When a case site says its results are fair, it usually means one of two very different things. Provably fair vs RNG is the difference between a system you can check for yourself and a system that a third party checked for you. A provably fair pull can be recomputed on your own device from the seeds the site committed before you played. An RNG-certified draw was tested by an outside lab that issued a certificate you have to take on trust. Both aim at the same promise, that the result was not rigged, but they hand you very different amounts of proof.
Two ways a site can say the result is fair
Picture two shops that both promise a fair draw. The first shop seals its number in a tamper-proof envelope and hands you a stamp of it before you play, then opens the envelope afterward so you can check the stamp matches. You never had to trust the shopkeeper, because you did the checking. The second shop hires an independent inspector who visits, runs thousands of test draws on the machine, and posts a certificate on the wall saying the machine is sound. You still cannot open the machine, but a credible outsider vouched for it.
The first shop is provably fair. The second is RNG-certified. Provably fair moves the proof into your hands. RNG certification keeps the proof with an auditor and gives you their word for it. Neither is a scam by default, but they ask for different levels of faith, and that difference is the whole point of comparing them.
How provably fair works in a box pull
Provably fair is a commit-reveal scheme. Before your pull, the site generates a secret server seed and shows you only a hash of it, a one-way fingerprint that locks the value in without giving it away. You bring a client seed tied to your account, and a nonce, which is just a play count that ticks up with each open. When you open the box, the site combines those three inputs through HMAC, a keyed hash function, turns the resulting hex into a number, and maps that number to an item.
After you rotate your seeds, the site reveals the original server seed. Now you can do the whole calculation again yourself. You confirm the revealed seed matches the fingerprint you were shown up front, then recompute the outcome and check it lands on the same item. If both line up, the result was fixed before you played and was not changed afterward. This is why the model is called provably fair: the proof is a calculation anyone can run, not a promise. The what is provably fair guide walks through the full flow, and each ingredient has its own explainer, starting with the server seed.
How RNG certification works
RNG certification takes the opposite approach. RNG stands for random number generator, the piece of software that produces a site's outcomes. Instead of letting you verify each result, the operator hires an independent testing lab to examine the generator. The lab runs the RNG through very large batches of draws and applies statistical tests to confirm the outputs are evenly distributed, unpredictable, and free of patterns a player could exploit. If the software passes, the lab issues a certificate and often a seal the site can display.
The best known labs are iTechLabs, Gaming Laboratories International (GLI), and eCOGRA, all of which run independent testing and certification services for online gaming operators. Their certificate is a real trust signal, but notice what it is: a snapshot of the software taken at test time by a party you are trusting to be thorough and honest. You cannot rerun their tests, and you cannot tie the certificate to your specific pull. It vouches for the machine in general, not for the item you just got.
There is also a practical gap between the badge and the proof. A seal on a page is an image, and an image can be copied, kept up after a certificate lapses, or shown for a different product than the one you are opening. With a certification model you have no direct way to confirm the badge is current or that it even applies to the draw in front of you. You are trusting the site to display it honestly and the lab to have tested the right software. That is a reasonable trust to extend to a well known operator, but it is trust, not proof, and it is worth being clear-eyed about which one you are getting.
Provably fair vs RNG, side by side
The clearest way to see the split is to line the two models up on the questions that actually matter to a player.
| Question | Provably fair | RNG-certified |
|---|---|---|
| Who does the checking? | You, on your own device | An outside lab (iTechLabs, GLI, eCOGRA) |
| What does it prove? | This exact result came from the inputs committed before play, unaltered | The generator behaves randomly across large samples |
| Trust model | Verify it yourself, no faith required | Trust the auditor's certificate |
| Can you reproduce it yourself? | Yes, every completed pull | No, you rely on the lab's report |
| What it does NOT prove | The published item odds are accurate | The published item odds are accurate, or that your one pull was fair |
| Ties to your specific pull? | Yes, directly | No, it covers the software in general |
Read down the "who does the checking" and "can you reproduce it yourself" rows and the difference is stark. Provably fair is peer-level verification you control. RNG certification is top-down trust in an auditor. That is the honest heart of provably fair vs RNG, and no comparison table for a casino gets to skip it.
