(Delphi DLL) 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 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, StringBuilder, PrivateKey, Jws, PublicKey, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
sbJwk: HCkStringBuilder;
eccKey: HCkPrivateKey;
success: Boolean;
jwsProtHdr: HCkJsonObject;
jws: HCkJws;
signatureIndex: Integer;
bIncludeBom: Boolean;
payloadStr: PWideChar;
jwsCompact: PWideChar;
jws2: HCkJws;
eccPubKey: HCkPublicKey;
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.

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

eccKey := CkPrivateKey_Create();
// 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 := CkPrivateKey_LoadJwk(eccKey,CkStringBuilder__getAsString(sbJwk));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(eccKey));
    Exit;
  end;

// Create the JWS Protected Header
jwsProtHdr := CkJsonObject_Create();
CkJsonObject_AppendString(jwsProtHdr,'alg','ES256');

jws := CkJws_Create();

// Set the protected header:
signatureIndex := 0;
CkJws_SetProtectedHeader(jws,signatureIndex,jwsProtHdr);

// Set the ECC key:
CkJws_SetPrivateKey(jws,signatureIndex,eccKey);

// 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);

// 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 := CkJws_Create();

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

eccPubKey := CkPrivateKey_GetPublicKey(eccKey);

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

// 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 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(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:
// { 
//   "alg": "ES256"
// }

CkStringBuilder_Dispose(sbJwk);
CkPrivateKey_Dispose(eccKey);
CkJsonObject_Dispose(jwsProtHdr);
CkJws_Dispose(jws);
CkJws_Dispose(jws2);

end;