Pascal (Lazarus/Delphi)

Get Public Key from CSR

See more CSR Examples

Demonstrates how to get the public key from a CSR. 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.BinData,
  Chilkat.Asn,
  Chilkat.PublicKey,
  Chilkat.Xml,
  Chilkat.Pem;

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

procedure RunDemo;
var
  success: Boolean;
  pem: TPem;
  noPassword: string;
  strBase64: string;
  asn: TAsn;
  xml: TXml;
  strModulusHex: string;
  bd: TBinData;
  modulus64: string;
  xmlPubKey: TXml;
  pubkey: TPublicKey;
  preferPkcs1: Boolean;

begin
  success := False;

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

  pem := TPem.Create;

  //  No password is required.  Pass an empty password string..
  noPassword := '';
  success := pem.LoadPemFile('qa_data/csr/csr2.pem',noPassword);
  if (success <> True) then
    begin
      WriteLn(pem.LastErrorText);
      Exit;
    end;

  strBase64 := pem.GetEncodedItem('csr','','base64',0);

  asn := TAsn.Create;
  success := asn.LoadEncoded(strBase64,'base64');
  if (success <> True) then
    begin
      WriteLn(asn.LastErrorText);
      Exit;
    end;

  //  Convert the ASN.1 to XML.
  xml := TXml.Create;
  success := xml.LoadXml(asn.AsnToXml());
  WriteLn(xml.GetXml());
  WriteLn('----');

  strModulusHex := xml.GetChildContent('bits');
  WriteLn('strModulusHex = ' + strModulusHex);
  WriteLn('----');

  //  We need the modulus as base64.
  bd := TBinData.Create;
  bd.AppendEncoded(strModulusHex,'hex');
  modulus64 := bd.GetEncoded('base64');
  WriteLn('modulus64 = ' + modulus64);
  WriteLn('----');

  //  Build the XML for the public key.
  xmlPubKey := TXml.Create;
  xmlPubKey.Tag := 'RSAPublicKey';
  xmlPubKey.UpdateChildContent('Modulus',modulus64);
  //  The RSA exponent will always be decimal 65537 (base64 = AQAB)
  xmlPubKey.UpdateChildContent('Exponent','AQAB');

  WriteLn('RSA public key as XML:');
  WriteLn(xmlPubKey.GetXml());
  WriteLn('----');

  //  Load the XML into a Chilkat public key object.
  pubkey := TPublicKey.Create;
  success := pubkey.LoadFromString(xmlPubKey.GetXml());
  if (success <> True) then
    begin
      WriteLn(pubkey.LastErrorText);
      Exit;
    end;

  //  Show the public key as PEM.
  preferPkcs1 := True;
  WriteLn(pubkey.GetPem(preferPkcs1));


  pem.Free;
  asn.Free;
  xml.Free;
  bd.Free;
  xmlPubKey.Free;
  pubkey.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.