Your case site: provably fair, RNG-certified, or neither?
Most mystery-box and case-opening sites fall into one of three buckets, and it is worth knowing which one you are on before you decide how much to trust a pull.
- Provably fair. The site publishes its algorithm and lets you see your server seed hash, client seed, and nonce. You can recompute any completed pull. This is the strongest position for a player, because you never have to take the outcome on faith.
- RNG-certified only. The site shows a lab seal but gives you no seeds to check. You are trusting the certificate. That can be legitimate, but you personally cannot verify a single result.
- Neither. The site claims fairness with no published algorithm and no certificate. There is nothing here for you to check and nothing an outsider has vouched for. Treat a bare "provably fair" badge with no visible seeds as neither until you can actually run the check.
A site can technically do both, publishing a verifiable algorithm and holding a certificate, but in the box vertical the meaningful question is usually simpler: can you get to your seeds and recompute the pull, or not?
What neither model proves
Here is the limit both share, and it is the part most guides gloss over. A verification, whether it is your own recompute or a lab's certificate, confirms that outcomes are generated the way the site describes. It does not confirm that the odds behind those outcomes are the odds the site published. Provably fair proves the draw was committed and honestly derived from the seeds. It does not prove that the rare item really sits behind the ticket range the site claims, or that the probability table matches what is advertised. RNG certification proves the generator is random, not that the item weighting shown to you is the item weighting actually loaded.
In short, both models secure the mechanism, not the marketing around the odds. Keeping that straight is what separates a real understanding of fairness from a badge you glanced at. The dedicated what provably fair does not prove page covers this boundary in full.
How to check a provably fair pull yourself
If a site is genuinely provably fair, you do not have to trust this article either. Once your seeds have rotated and the server seed is revealed, you can recompute the pull:
- Before you play, copy the hashed server seed the site shows you. That is the fingerprint.
- Note your client seed and the nonce, or play count, for the pull you care about.
- After you rotate seeds, copy the revealed server seed.
- Paste all of it into the verifier below. It recomputes the outcome and confirms the revealed seed matches the fingerprint.
This is the one thing RNG certification cannot give you: a check you run yourself, on your own device, for your own pull. Everything you paste in stays in your browser and is sent nowhere.
Step 1Where did you play?
Using Ripster box / upgrade: HMAC-SHA256 over clientSeed:noncedetails
HMAC-SHA256 keyed with the server seed over clientSeed:nonce. The first 8 hex characters become a 32-bit integer, divided by 2^32 and multiplied by 100 for a roll in [0, 100). Items are sorted by item ID and selected by cumulative probability: the first item whose cumulative probability is at least the roll wins.
Where to find your numbers on Ripster.gg:
- Before rolling, copy the Server Seed Hash from the Provably Fair modal (also recorded per roll in Account History).
- After the roll, open the Provably Fair modal to copy the Server Seed, Client Seed and Nonce.
- Change your Client Seed anytime in Account Settings; doing so reveals the current Server Seed so all past rolls become verifiable.
Source: Ripster.gg's own fairness page
Step 2Paste your numbers
Runs entirely on your device via your browser's built-in cryptography. Don't take our word for it: open DevTools → Network, click the button, and watch: zero requests.
Runs entirely in your browser. Nothing you paste is sent anywhere.
The short version
Provably fair vs RNG comes down to who holds the proof. Provably fair puts a full recompute in your hands, so you can confirm any single pull came from committed seeds and was not altered. RNG certification puts the proof with an independent lab that tests the generator and issues a certificate you cannot reproduce. Provably fair is the stronger position for a player because it needs no faith, but even it stops at the mechanism: neither model promises the published odds are what the site actually loaded. Know which bucket your case site sits in, and when you can, run the check yourself.