Delphi DLL Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-521 SHA-512

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-521 SHA-512 Delphi DLL

var
success: Boolean;
sbPubKey: HCkStringBuilder;
pubKey: HCkPublicKey;
jws: HCkJws;
signatureIndex: Integer;
sbJws: HCkStringBuilder;
v: Integer;
joseHeader: HCkJsonObject;

begin
success := False;

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

//  This example takes a JSON signature in compact serialization format,
//  and uses an ECDSA public key to validate and recover the protected header and payload.

//  We only need a public key for signature validation.  This is the ECDSA public key
//  that is used:

//       {"kty":"EC", 
//        "crv":"P-521", 
//        "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk", 
//        "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2" 
//       } 

sbPubKey := CkStringBuilder_Create();
CkStringBuilder_Append(sbPubKey,'{"kty":"EC",');
CkStringBuilder_Append(sbPubKey,'"crv":"P-521",');
CkStringBuilder_Append(sbPubKey,'"x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk",');
CkStringBuilder_Append(sbPubKey,'"y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2"');
CkStringBuilder_Append(sbPubKey,'}');

pubKey := CkPublicKey_Create();
success := CkPublicKey_LoadFromString(pubKey,CkStringBuilder__getAsString(sbPubKey));
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

jws := CkJws_Create();

//  Set the ECC public key:
signatureIndex := 0;
CkJws_SetPublicKey(jws,signatureIndex,pubKey);

//  Load the JWS.
sbJws := CkStringBuilder_Create();
CkStringBuilder_Append(sbJws,'eyJhbGciOiJFUzUxMiJ9');
CkStringBuilder_Append(sbJws,'.');
CkStringBuilder_Append(sbJws,'UGF5bG9hZA');
CkStringBuilder_Append(sbJws,'.');
CkStringBuilder_Append(sbJws,'AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq');
CkStringBuilder_Append(sbJws,'wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp');
CkStringBuilder_Append(sbJws,'EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn');

success := CkJws_LoadJwsSb(jws,sbJws);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;

//  Validate the 1st (and only) signature at index 0..
v := CkJws_Validate(jws,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(jws));
    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.');
Memo1.Lines.Add('--');

//  Recover the original content:
Memo1.Lines.Add('Recovered content:');
Memo1.Lines.Add(CkJws__getPayload(jws,'utf-8'));
Memo1.Lines.Add('--');

//  Examine the protected header:

joseHeader := CkJsonObject_Create();
success := CkJws_GetProtectedH(jws,signatureIndex,joseHeader);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    Exit;
  end;

CkJsonObject_putEmitCompact(joseHeader,False);

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

//  Output:
//  (the string "Payload" was the content that was signed.)

//  	Signature validated.
//  	--
//  	Recovered content:
//  	Payload
//  	--
//  	Protected (JOSE) header:
//  	{
//  	  "alg": "ES512"
//  	}

CkStringBuilder_Dispose(sbPubKey);
CkPublicKey_Dispose(pubKey);
CkJws_Dispose(jws);
CkStringBuilder_Dispose(sbJws);
CkJsonObject_Dispose(joseHeader);