(Delphi) URL Signing for Google Maps API

Demonstrates how to sign a URL for the Google Maps API.

Download Chilkat Crypt ActiveX

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    CHILKATCRYPT2Lib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: TChilkatCrypt2;
success: Integer;
sig: String;

begin
crypt := TChilkatCrypt2.Create(Self);

//  Any string argument automatically begins the 30-day trial.
success := crypt.UnlockComponent('Anything for 30-day trial.');
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

//  The output will be modified Base64.
//  Modified Base64 for URLs replaces the '+' and '/' characters
//  of standard Base64 with '-' and '_' respectively, so that these
//  Base64 signatures no longer need to be URL-encoded.
crypt.EncodingMode := 'modBase64';

//  NOTE: At the time of this writing, the "modBase64" encoding mode is
//  available in the pre-release build only.  Send email to
//  support@chilkatsoft.com if you need a pre-release.  This feature will be
//  included in the next official release.

//  Set the hash algorithm to sha-1
crypt.HashAlgorithm := 'sha-1';

//  Set the HMAC key (this is the private key provided by Google)
crypt.SetHmacKeyEncoded('vNIXE0xscrmjlyV-12Nj_BvUPaw=','modBase64');

//  Compute the URL signature
sig := crypt.HmacStringENC('/maps/api/geocode/json?address=New+York&sensor=false&client=clientID');

//  The result should be KrU1TzVQM7Ur0i8i7K3huiw3MsA=
Memo1.Lines.Add(sig);
end;