uses XceedEncryptionLib_TLB 

var
  xSign : TXceedSigning; 
  xRSA : DXceedRSASigningMethod; 
  vaSource : OleVariant; 
  vaSignature : OleVariant; 
begin
  xSign := TXceedSigning.Create( self ); 
  xSign.License( 'your license key' );

  xRSA := CoXceedRSASigningMethod.Create();  

  try 
    { The following call to SetRandomKeyPair would, in the real world,  
      be replaced by the assignment of a Private Key to the PrivateKey property. } 

    vaSource := varEmpty; 
    xRSA.SetRandomKeyPair( 512, vaSource ); 
    xSign.SigningMethod := xRSA; 

    vaSource := 'This is the data to sign'; 

    xSign.Sign( vaSource, true ); 

    vaSignature := xRSA.Get_Signature;  

    { Do something with the Signature... }  

    ShowMessage( 'Signing successful!' );  

    if xSign.Verify(vaSource, True) then 
      ShowMessage( 'Data verified successfully' ) 
    else 
      // Should not happen 
      ShowMessage( 'Verification of signature failed' ); 
  except 
    on xErr : Exception do 
      ShowMessage( xErr.Message ); 
  end;  

  xSign.Free; 

end;