(Delphi ActiveX) Create a JWS Using ECDSA P-256 SHA-256

Creates and validates a JSON Web Signature (JWS) that uses ECDSA P-256 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
sbJwk: TChilkatStringBuilder;
eccKey: TPrivateKey;
success: Integer;
jwsProtHdr: TChilkatJsonObject;
jws: TChilkatJws;
signatureIndex: Integer;
bIncludeBom: Integer;
payloadStr: WideString;
jwsCompact: WideString;
jws2: TChilkatJws;
eccPubKey: IPublicKey;
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.

// Use the following ECC key loaded from JWK format.
sbJwk := TChilkatStringBuilder.Create(Self);
sbJwk.Append('{"kty":"EC",');
sbJwk.Append('"crv":"P-256",');
sbJwk.Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",');
sbJwk.Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",');
sbJwk.Append('"d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"');
sbJwk.Append('}');

eccKey := TPrivateKey.Create(Self);
// Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
// into the private key object. (See the online reference documentation..)
success := eccKey.LoadJwk(sbJwk.GetAsString());
if (success <> 1) then
  begin
    Memo1.Lines.Add(eccKey.LastErrorText);
    Exit;
  end;

// Create the JWS Protected Header
jwsProtHdr := TChilkatJsonObject.Create(Self);
jwsProtHdr.AppendString('alg','ES256');

jws := TChilkatJws.Create(Self);

// Set the protected header:
signatureIndex := 0;
jws.SetProtectedHeader(signatureIndex,jwsProtHdr.ControlInterface);

// Set the ECC key:
jws.SetPrivateKey(signatureIndex,eccKey.ControlInterface);

// Set the payload.
bIncludeBom := 0;
payloadStr := 'In our village, folks say God crumbles up the old moon into stars.';
jws.SetPayload(payloadStr,'utf-8',bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
jwsCompact := jws.CreateJws();
if (jws.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(jws.LastErrorText);
    Exit;
  end;

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

// Note: ECC signatures use random values, so the output will be different each time a signature is produced.
// sample output:
// JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

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

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

eccPubKey := eccKey.GetPublicKey();

// Set the ECC public key used for validation.
signatureIndex := 0;
jws2.SetPublicKey(signatureIndex,eccPubKey);

// Validate the 1st (and only) signature at index 0..
v := jws2.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(jws2.LastErrorText);
    Exit;
  end;
if (v = 0) then
  begin
    Memo1.Lines.Add('Invalid signature.  The ECC 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(jws2.GetPayload('utf-8'));

// Examine the protected header:
joseHeader := jws2.GetProtectedHeader(signatureIndex);
if (jws2.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.
// In our village, folks say God crumbles up the old moon into stars.
// Protected (JOSE) header:
// { 
//   "alg": "ES256"
// }
end;