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Hi guys, I know all provably fair casinos (for dice games anyway) create the roll result by combining their server seed + the client seed but how can you know if the seed generated by the casino server is truly fair? What if you were betting on rolls 10> but they altered their seed so it has a bigger chance of generating a <10 number? Thanks.

This link will probably clear all your doubts: https://dicesites.com/provably-fair They also have verifiers listed for a few famous dice sites. If you still wish to go above and beyond, you could message @NLNICO on bitcointalk. (he's the owner of the mentioned site)

Hi Joel thanks for participating, I’ve verified the roll and everything seems to match but question is, how do I know that the number generated by the server seed (the casino’s side) was indeed a random number from 1 to 100 and that they didn’t modify their algorithm so their server seed only generates number from 1 to 20 for example.

 If the game results were determined purely based upon a server seed, the server would be able to "try" a whole bunch, and find one it "likes" and use that.  That's why there's a client seed, which is controlled by the client.  It's important that the server picks the server-seed first, and it commits to it by giving you the "server seed hash". (should the server seed change, the server-seed hash would as well).

This proves the server seed is picked in advance of the client-seed, and not changing. If you make sure to pick your own client-seed, then there's no such thing as a "bad" or "good" server seed.

When user is able to put his own seed it actualy does not matter whether server seed is fair (pure random)
The important thing is the server seed must have been generated (and has not changed) before you provide your seed and make the roll.

So during verification process you need to check:
- Server seed used to generate roll result was given before the roll and has not changed: most probably you were provided with hash of the seed (usually its a daily seed which is published next day)
- Your seed was used to generate the roll output
- Any other input used to generate the roll output was not chosen (generated by) server. Usually it's nonce (which can be e.g. number how many roll you made that day etc.)

If you are worried then you should just use a random generator and just create a random client sees yourself instead of using the one provided to you.

The server and client seed are both used to calculate the rolls and also the nonce which is also the roll number.

Basically the casino already knows the roll results ahead of time, you do not since you don't have the unhashed seed however even if they know they will lose the next 100 rolls there is no way they can stop you from betting.

If they mandatory or randomly decided to reset everyone's seeds then I would get a little suspicious.

A site that has a lot of interest, then legal, like Bustadice, Fortunejack, SportsBet. It is a gambling site that is already trusted and is guaranteed to be unsafe.

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