(Delphi ActiveX) Validate JWS Using HMAC SHA-256

Validates a JSON Web Signature (JWS) using HMAC SHA-256.

Note: This example requires Chilkat v9.5.0.66 or greater.

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
jws: TChilkatJws;
hmacKey: WideString;
signatureIndex: Integer;
jwsCompact: WideString;
success: Integer;
v: Integer;
joseHeader: IChilkatJsonObject;

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

// Note: This example requires Chilkat v9.5.0.66 or greater.

// This example takes a JSON signature in compact serialization format,
// and uses a MAC key to validate and recover the protected header and payload.

jws := TChilkatJws.Create(Self);

// Set the HMAC key:
hmacKey := 'AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow';
signatureIndex := 0;
jws.SetMacKey(signatureIndex,hmacKey,'base64url');

// Load the JWS.
jwsCompact := 'eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk';
success := jws.LoadJws(jwsCompact);

// Validate the 1st (and only) signature at index 0..
v := jws.Validate(signatureIndex);
if (v < 0) then
  begin
    // Perhaps Chilkat was not unlocked or the trial expired..
    Memo1.Lines.Add('Method call failed for some other reason.');
    Memo1.Lines.Add(jws.LastErrorText);
    Exit;
  end;
if (v = 0) then
  begin
    Memo1.Lines.Add('Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.');
    Exit;
  end;

// If we get here, the signature was validated..
Memo1.Lines.Add('Signature validated.');

// Recover the original content:
Memo1.Lines.Add('Recovered content:');
Memo1.Lines.Add(jws.GetPayload('utf-8'));

// Examine the protected header:
joseHeader := jws.GetProtectedHeader(signatureIndex);
if (jws.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add('No protected header found at the given index.');
    Exit;
  end;
joseHeader.EmitCompact := 0;

Memo1.Lines.Add('Protected (JOSE) header:');
Memo1.Lines.Add(joseHeader.Emit());

// Output:

// 	Signature validated.
// 	Recovered content:
// 	{"iss":"joe",
// 	 "exp":1300819380,
// 	 "http://example.com/is_root":true}
// 	Protected (JOSE) header:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	}
end;