My first Iphone GPS app..developed under Windows and .NET

Function NCK (const aImei : string) : string;
var
aHash,S,  aKey : String;
Tmp : array [1..16] of integer;
i:integer;
 
begin
 
// Step 1 : The hash
// Calc MD5 hach for imei string (aImei)
// The result is a string of 32  hex digits aHash[1]....aHach[32];
 
 
aHash := Md5(aImei);
 
// Step 2 : Hash conversion.
// Convert The MD5 hash of imei to array of 16 integers (TMP)
// TMP[i] is the integer value corresponding to the concatenation
// of the two  hex digits aHash[i] and aHash[i+1]
 
 
for i:=1 to 16 do Tmp[i]:=StrToInt('$'+rightStr(leftstr(aHash,2*i),2));
 
// Step 3 : The code
// aKey[i] is the decimal digit obtained by the formula
// (((Tmp[i]+Tmp[i+8]) and $FF)*9) div $FF
 
aKey:='';
for i:=1 to 8 do aKey:=  aKey + IntToStr((((Tmp[i]+Tmp[i+8])and$FF)*9)div$FF);
 
// The result :)
while(length(akey)<8) do aKey:='0'+aKey; // format to 8 digits;
result:= aKey;
 
end;

function md5(const Input: String): String;
var
  hCryptProvider: HCRYPTPROV;
  hHash: HCRYPTHASH;
  bHash: array[0..$7f] of Byte;
  dwHashBytes: Cardinal;
  pbContent: PByte;
  i: Integer;
 
begin
  dwHashBytes := 16;
  pbContent := Pointer(PChar(Input));
 
  Result := '';
 
  if CryptAcquireContext(@hCryptProvider, nil, nil, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT or CRYPT_MACHINE_KEYSET) then
  begin
    if CryptCreateHash(hCryptProvider, CALG_MD5, 0, 0, @hHash) then
    begin
      if CryptHashData(hHash, pbContent, Length(Input) * sizeof(Char), 0) then
      begin
        if CryptGetHashParam(hHash, HP_HASHVAL, @bHash[0], @dwHashBytes, 0) then
        begin
          for i := 0 to dwHashBytes - 1 do
          begin
            Result := Result + Format('%.2x', [bHash[i]]);
          end;
        end;
      end;
      CryptDestroyHash(hHash);
    end;
 
    CryptReleaseContext(hCryptProvider, 0);
  end;
 
  Result := AnsiLowerCase(Result);
end;