(Delphi DLL) Compute JWK Thumbprint for RSA and EC Public Keys

Demonstrates how to compute a JSON Web Key thumbprint for a public key (RSA or ECC).

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, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
pubKey: HCkPublicKey;
sb: HCkStringBuilder;
success: Boolean;

begin
pubKey := CkPublicKey_Create();

// A public key can be loaded from any format (binary DER, PEM, etc.)
// This example will load the public keys from JWK format, 
// and will then compute the JWK thumbprint.

// First do it for an RSA public key...

sb := CkStringBuilder_Create();
CkStringBuilder_Append(sb,'{');
CkStringBuilder_Append(sb,'"kty": "RSA",');
CkStringBuilder_Append(sb,'"n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAt');
CkStringBuilder_Append(sb,'VT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn6');
CkStringBuilder_Append(sb,'4tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FD');
CkStringBuilder_Append(sb,'W2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n9');
CkStringBuilder_Append(sb,'1CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINH');
CkStringBuilder_Append(sb,'aQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",');
CkStringBuilder_Append(sb,'"e": "AQAB",');
CkStringBuilder_Append(sb,'"alg": "RS256",');
CkStringBuilder_Append(sb,'"kid": "2011-04-29"');
CkStringBuilder_Append(sb,'}');

// The JWK format is automatically detected..
success := CkPublicKey_LoadFromString(pubKey,CkStringBuilder__getAsString(sb));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

// Get the JWK thumbprint (using SHA256)
Memo1.Lines.Add('JWK thumbprint: ' + CkPublicKey__getJwkThumbprint(pubKey,'SHA256'));

// Output:
// JWK thumbprint: NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs

// --------------------------------------------------------------
// Now let's do an EC public key:
CkStringBuilder_Clear(sb);
CkStringBuilder_Append(sb,'{ ');
CkStringBuilder_Append(sb,'  "kty": "EC",');
CkStringBuilder_Append(sb,'  "crv": "P-256",');
CkStringBuilder_Append(sb,'  "x": "tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA",');
CkStringBuilder_Append(sb,'  "y": "J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI"');
CkStringBuilder_Append(sb,'}');

success := CkPublicKey_LoadFromString(pubKey,CkStringBuilder__getAsString(sb));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

// Get the JWK thumbprint (using SHA256)
Memo1.Lines.Add('JWK thumbprint: ' + CkPublicKey__getJwkThumbprint(pubKey,'SHA256'));

// Output:
// JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4

CkPublicKey_Dispose(pubKey);
CkStringBuilder_Dispose(sb);

end;