back to article Kiwi hackers crack crap algo, showcase 40c-a-litre DIY fuel discounts

New Zealanders could print their own non-expiring 40c fuel discount vouchers thanks to a shoddy algorithm that a hacking duo has broken. The algorithm developed by Countdown affects petrol stations operated by national energy provider Z and is designed as an incentive for consumers who shop at various supermarkets. Countdown …

  1. Anonymous Coward
    Anonymous Coward

    Tesco?

    I wonder...

    1. This post has been deleted by its author

  2. Anonymous Coward
    Anonymous Coward

    ...Value Algorithm.

  3. Anonymous Coward
    Anonymous Coward

    Not news

    Anon for this post as I know the background on this this system and have a fair idea who came up with it. People in the industry have known this for a while.

    Developer I spoke with knew it was weak, even at the time, but was seen as quick n dirty hack years ago, that could work offline and be very simple. But not even a simple hash to make it harder to generate valid codes... silly.

    System will be replaced in the near future. Supermarket chain will move to onetime codes, the apps running on terminals will get updates and check DFD online, but all takes time with a bunch of companies needing to sync systems.

    Until then, you have to present the DFD in person which means you would have to print a relatively realistic docket and operators would suspect if you did 40c off dockets when they weren't on offer at the local supermarket at the time. Probably not a huge loss to the oil companies anyway; they give the discount to get you in the service station and maybe buy coffee and pies, so even if you have a homemade DFD, still works.

    And this is NZ, so probably not going to be widely exploited.

  4. Anonymous Coward
    Anonymous Coward

    Get 40c off fuel

    Pay 5 x more than you should for that 'discount chocolate bar' promo touted by the cashier.

  5. Anonymous Coward
    Anonymous Coward

    Surely this isn't news?

    Normal coupon barcodes have been broken for many years now - hence why some of the newer coupons are now 2D barcodes with a unique ID.

    Most of the stores still accept 1D barcodes for coupons though so you could, in theory, knock up a coupon to give you large discounts on just about any item you wanted.

    The stores likely have some kind of algorithm to detect discounts that are far too high but that probably just involves a human checking the coupon looks legit.

    This is, of course, fraud and counterfeiting which if you're going down that route then you may as well just print tenners but technically it's possible...

  6. Stuart Elliott

    Refreshing Change

    Well, it makes a change the petrol company being shafted by the consumer.

    Oil at 2004 price/barrel - is petrol at the pump anything close to the same parity?

    1. Anonymous Coward
      Anonymous Coward

      Re: Refreshing Change

      Don't forget the governments take that is put on top of what the petrol company charges and then there are green taxes on top of that.

      Start by removing the green tax and you already have your discount. Cut the government tax and petrol becomes a reasonable priced commodity.

      1. Deltics

        Re: Refreshing Change

        I think you're missing the point.... In the UK (and elsewhere) pump prices have fallen back at more or less the same rate as the oil price. In NZ the prices at the pump are still at 2009/2010 prices whilst oil has fallen back to 2004/5 levels.

        Taxes have nothing whatsoever to do with the failure of pump prices to track oil prices in a reasonable and relative fashion.

        When the oil price goes up, pump prices go up almost instantly. When the oil price goes down, all sorts of reasons and excuses are trotted out to explain why the pump price does not follow suit. Reasons and excuses that for some reason never seem to apply when prices are going the other way.

        Exchange rates are also a factor since oil is traded in US$ but even with this taken into account there are massive discrepancies in the pump prices in NZ that cannot be accounted for by US:NZ forex or taxation.

        For example, you will (not sometimes, always) drive past 2 or 3 stations all at $179.9 (not even a few cents either way - all EXACTLY the same price) within spitting distance of each other, then 2-3 km further up the road another station, even often of the same brand, will be $168.9 or even cheaper and if there are 2 or 3 stations there, then these too will form a nice little "cluster" at that lower price.

        Did someone say "price fixing" ?

    2. daemonoid

      Re: Refreshing Change

      Yes, yes it is! I was in the UK and paid less than a pound a litre for diesel the other day. Not done that since about 10 years ago!

      The fuel duty has risen in the time since 2004, as have the taxes on the oil companies (by up to 32%) - that's a particularly sneaky one as the gov gets to rake in the revenue and blame the price increases on the oil companies. The gov takes almost two thirds of the cost of fuel at the pump through duty & VAT, then takes a cut of the profit of the oil companies.

