Provably fair gambling



A feature of crypto is not having to trust anyone, and therefore not being able to be cheated by anyone. So it is appropriate that crypto gambling operators are pioneering ways to provide trustless, provably fair gambling where they can’t cheat the players.

Provably fair gambling does not depend on cryptocurrency, it is just as easy for government currency operators to implement.


First, let’s define a couple of words in the limited sense in which they are used in this article.

Hashes: A long string of characters derived from other data. This is a mathematical problem that is extremely difficult to solve but when solved it gives the data its hashes. If a solution is presented it is easy to backwards test it to see if the solution is correct. So hashes are hard to solve but easy to verify a solution for.

Seeds: Extra data (a string of characters) applied to the hash which modifies what it hashes.

Provably fair casino games

Consider a card game that requires a random shuffle, such as blackjack. The idea is to stop the casino from deciding what the card will be, or knowing what the card will be before it is dealt. The online equivalent of cutting the deck, and no dealing from the bottom of the deck.

The provably fair way to do this is

Step 1: The site shuffles the deck as normal.

Step 2: The site provides you with a hash of the shuffle.

Step 3: You provide a random seed, manually or automatically generated, that the site cannot see or predict. This is done client side in your browser, not on the site’s server.

Step 4: Your seed changes the shuffle to something neither you nor the site can have known. This is the online equivalent of cutting the deck to the dealer shuffle.

Verification part 1: After the hand is dealt the initial deck is laid out and you can check that the deck started out as the hash the site provided indicated.

Verification part 2: The final deck is laid out so you can check that the initial deck was changed in accordance with the seed you provided.

If that all checks out then there was no funny business and you have just played a provably fair hand!

If you are a visual learner these concepts are displayed with pictures or a more detailed and technical explanation.

The same applies to games that require a random number such as roulette. This can all happen in the background without you realizing it, or you can use third-party online tools such as quickhash.

If you are cryptography and code literate you can check it for yourself by following these instructions. If that is not your idea of fun then you could rely on independent trustworthy experts that have done the verification for us. But then we are back to trusting someone which is what we are trying to avoid.

Provably fair gambling is brilliant to have to happen in the background but is too complicated to be useful for the masses, especially since you still have to trust the operator (such as allowing you to withdraw). But this is a new application of the technology so we can expect awareness to grow and usability in improving with time.

Provably fair sports betting

Fixed odds sportsbooks have always been provably fair in that they do not determine the result of the bet, or know it in advance. If they pay you the odds they said they would then they must be fair.

On the other hand, totalizers could be cheating their customers by not paying out the advertised % of the pool to the winners as only they know how much was bet and how much gets paid out.

Crypto solves this problem by allowing bets to happen on the blockchain, therefore, allowing anyone to check how much was in the pool and match that against how much was paid out.

Provably fair sites could still rip you off

A site with provably fair games could still take your funds or sell your IP address and login details to hackers; such incidents occur more often than rigged games. Value provably fair games but also follow these common sense tips to avoid crypto gambling scams.

I would rather bet with a known and trustworthy casino such as Cloudbet which does not yet provide provably fair games than an unknown and shady casino that does. Luckily we have, an all-around high-quality and trustworthy crypto casino where all the games are beautiful and provably fair. Read our review to learn more about Cloudbet.

Soon enough cryptography and multi-sig architecture will provide us with end-to-end trustless gambling services, oh and they will also have a 0% house edge. This is a great example of how crypto values are changing the online landscape and soon the world!

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