(Delphi DLL) JWS Using HMAC SHA-256

Creates a JSON Web Signatures (JWS) using HMAC SHA-256.

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

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, Jws, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
jwsProtHdr: HCkJsonObject;
jws: HCkJws;
hmacKey: PWideChar;
signatureIndex: Integer;
bIncludeBom: Boolean;
payloadStr: PWideChar;
jwsCompact: PWideChar;
jws2: HCkJws;
v: Integer;
joseHeader: HCkJsonObject;

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.

// First create the JWS Protected Header
jwsProtHdr := CkJsonObject_Create();
CkJsonObject_AppendString(jwsProtHdr,'typ','JWT');
CkJsonObject_AppendString(jwsProtHdr,'alg','HS256');
Memo1.Lines.Add('JWS Protected Header: ' + CkJsonObject__emit(jwsProtHdr));

// Output:
// JWS Protected Header: {"typ":"JWT","alg":"HS256"}

jws := CkJws_Create();

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

// Set the protected header:
CkJws_SetProtectedHeader(jws,signatureIndex,jwsProtHdr);

// Set the payload.
bIncludeBom := False;
payloadStr := 'In our village, folks say God crumbles up the old moon into stars.';
CkJws_SetPayload(jws,payloadStr,'utf-8',bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
jwsCompact := CkJws__createJws(jws);
if (CkJws_getLastMethodSuccess(jws) <> True) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;

Memo1.Lines.Add('JWS: ' + jwsCompact);

// sample output:
// JWS: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.bsYsi8HJ0N6OqGI1hKQ9QQRNPxxA5qMpcHLtOvXatk8

// Now load the JWS, validate, and recover the original text.
jws2 := CkJws_Create();

// Load the JWS.
success := CkJws_LoadJws(jws2,jwsCompact);

// Set the MAC key used for validation.
signatureIndex := 0;
CkJws_SetMacKey(jws2,signatureIndex,hmacKey,'base64url');

// Validate the 1st (and only) signature at index 0..
v := CkJws_Validate(jws2,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(CkJws__lastErrorText(jws2));
    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(CkJws__getPayload(jws2,'utf-8'));

// Examine the protected header:
joseHeader := CkJws_GetProtectedHeader(jws2,signatureIndex);
if (CkJws_getLastMethodSuccess(jws2) <> True) then
  begin
    Memo1.Lines.Add('No protected header found at the given index.');
    Exit;
  end;
CkJsonObject_putEmitCompact(joseHeader,False);

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

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	} 

CkJsonObject_Dispose(jwsProtHdr);
CkJws_Dispose(jws);
CkJws_Dispose(jws2);

end;