      To paraphrase Clarkson... It's amazing that anyone can go out, find oil, get it out of the ground, ship it part way round the world, refine it and then deliver it to a forecourt for about 50p a litre... It's cheaper than a bottle of mineral water from Scotland.

      1. TeeCee Gold badge
        Unhappy

        Re: Refreshing Change

        Yes, it is something of a novelty to see the litres clicking up faster than the pounds, isn't it?

        Then again, some of us remember when the gallons clicked up faster than the pounds.....

  7. JeffyPoooh
    Pint

    Flaw in their evil scheme...

    They still need to pay for the residual price.

    Pay at pump usually involves a traceable Credit or Debit Card.

    Pay with cash involves standing in front of three or four CCTV cameras at the cash register.

    Unless they know a fuel pump that accepts Bitcoin, they'll inevitably be caught.

    1. Robert Helpmann??
      Childcatcher

      Re: Flaw in their evil scheme...

      Pay at pump usually involves a traceable Credit or Debit Card.

      What? You don't have pre-paid cards? Or cameras outside that might catch the vehicle's tag? You are probably right that using this cheat will get you caught, but for the wrong reasons. It should be noted that fraud of this sort is especially difficult to detect as it does not involve avoiding payment completely, which is what most companies are on the lookout for.

  8. Crisp

    "[The] fault lies with the design of the algorithm and not with Z"

    Was this algorithm forced on Z? Were they made to implement it without checking it first?

  9. TeeCee Gold badge
    Thumb Down

    Pictures.

    Surely in this context, blanking out the faces with the laughing man image would be more appropriate?

  10. Androgynous Cupboard Silver badge

    Shurely calling x-50 an algorithm is stretching it a bit?

  11. David Roberts

    Just back from NZ

    As far as I could tell it was cheaper to buy fuel from BP without a discount than from Z with the discount.

    Still more expensive in the UK. £1 per litre is about $2.20 per litre.

    1. Pomgolian
      Pint

      Re: Just back from NZ

      >Still more expensive in the UK. £1 per litre is about $2.20 per litre.

      You should have stayed - it's typically around $1.70 right now, which works out at 77pence.

    2. GrumpyKiwi

      Re: Just back from NZ

      It depends upon where you were buying from geographically more than which company. If you were buying up north (around Whangarei where the refinery is) then you could easily pay $0.20 - 0.30 per litre less than if you were buying somewhere down south. It could cost even more if you buy from one of the small country service stations.

      1. Deltics

        Re: Just back from NZ

        Nope, this effect too is inconsistent.

        There is a BP station in Hamilton which I use often whilst down there in business. Last year when BP stations in Auckland were up in the high $1.90's or even $2, that BP station in the 'Tron was in the low $1.80's.

        Hamilton is about 130 km south of Auckland so the "transport cost" explanation for higher fuel prices doesn't wash any more than the "taxes" or "exchange rates" excuses.

        Similarly, when on a weekend break in Taupo, we were shocked to find fuel 10 - 15c higher than the highest price in Auckland, yet on the road to Rotorua, in a rural "backwater" we came across a station 5c cheaper than even the CHEAPEST in AKL.

        The one thing that is utterly consistent is the fact that stations within close proximity of each other (within 1km and most especially when visible from one and each other) are ALWAYS, but ALWAYS at the same price despite the HUGE variation that otherwise exists around the country or even within the same town or city.

        Curious that, eh ?

    3. Deltics

      Re: Just back from NZ

      Not sure where in NZ you were, but in Auckland BP are routinely more expensive than all other brands, but where-ever a BP station sits, mysteriously ALL the stations within spitting distance of that station are typically at the same price.

      Travel outside the sphere of influence of that BP station and Mobil are among the cheapest with Gull being cheaper still. Z usually fall between Mobil and BP with Caltex being closer to Mobil and Gull. But again, whatever the most expensive station is sets the price within approx. 1km of that station.

      Yet outside of that effect, variation between stations can be HUGE (usually 10 or even as much as 20 c/L) .

      1. GrumpyKiwi

        Re: Just back from NZ

        BP certainly can take the p*** all right. The station by the Waterview off-ramp is consistently $0.10 per litre more expensive than any other station I regularly pass - including other BP stations. The BP I used to use in New Lynn (yes I'm a Westie) was consistently the cheapest in the area on the other hand.

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like