Pascal (Lazarus/Delphi)

Verify JWT with EdDSA / Ed25519 Signature

See more JSON Web Token (JWT) Examples

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.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Jwt,
  Chilkat.PublicKey;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  jsonPubKey: string;
  pubKey: TPublicKey;
  jwt: TJwt;
  token: string;
  sigVerified: Boolean;
  leeway: Integer;
  bTimeValid: Boolean;
  payload: string;
  joseHeader: string;

begin
  success := False;

  //  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;
  success := pubKey.LoadFromString(jsonPubKey);
  if (success = False) then
    begin
      WriteLn(pubKey.LastErrorText);
      Exit;
    end;

  jwt := TJwt.Create;
  token := 'eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg';

  //  First verify the signature.
  sigVerified := jwt.VerifyJwtPk(token,pubKey);
  WriteLn('verified: ' + sigVerified);

  if (sigVerified = False) then
    begin
      WriteLn(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);
  WriteLn('time constraints valid: ' + bTimeValid);

  //  Recover the original data (the payload).
  payload := jwt.GetPayload(token);
  WriteLn(payload);

  //  Recover the original JOSE header in the same way:
  joseHeader := jwt.GetHeader(token);
  WriteLn(joseHeader);


  pubKey.Free;
  jwt.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.