create an ElGamal registry program

Author: samkim-crypto

Cargo.toml

@@ -75,6 +75,7 @@ members = [
   "token/confidential-transfer/proof-extraction",
   "token/confidential-transfer/proof-generation",
   "token/confidential-transfer/proof-tests",
+  "token/confidential-transfer/elgamal-registry",
   "token/client",
   "utils/cgen",
   "utils/test-client",

token/confidential-transfer/elgamal-registry/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "spl-elgamal-registry"
+version = "0.1.0"
+description = "Solana ElGamal Registry"
+authors = ["Solana Labs Maintainers <[email protected]>"]
+repository = "https://github.com/solana-labs/solana-program-library"
+license = "Apache-2.0"
+edition = "2021"
+
+[features]
+no-entrypoint = []
+test-sbf = []
+
+[dependencies]
+bytemuck = { version = "1.18.0", features = ["derive"] }
+solana-program = "2.0.3"
+solana-zk-sdk = "2.0.3"
+spl-pod = { version = "0.4.0", path = "../../../libraries/pod" }
+spl-token-confidential-transfer-proof-extraction = { version = "0.1.0", path = "../proof-extraction" }
+
+[lib]
+crate-type = ["cdylib", "lib"]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

token/confidential-transfer/elgamal-registry/src/entrypoint.rs

@@ -0,0 +1,14 @@
+//! Program entrypoint
+
+#![cfg(all(target_os = "solana", not(feature = "no-entrypoint")))]
+
+use solana_program::{account_info::AccountInfo, entrypoint::ProgramResult, pubkey::Pubkey};
+
+solana_program::entrypoint!(process_instruction);
+fn process_instruction(
+    program_id: &Pubkey,
+    accounts: &[AccountInfo],
+    instruction_data: &[u8],
+) -> ProgramResult {
+    crate::processor::process_instruction(program_id, accounts, instruction_data)
+}

token/confidential-transfer/elgamal-registry/src/instruction.rs

@@ -0,0 +1,96 @@
+use solana_program::{
+    program_error::ProgramError,
+    pubkey::{Pubkey, PUBKEY_BYTES},
+};
+
+#[derive(Clone, Debug, PartialEq)]
+#[repr(u8)]
+pub enum RegistryInstruction {
+    /// Initialize an ElGamal public key registry for an account.
+    ///
+    /// 0. `[writable]` The account to initialize
+    /// 1. `[]` Instructions sysvar if `VerifyPubkeyValidity` is included in the
+    ///    same transaction or context state account if `VerifyPubkeyValidity`
+    ///    is pre-verified into a context state account.
+    /// 2. `[]` (Optional) Record account if the accompanying proof is to be
+    ///    read from a record account.
+    CreateRegistry {
+        /// The owner of the ElGamal registry account
+        owner: Pubkey,
+        /// Relative location of the `ProofInstruction::PubkeyValidityProof`
+        /// instruction to the `CreateElGamalRegistry` instruction in the
+        /// transaction. If the offset is `0`, then use a context state account
+        /// for the proof.
+        proof_instruction_offset: i8,
+    },
+    /// Update an ElGamal public key registry with a new ElGamal public key.
+    ///
+    /// 0. `[writable]` The account to initialize
+    /// 1. `[signer]` The owner of the ElGamal public key registry
+    /// 2. `[]` Instructions sysvar if `VerifyPubkeyValidity` is included in the
+    ///    same transaction or context state account if `VerifyPubkeyValidity`
+    ///    is pre-verified into a context state account.
+    /// 3. `[]` (Optional) Record account if the accompanying proof is to be
+    ///    read from a record account.
+    UpdateRegistry {
+        /// Relative location of the `ProofInstruction::PubkeyValidityProof`
+        /// instruction to the `UpdateElGamalRegistry` instruction in the
+        /// transaction. If the offset is `0`, then use a context state account
+        /// for the proof.
+        proof_instruction_offset: i8,
+    },
+}
+
+impl RegistryInstruction {
+    /// Unpacks a byte buffer into a `RegistryInstruction`
+    pub fn unpack(input: &[u8]) -> Result<Self, ProgramError> {
+        let (&tag, rest) = input
+            .split_first()
+            .ok_or(ProgramError::InvalidInstructionData)?;
+
+        Ok(match tag {
+            0 => {
+                let owner = rest
+                    .get(..PUBKEY_BYTES)
+                    .and_then(|x| Pubkey::try_from(x).ok())
+                    .ok_or(ProgramError::InvalidInstructionData)?;
+                let proof_instruction_offset =
+                    *rest.first().ok_or(ProgramError::InvalidInstructionData)?;
+                Self::CreateRegistry {
+                    owner,
+                    proof_instruction_offset: proof_instruction_offset as i8,
+                }
+            }
+            2 => {
+                let proof_instruction_offset =
+                    *rest.first().ok_or(ProgramError::InvalidInstructionData)?;
+                Self::UpdateRegistry {
+                    proof_instruction_offset: proof_instruction_offset as i8,
+                }
+            }
+            _ => return Err(ProgramError::InvalidInstructionData),
+        })
+    }
+
+    /// Packs a `RegistryInstruction` into a byte buffer.
+    pub fn pack(&self) -> Vec<u8> {
+        let mut buf = vec![];
+        match self {
+            Self::CreateRegistry {
+                owner,
+                proof_instruction_offset,
+            } => {
+                buf.push(0);
+                buf.extend_from_slice(owner.as_ref());
+                buf.extend_from_slice(&proof_instruction_offset.to_le_bytes());
+            }
+            Self::UpdateRegistry {
+                proof_instruction_offset,
+            } => {
+                buf.push(1);
+                buf.extend_from_slice(&proof_instruction_offset.to_le_bytes());
+            }
+        };
+        buf
+    }
+}

