(Delphi ActiveX) Verify JWT with EdDSA / Ed25519 Signature

Note: This example requires Chilkat v9.5.0.84 or greater.

Demonstrates how to verify a JWT that was signed using an Ed25519 private key.

This example verifies the EdDSA signature. It also does the following:

• Checks to see if the time constraints ("nbf" and "exp") are valid.
• Recovers the original JOSE header.
• Recovers the original 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
jsonPubKey: WideString;
pubKey: TPublicKey;
success: Integer;
jwt: TChilkatJwt;
token: WideString;
sigVerified: Integer;
leeway: Integer;
bTimeValid: Integer;
payload: WideString;
joseHeader: WideString;

begin
// Demonstrates how to verify a JWT with an EdDSA/Ed25519 Signature
// *** Requires Chilkat v9.5.0.84 or greater.

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

// Use this Ed25519 public key for verification

jsonPubKey := '{"kty": "OKP","alg": "EdDSA","crv": "Ed25519","x": "11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo"}';

pubKey := TPublicKey.Create(Self);
success := pubKey.LoadFromString(jsonPubKey);
if (success = 0) then
  begin
    Memo1.Lines.Add(pubKey.LastErrorText);
    Exit;
  end;

jwt := TChilkatJwt.Create(Self);
token := 'eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg';

// First verify the signature.
sigVerified := jwt.VerifyJwtPk(token,pubKey.ControlInterface);
Memo1.Lines.Add('verified: ' + IntToStr(Ord(sigVerified)));

if (sigVerified = 0) then
  begin
    Memo1.Lines.Add(jwt.LastErrorText);
    Exit;
  end;

// Let's see if the time constraints, if any, are valid.
// The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
// If the current system time is before the "nbf" time, or after the "exp" time,
// then IsTimeValid will return false/0.
// Also, we'll allow a leeway of 60 seconds to account for any clock skew.
// Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
leeway := 60;
bTimeValid := jwt.IsTimeValid(token,leeway);
Memo1.Lines.Add('time constraints valid: ' + IntToStr(Ord(bTimeValid)));

// Recover the original data (the payload).
payload := jwt.GetPayload(token);
Memo1.Lines.Add(payload);

// Recover the original JOSE header in the same way:
joseHeader := jwt.GetHeader(token);
Memo1.Lines.Add(joseHeader);
end;