static void Main(string[] args)
{
//HomoExample();
/*
* Create a list of shareholders.
* We need to set the number of shares so that if enough shareholders want to decrypt the secret they can.
* But if the treshold is not met, they should not be able to decrypt the information
*/
List <PasswordProtectedShareHolder> shareHolders = new List <PasswordProtectedShareHolder>
{
CreateShareholder("xxx", id: 1, numberOfShares: 2),
CreateShareholder("yyy", 2, numberOfShares: 2),
CreateShareholder("zzz", 3, numberOfShares: 4)
};
/*
* HSM: Hardware security module - A machine that should zeroize (delete all keys/data) in case of phisical temper.
* HSM never exposes the keys that it stores. The user of the HSM can do cryptographic operations with the keys, and create new keys.
*/
FakeHsmFactory fakeHsmFactory = new FakeHsmFactory(Path.GetTempFileName());
/*
* Creates the homomorphic encryption context (encryption details), and helper methods for homomorphic cryptography operations.
*/
HomomorphicKeyManager keyManager = new HomomorphicKeyManager();
/*
* A fake implementation of a database repository
*/
FakeCentralDbRepository fakeCentralDbRepository = new FakeCentralDbRepository(numberOfCandidates: 3);
/*
* Treshold, is the minimum number of shares needed to decrypt the splited secret.
* ShareManager not tied to homomorphic encryption, it can be used with any type of encryption.
*/
ShareManager sm = new ShareManager(treshold: 4, hsmFactory: fakeHsmFactory, keyManager: keyManager,
centralDbRepository: fakeCentralDbRepository, publicShareHolders: shareHolders.Select(sh => (IPublicShareHolder)sh).ToList());
/*
* This will save the splited secret using the shareholder method to save the secret
* Also this will store in the database the public key that will be used to encrypt the votes.
* Along with the public key, the master key handle from the HSM will be saved as well in the database.
*/
sm.GenerateSplitedSecret(hsmSecret: null, electionId: 1).Wait();
/*
* A key chain needs to be created so that every voting booth has a certificate signed by a certificate authority(Voting place-2019)
* Voting place CA would be signed by a voting city CA, and up to voting country+electionID.
* It is important for the vooting booth to sign all the votes that it prints so that the voter can later verify that he's vote has been taken into consideration.
* If the voter wouldn't see his vote in the public database, he could proove to the authorities that his vote was registered by a booth.
* Online he could see the hour of the vote, the vote hash, vote encrypted data, voting booth public certificate that can be used to validate the vote.
*/
var booth = new VotingBooth(new SignCertificate(StoreName.My, StoreLocation.CurrentUser, "ceapa"), keyManager);
List <VotingBooth> votingBooths = new List <VotingBooth>
{
booth
};
/*
* A voting place is a room with voting booth's. It has the responsibility of periodically geting the data from the booth and to publish it on the public database.
* The voters are saved in a separate database unlinked from the actual votes. You want them unlinked so that in future if the cipher is cracked,
* no one will know what was my vote unless I showed it to somebody else.
* FakeLocalBoothFinder is just gives for now instances of the voting booths.
* But in a real scenario, this would just be a wrapper over the booth that would invoke the Voting Booth Server.
* Only VotingPlace can access the Voting Booth Server (Using certificate authentication maybe) *
*/
VotingPlace votingPlace = new VotingPlace(fakeCentralDbRepository, new FakeLocalBoothFinder(votingBooths), 1, 1);
booth.AddVote(new List <uint> {
0, 1, 0
}, new Voter {
ID = "x", DisplayName = "X-ulescu"
});
booth.AddVote(new List <uint> {
0, 1, 0
}, new Voter {
ID = "y", DisplayName = "Y-ulescu"
});
/*
* Save the votes in the public database.
* Save the voters in the public database(it may be that this is private, only to have a hash of the person?)
*/
votingPlace.SaveVotesPublicly().Wait();
/*
* Vote aggregator. Code that adds the votes together.
* Note that the aggregator only takes the context as the parameter (Not even the public key)
* So anyone can actually do math operations on homomorphic encryption if they know the parameters.
*/
VoteAggregator aggregator = new VoteAggregator(keyManager);
var aggregatedResult = aggregator.AddVotes(fakeCentralDbRepository.GetPublicVotesAsync().Result);
/*
* Combine the secret together again using the shareholder with ID 3(he has 4 shares, and that is the treshold for decryption)
*/
byte[] res = sm.GetCombinedSecret(shareHolders.Where(s => s.ID == 3).Select(s => (IAuthenticatedShareHolder)s).ToList(), null, 1).Result;
/*
* You can only read the votes using the combined secret and the context.
* The VoteReader should only decrypt aggregates. They should agree only on a few decryptions.
* Maybe a few tests on smaller aggregates, assuming that they already knwo the actual answer for those small agregates.
*/
VoteReader voteReader = new VoteReader(homomorphicKeyManager: keyManager, secretKeyData: res);
var decryptedVotes = voteReader.DecryptVotes(aggregatedResult);
}