token/confidential-transfer/elgamal-registry/src/lib.rs

@@ -0,0 +1,7 @@
+mod entrypoint;
+pub mod error;
+pub mod instruction;
+pub mod processor;
+pub mod state;
+
+solana_program::declare_id!("regVYJW7tcT8zipN5YiBvHsvR5jXW1uLFxaHSbugABg");

token/confidential-transfer/elgamal-registry/src/processor.rs

@@ -0,0 +1,64 @@
+use {
+    crate::{instruction::RegistryInstruction, state::ElGamalRegistry},
+    solana_program::{
+        account_info::{next_account_info, AccountInfo},
+        entrypoint::ProgramResult,
+        program_error::ProgramError,
+        pubkey::Pubkey,
+    },
+    solana_zk_sdk::zk_elgamal_proof_program::proof_data::pubkey_validity::{
+        PubkeyValidityProofContext, PubkeyValidityProofData,
+    },
+    spl_pod::bytemuck::pod_from_bytes_mut,
+    spl_token_confidential_transfer_proof_extraction::verify_and_extract_context,
+};
+
+/// Instruction processor
+pub fn process_instruction(
+    _program_id: &Pubkey,
+    accounts: &[AccountInfo],
+    input: &[u8],
+) -> ProgramResult {
+    let instruction = RegistryInstruction::unpack(input)?;
+    let account_info_iter = &mut accounts.iter();
+    let registry_account_info = next_account_info(account_info_iter)?;
+    let registry_account_data = &mut registry_account_info.data.borrow_mut();
+    let registry_account = pod_from_bytes_mut::<ElGamalRegistry>(registry_account_data)?;
+
+    let proof_instruction_offset = match instruction {
+        RegistryInstruction::CreateRegistry {
+            owner,
+            proof_instruction_offset,
+        } => {
+            // set the owner; ElGamal pubkey is set after the zkp verification below
+            registry_account.owner = owner;
+            proof_instruction_offset
+        }
+        RegistryInstruction::UpdateRegistry {
+            proof_instruction_offset,
+        } => {
+            // check the owner; ElGamal pubkey is set after the zkp verification below
+            let owner_info = next_account_info(account_info_iter)?;
+            validate_owner(owner_info, &registry_account.owner)?;
+            proof_instruction_offset
+        }
+    };
+    // zero-knowledge proof certifies that the supplied ElGamal public key is valid
+    let proof_context = verify_and_extract_context::<
+        PubkeyValidityProofData,
+        PubkeyValidityProofContext,
+    >(account_info_iter, proof_instruction_offset as i64, None)?;
+    registry_account.elgamal_pubkey = proof_context.pubkey;
+
+    Ok(())
+}
+
+fn validate_owner(owner_info: &AccountInfo, expected_owner: &Pubkey) -> ProgramResult {
+    if expected_owner != owner_info.key {
+        return Err(ProgramError::InvalidAccountOwner);
+    }
+    if !owner_info.is_signer {
+        return Err(ProgramError::MissingRequiredSignature);
+    }
+    Ok(())
+}

token/confidential-transfer/elgamal-registry/src/state.rs

@@ -0,0 +1,16 @@
+use {
+    bytemuck::{Pod, Zeroable},
+    solana_program::pubkey::Pubkey,
+    solana_zk_sdk::encryption::pod::elgamal::PodElGamalPubkey,
+};
+
+/// ElGamal public key registry. It contains an ElGamal public key that is
+/// associated with a wallet account, but independent of any specific mint.
+#[repr(C)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Pod, Zeroable)]
+pub struct ElGamalRegistry {
+    /// The owner of the registry
+    pub owner: Pubkey,
+    /// The ElGamal public key associated with an account
+    pub elgamal_pubkey: PodElGamalPubkey,
+}