Private Voting using SEAL

dotnet/examples/PVT_voting.cs

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+using System;
+using Microsoft.Research.SEAL;
+
+namespace SEALNetExamples
+{
+    partial class Examples
+    {
+        private static void ExamplePrivateVoting()
+        {
+            Utilities.PrintExampleBanner("Private Voting System ARKVIEN");
+
+            // Set up encryption parameters
+            using EncryptionParameters parms = new EncryptionParameters(SchemeType.BFV);
+            ulong polyModulusDegree = 4096;
+            parms.PolyModulusDegree = polyModulusDegree;
+            parms.CoeffModulus = CoeffModulus.BFVDefault(polyModulusDegree);
+            parms.PlainModulus = new Modulus(1024);
+
+            // Create a SEALContext object
+            using SEALContext context = new SEALContext(parms);
+
+            // Print the parameters
+            Utilities.PrintLine();
+            Console.WriteLine("Set encryption parameters and print");
+            Utilities.PrintParameters(context);
+
+            // Generate keys
+            using KeyGenerator keygen = new KeyGenerator(context);
+            using SecretKey secretKey = keygen.SecretKey;
+            keygen.CreatePublicKey(out PublicKey publicKey);
+
+            // Create encryptor, evaluator, and decryptor
+            using Encryptor encryptor = new Encryptor(context, publicKey);
+            using Evaluator evaluator = new Evaluator(context);
+            using Decryptor decryptor = new Decryptor(context, secretKey);
+
+            // Generate relinearization keys
+            keygen.CreateRelinKeys(out RelinKeys relinKeys);
+
+            // Simulate a private voting system with 3 voters
+            int[] votes = { 1, 0, 1 }; // 1 = Yes, 0 = No
+            using Ciphertext encryptedTally = new Ciphertext();
+
+            // Encrypt each vote and homomorphically add them to the tally
+            for (int i = 0; i < votes.Length; i++)
+            {
+                using Plaintext votePlain = new Plaintext(votes[i].ToString());
+                using Ciphertext encryptedVote = new Ciphertext();
+                encryptor.Encrypt(votePlain, encryptedVote);
+
+                if (i == 0)
+                {
+                    encryptedTally.Set(encryptedVote);
+                }
+                else
+                {
+                    evaluator.AddInplace(encryptedTally, encryptedVote);
+                }
+            }
+
+            // Decrypt the final tally
+            using Plaintext decryptedTally = new Plaintext();
+            decryptor.Decrypt(encryptedTally, decryptedTally);
+
+            // Print the result
+            Utilities.PrintLine();
+            Console.WriteLine("Private Voting System Results:");
+            Console.WriteLine($"Total 'Yes' votes: {decryptedTally}");
+
+            /*
+            Explanation:
+            - Each voter's vote is encrypted using the public key.
+            - The votes are homomorphically added together without decrypting them.
+            - The final tally is decrypted to reveal the total number of 'Yes' votes.
+            - This ensures that individual votes remain private while still allowing the computation of the final result.
+            */
+        }
+    }
+}