);

end;