/// <summary>
/// Encrypt a specific `Ballot` in the context of a specific `CiphertextElectionContext`
///
/// This method accepts a ballot representation that only includes `True` selections.
/// It will fill missing selections for a contest with `False` values, and generate `placeholder`
/// selections to represent the number of seats available for a given contest. By adding `placeholder`
/// votes
///
/// This method also allows for ballots to exclude passing contests for which the voter made no selections.
/// It will fill missing contests with `False` selections and generate `placeholder` selections that are marked `True`.
///
/// <param name="ballot">the selection in the valid input form</param>
/// <param name="internalManifest">the `InternalManifest` which defines this ballot's structure</param>
/// <param name="context">all the cryptographic context for the election</param>
/// <param name="ballotCodeSeed">Hash from previous ballot or hash from device</param>
/// <param name="nonce">an optional value used to seed the `Nonce` generated for this ballot
/// if this value is not provided, the secret generating mechanism of the OS provides its own</param>
/// <param name="shouldVerifyProofs">specify if the proofs should be verified prior to returning (default True)</param>
/// <returns>A `CiphertextBallot`</returns>
/// </summary>
public static unsafe CiphertextBallot Ballot(
PlaintextBallot ballot,
InternalManifest internalManifest,
CiphertextElectionContext context,
ElementModQ ballotCodeSeed,
ElementModQ nonce = null,
bool shouldVerifyProofs = true)
{
if (nonce == null)
{
var status = NativeInterface.Encrypt.Ballot(
ballot.Handle, internalManifest.Handle, context.Handle,
ballotCodeSeed.Handle, shouldVerifyProofs,
out NativeCiphertextBallot ciphertext);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"Encrypt Ballot Error Status: {status}");
}
return(new CiphertextBallot(ciphertext));
}
else
{
var status = NativeInterface.Encrypt.Ballot(
ballot.Handle, internalManifest.Handle, context.Handle,
ballotCodeSeed.Handle, nonce.Handle, shouldVerifyProofs,
out NativeCiphertextBallot ciphertext);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"EncryptWithNonce Ballot Error Status: {status}");
}
return(new CiphertextBallot(ciphertext));
}
}
/// <summary>
/// Given an encrypted BallotContest, validates the encryption state against
/// a specific encryption seed and public key
/// by verifying the accumulated sum of selections match the proof.
/// Calling this function expects that the object is in a well-formed encrypted state
/// with the `ballot_selections` populated with valid encrypted ballot selections,
/// the ElementModQ `description_hash`, the ElementModQ `crypto_hash`,
/// and the ConstantChaumPedersenProof all populated.
/// Specifically, the seed hash in this context is the hash of the ContestDescription,
/// or whatever `ElementModQ` was used to populate the `description_hash` field.
/// </summary>
public unsafe bool IsValidEncryption(
ElementModQ encryptionSeed,
ElementModP elGamalPublicKey,
ElementModQ cryptoExtendedBaseHash)
{
return(NativeInterface.CiphertextBallotContest.IsValidEncryption(
Handle, encryptionSeed.Handle, elGamalPublicKey.Handle,
cryptoExtendedBaseHash.Handle));
}
unsafe internal ElGamalKeyPair(ElementModQ secretKey)
{
var status = NativeInterface.ElGamalKeyPair.New(
secretKey.Handle, out Handle);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"ElGamalKeyPair Error Status: {status}");
}
}
/// <Summary>
/// Decrypt the ciphertext directly using the provided secret key.
///
/// This is a convenience accessor useful for some use cases.
/// This method should not be used by consumers operating in live secret ballot elections.
/// </Summary>
unsafe public ulong?Decrypt(ElementModQ secretKey)
{
ulong plaintext = 0;
var status = NativeInterface.ElGamalCiphertext.DecryptWithSecret(
Handle, secretKey.Handle, ref plaintext);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"Decrypt Error Status: {status}");
return(null);
}
return(plaintext);
}
public unsafe CiphertextElectionContext(ulong numberOfGuardians,
ulong quorum,
ElementModP publicKey,
ElementModQ commitmentHash,
ElementModQ manifestHash)
{
var status = NativeInterface.CiphertextElectionContext.Make(
numberOfGuardians, quorum, publicKey.Handle, commitmentHash.Handle, manifestHash.Handle, out Handle);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"CiphertextElectionContext Error Status: {status}");
}
}
/// <summary>
/// Encrypts a message with a given random nonce and an ElGamal public key.
///
/// <param name="plaintext"> Message to elgamal_encrypt; must be an integer in [0,Q). </param>
/// <param name="nonce"> Randomly chosen nonce in [1,Q). </param>
/// <param name="publicKey"> ElGamal public key. </param>
/// <returns>A ciphertext tuple.</returns>
/// </summary>
unsafe public static ElGamalCiphertext Encrypt(
ulong plaintext, ElementModQ nonce, ElementModP publicKey)
{
var status = NativeInterface.ElGamal.Encrypt(
plaintext, nonce.Handle, publicKey.Handle,
out NativeElGamalCiphertext ciphertext);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"Encrypt Error Status: {status}");
return(null);
}
return(new ElGamalCiphertext(ciphertext));
}
protected override bool Free()
{
if (IsClosed)
{
return(true);
}
var status = ElementModQ.Free(this);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"ElementModQ Error Free: {status}");
return(false);
}
return(true);
}
/// <summary>
/// Encrypt a specific `Ballot` in the context of a specific `CiphertextElectionContext`
///
/// This method accepts a ballot representation that only includes `True` selections.
/// It will fill missing selections for a contest with `False` values, and generate `placeholder`
/// selections to represent the number of seats available for a given contest. By adding `placeholder`
/// votes
///
/// This method also allows for ballots to exclude passing contests for which the voter made no selections.
/// It will fill missing contests with `False` selections and generate `placeholder` selections that are marked `True`.
///
/// This version of the encrypt method returns a `compact` version of the ballot that includes a minimal representation
/// of the plaintext ballot along with the crypto parameters that are required to expand the ballot
///
/// <param name="ballot">the selection in the valid input form</param>
/// <param name="internalManifest">the `InternalManifest` which defines this ballot's structure</param>
/// <param name="context">all the cryptographic context for the election</param>
/// <param name="ballotCodeSeed">Hash from previous ballot or hash from device</param>
/// <param name="nonceSeed">an optional value used to seed the `Nonce` generated for this ballot
/// if this value is not provided, the secret generating mechanism of the OS provides its own</param>
/// <param name="shouldVerifyProofs">specify if the proofs should be verified prior to returning (default True)</param>
/// <returns>A `CiphertextBallot`</returns>
/// </summary>
public static unsafe CompactCiphertextBallot CompactBallot(
PlaintextBallot ballot,
InternalManifest internalManifest,
CiphertextElectionContext context,
ElementModQ ballotCodeSeed,
bool verifyProofs = true)
{
var status = NativeInterface.Encrypt.CompactBallot(
ballot.Handle, internalManifest.Handle, context.Handle,
ballotCodeSeed.Handle, verifyProofs,
out NativeCompactCiphertextBallot ciphertext);
if (status != Status.ELECTIONGUARD_STATUS_SUCCESS)
{
Console.WriteLine($"Encrypt CompactBallot Error Status: {status}");
}
return(new CompactCiphertextBallot(ciphertext));
}
/// <Summary>
/// Make an elgamal keypair from a secret.
/// </Summary>
unsafe static public ElGamalKeyPair FromSecret(ElementModQ secretKey)
{
return(new ElGamalKeyPair(secretKey));
}
