1 unstable release
0.1.0 | Jul 8, 2021 |
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#3 in #lottery
10KB
188 lines
verilot
verilot (verifiable lottery) is a command line tool for running and verifying one-time lotteries.
Install
Install Rust and Cargo with Rustup.
Install verilot with cargo install verilot
.
Usage
The verifiable lottery process has a few overall steps.
- Generate secret random data and publish commitment.
- Gather entrants.
- Run lottery.
- Publish results (including secret random data).
- Users verify results.
Generating Secret
verilot generate /path/to/secret.txt > /path/to/commitment.txt
generate
will write the secret bytes (hex-encoded) to the path given in the argument.
It will output the commitment to stdout.
We recommend publishing the commitment for the participants in your lottery to verify with.
If you publish the secret, users can use compute power to increase their chances of winning the lottery.
Running Lottery
printf "foo\nbar\nbaz" | verilot lottery --secret /path/to/secret.txt > /path/to/results.json
lottery
takes the list of entrants as newline-separated arbitrary strings as input on stdin.
It outputs a json structure with the outcome to stdout.
The whole json file should be published for entrants to verify fairness.
The output contains a field of the entrants in order of hash value. Winners are the entrants with the lowest hash value.
Hashing Input
Since it's common to not want to publish the raw entrant input strings (which is required for verifying fairness), we provide a subcommand to hash raw input strings.
printf "foo\nbar\nbaz" | verilot digest
# Output:
# abcdef... "foo"
# abcdef... "bar"
# abcdef... "baz"
You can then easily split out the hash with cut -f1 -d' '
.
You'll need to manually pair the hashes in the results with the output of digest
to get the appropriate winners.
Verifying
cat /path/to/results.json | verilot verify --commitment "abcdef"
verify
takes the json results of the lottery as input on stdin.
It optionally takes the commitment as hex string.
Verify will exit with a non-zero code if the verification fails.
Algorithm
Each entrant gets a "ticket" calculated as Hash(entrant_data | secret)
.
Winners are the entrants with the lowest tickets.
Dependencies
~2.5–3.5MB
~62K SLoC