Let's roll your dices on Algorand!
AlgoDices let players roll dices on-chain (both TestNet and MainNet), thanks the Randomness Beacon Application.
Starting from AVM 7, Algorand enables turstless randomness on chain,
thanks to the use of VRF:
with the vrf_verify
opcode an oracle Smart Contract can prove that a
pseudo-random value has been honestly computed off-chain through a VRF process
for a given blockchain round in the future.
AlgoDices makes use of the Randomness Beacon App deployed on TestNet and MainNet, which verifies, stores and provides the randomness to other applications for a given (future) round according to ARC-21.
NOTE: There is a non-negligible risk the MainNet Randomness Beacon miss certain round or becomes unavailable. In the latter case a new version of AlgoDices will be released.
AlgoDices ABI exposes two methods:
book_dices_roll
roll_dices
AlgoDices App requires players to opt-in.
Players can book dices rolls for future round, committing to future randomness:
{
"name": "book_dices_roll",
"args": [
{
"type": "uint64",
"name": "future_round",
"desc": "Future round booked for dices roll"
}
],
"returns": {
"type": "void"
},
"desc": "Book dices roll for a future round."
}
Althogh the more the round is distant in the future the better is for security,
AlgoDices App does not impose any minimum future_round
, leaving this check to
the client. An external App interacting with AlgoDices, for example, could
mandate future_round
to be greater than current round plus N
.
book_dices_roll
twice will overwrite the last booked round, even if
the previous booked randomness is unused.
Once the booked randomness is available, players can roll dices with "real"
number of faces (d2
, d4
, d6
, d8
, d10
, d12
, d20
, are common dices in
board games).
Players can roll multiple dices together (e.g. 2d6
, 1d8
and 1d20
),
up to 14.
future_round + 8
round to be sure that
their booked randomness is available in the Randomness Beacon App.
{
"name": "roll_dices",
"args": [
{
"type": "application",
"name": "randomness_beacon",
"desc": "Randomness Beacon App ID (TestNet: 110096026, MainNet: 947957720)"
},
{
"type": "uint8[]",
"name": "dices",
"desc": "Array of dices to roll (faces: 2, 4, 6, 8, 10, 12, 20)"
}
],
"returns": {
"type": "uint8[]",
"desc": "Dices roll result."
},
"desc": "Roll dices with a given number of faces. Fee: 3 * min_fee."
}
AlgoDice roll_dices
returns an array containing the dices results.
On-chain games can call AlgoDices imposing their own rules, for example:
a GameApp
calls roll_die
two times (on behalf of players Alice and Bob
participating in the game through proxy Contract Accounts controlled by
GameApp) as Inner Transactions executed in the same GameApp Call, requiring
dice = 6
. The highest result wins the match.
AlgoDices is also a trustless dices roller to play board games and
RPGs (like D&D) "over-the-phone": players can safely roll dices remotely,
with no mean of cheating. A Dungeon Master could ask the 🧝🏻♀️ Wizard Elf
to roll 8d6
to count 🔥 Fireball damages and be sure the result is correct!
You can easily roll dices with the Python 🎲 AlgoDices CLI.
Clone algo-dices
repo an open it:
$ git clone git@github.com:cusma/algo-dices.git
$ cd algo-dices
Install the virtual environment described in Pipfile
using pipenv
:
$ pipenv install
Lounch 🎲 AlgoDices CLI:
$ pipenv run python3 algodices.py
🎲 AlgoDices, let's roll verifiable random dices on Algornd!
Usage:
algodices.py optin [--test]
algodices.py book <future_rounds> [--test]
algodices.py roll <dice> ... [--test]
Commands:
optin Subscribe to AlgoDices.
book Book a die roll in future round.
roll Roll dices (e.g. 2d6, 1d8 and 1d20: roll 6 6 8 20).
Options:
-h, --help
-t, --test
-t
option to play on TestNet.
"word_1 ... word_25"
.
Example: roll 2d6, 1d8 and 1d20 on TestNet:
$ pipenv run python3 algodices.py roll 6 6 8 20 -t
--- 🎰 RESULTS 🎰
--- 🎲 d6: 1
--- 🎲 d6: 5
--- 🎲 d8: 1
--- 🎲 d20: 17
AlgoDices can be played also with DappFlow ABI Studio,
either on TestNet or MainNet, by logging with your wallet and importing
the AlgoDices contract.json
.
stateDiagram
[*] --> AlgoDices : create
AlgoDices --> AlgoDices_User : opt_in
AlgoDices_User --> Booked_Randomness : book_dices_roll
Booked_Randomness --> Booked_Randomness : book_dices_roll
state randomness <<choice>>
Booked_Randomness --> randomness : roll_dices(faces)
randomness --> Dices_Result : randomess_available
randomness --> Booked_Randomness : randomness_unavailable
Dices_Result --> AlgoDices_User
-
Multiple dices rolls on single round (e.g.[2d6, 1d8, 1d20]
); - Contract Account proxy for players;
- Switch to 512 bits math allowing more than 14 dices;
- Unlimited dices rolls (pay-per-roll).
Thanks to @ori-shem-tov, @fabrice102 for the Randomness Oracle Application and @barnjamin for the CoinFlipper example that inspired AlgoDices.
Another special thanks again to @fabrice102 for the precious and clever considerations on "safe" optimization of randomness source usage.