138 lines
4.0 KiB
Rust
138 lines
4.0 KiB
Rust
use {
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crate::zk_token_elgamal::pod,
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bytemuck::{Pod, Zeroable},
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};
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#[cfg(not(target_os = "solana"))]
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use {
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crate::{
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encryption::elgamal::{ElGamalCiphertext, ElGamalKeypair, ElGamalPubkey},
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errors::ProofError,
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instruction::Verifiable,
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sigma_proofs::zero_balance_proof::ZeroBalanceProof,
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transcript::TranscriptProtocol,
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},
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merlin::Transcript,
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std::convert::TryInto,
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};
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/// This struct includes the cryptographic proof *and* the account data information needed to verify
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/// the proof
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///
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/// - The pre-instruction should call CloseAccountData::verify_proof(&self)
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/// - The actual program should check that `balance` is consistent with what is
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/// currently stored in the confidential token account
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///
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#[derive(Clone, Copy, Pod, Zeroable)]
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#[repr(C)]
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pub struct CloseAccountData {
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/// The source account ElGamal pubkey
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pub pubkey: pod::ElGamalPubkey, // 32 bytes
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/// The source account available balance in encrypted form
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pub ciphertext: pod::ElGamalCiphertext, // 64 bytes
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/// Proof that the source account available balance is zero
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pub proof: CloseAccountProof, // 64 bytes
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}
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#[cfg(not(target_os = "solana"))]
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impl CloseAccountData {
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pub fn new(
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keypair: &ElGamalKeypair,
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ciphertext: &ElGamalCiphertext,
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) -> Result<Self, ProofError> {
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let pod_pubkey = pod::ElGamalPubkey(keypair.public.to_bytes());
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let pod_ciphertext = pod::ElGamalCiphertext(ciphertext.to_bytes());
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let mut transcript = CloseAccountProof::transcript_new(&pod_pubkey, &pod_ciphertext);
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let proof = CloseAccountProof::new(keypair, ciphertext, &mut transcript);
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Ok(CloseAccountData {
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pubkey: pod_pubkey,
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ciphertext: pod_ciphertext,
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proof,
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})
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}
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}
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#[cfg(not(target_os = "solana"))]
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impl Verifiable for CloseAccountData {
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fn verify(&self) -> Result<(), ProofError> {
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let mut transcript = CloseAccountProof::transcript_new(&self.pubkey, &self.ciphertext);
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let pubkey = self.pubkey.try_into()?;
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let ciphertext = self.ciphertext.try_into()?;
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self.proof.verify(&pubkey, &ciphertext, &mut transcript)
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}
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}
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/// This struct represents the cryptographic proof component that certifies that the encrypted
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/// balance is zero
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#[derive(Clone, Copy, Pod, Zeroable)]
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#[repr(C)]
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#[allow(non_snake_case)]
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pub struct CloseAccountProof {
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pub proof: pod::ZeroBalanceProof,
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}
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#[allow(non_snake_case)]
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#[cfg(not(target_os = "solana"))]
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impl CloseAccountProof {
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fn transcript_new(
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pubkey: &pod::ElGamalPubkey,
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ciphertext: &pod::ElGamalCiphertext,
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) -> Transcript {
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let mut transcript = Transcript::new(b"CloseAccountProof");
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transcript.append_pubkey(b"pubkey", pubkey);
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transcript.append_ciphertext(b"ciphertext", ciphertext);
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transcript
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}
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pub fn new(
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keypair: &ElGamalKeypair,
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ciphertext: &ElGamalCiphertext,
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transcript: &mut Transcript,
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) -> Self {
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let proof = ZeroBalanceProof::new(keypair, ciphertext, transcript);
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Self {
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proof: proof.into(),
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}
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}
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pub fn verify(
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&self,
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pubkey: &ElGamalPubkey,
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ciphertext: &ElGamalCiphertext,
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transcript: &mut Transcript,
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) -> Result<(), ProofError> {
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let proof: ZeroBalanceProof = self.proof.try_into()?;
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proof.verify(pubkey, ciphertext, transcript)?;
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Ok(())
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_close_account_correctness() {
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let keypair = ElGamalKeypair::new_rand();
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// general case: encryption of 0
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let ciphertext = keypair.public.encrypt(0_u64);
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let close_account_data = CloseAccountData::new(&keypair, &ciphertext).unwrap();
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assert!(close_account_data.verify().is_ok());
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// general case: encryption of > 0
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let ciphertext = keypair.public.encrypt(1_u64);
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let close_account_data = CloseAccountData::new(&keypair, &ciphertext).unwrap();
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assert!(close_account_data.verify().is_err());
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}
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}
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