chore: encapsulate abstraction leaks from bb into new crate (#2747)

Cargo.toml

@@ -12,7 +12,8 @@ members = [
     "compiler/utils/arena",
     "compiler/utils/iter-extended",
     # Crates related to tooling built ontop of the Noir compiler
-    "tooling/acvm_backend_barretenberg",
+    "tooling/backend_interface",
+    "tooling/bb_abstraction_leaks",
     "tooling/nargo",
     "tooling/nargo_cli",
     "tooling/nargo_toml",
@@ -41,6 +42,7 @@ nargo_cli = { path = "tooling/nargo_cli" }
 nargo_toml = { path = "tooling/nargo_toml" }
 noir_lsp = { path = "tooling/lsp" }
 noirc_abi = { path = "tooling/noirc_abi" }
+bb_abstraction_leaks = { path = "tooling/bb_abstraction_leaks" }
 noirc_driver = { path = "compiler/noirc_driver" }
 noirc_errors = { path = "compiler/noirc_errors" }
 noirc_evaluator = { path = "compiler/noirc_evaluator" }

tooling/acvm_backend_barretenberg/Cargo.toml → tooling/backend_interface/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
-name = "acvm-backend-barretenberg"
-description = "An ACVM backend which allows proving/verifying ACIR circuits against Aztec Lab's Barretenberg library."
+name = "backend-interface"
+description = "The definition of the backend CLI interface which Nargo uses for proving/verifying ACIR circuits."
 version = "0.11.0"
 authors.workspace = true
 edition.workspace = true
@@ -15,6 +15,7 @@ dirs.workspace = true
 thiserror.workspace = true
 serde.workspace = true
 serde_json.workspace = true
+bb_abstraction_leaks.workspace = true
 
 tempfile = "3.6.0"
 

tooling/acvm_backend_barretenberg/src/lib.rs → tooling/backend_interface/src/lib.rs

@@ -9,10 +9,10 @@ mod proof_system;
 mod smart_contract;
 
 use acvm::acir::circuit::Opcode;
+use bb_abstraction_leaks::ACVM_BACKEND_BARRETENBERG;
 pub use download::download_backend;
 
 const BACKENDS_DIR: &str = ".nargo/backends";
-pub const ACVM_BACKEND_BARRETENBERG: &str = "acvm-backend-barretenberg";
 
 pub fn backends_directory() -> PathBuf {
     let home_directory = dirs::home_dir().unwrap();
@@ -65,6 +65,10 @@ impl Backend {
         Backend { name, binary_path }
     }
 
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
     fn binary_path(&self) -> &PathBuf {
         &self.binary_path
     }
@@ -77,7 +81,7 @@ impl Backend {
             if self.name == ACVM_BACKEND_BARRETENBERG {
                 // If we're trying to use barretenberg, automatically go and install it.
                 let bb_url = std::env::var("BB_BINARY_URL")
-                    .unwrap_or_else(|_| env!("BB_BINARY_URL").to_string());
+                    .unwrap_or_else(|_| bb_abstraction_leaks::BB_DOWNLOAD_URL.to_owned());
                 download_backend(&bb_url, binary_path)?;
                 return Ok(binary_path);
             }

tooling/acvm_backend_barretenberg/src/proof_system.rs → tooling/backend_interface/src/proof_system.rs

@@ -63,15 +63,10 @@ impl Backend {
         }
         .run(binary_path)?;
 
-        // Barretenberg return the proof prepended with the public inputs.
-        //
-        // This is not how the API expects the proof to be formatted,
-        // so we remove the public inputs from the proof.
-        //
-        // TODO: As noted in the verification procedure, this is an abstraction leak
-        // TODO: and will need modifications to barretenberg
-        let proof =
-            remove_public_inputs(circuit.public_inputs().0.len(), &proof_with_public_inputs);
+        let proof = bb_abstraction_leaks::remove_public_inputs(
+            circuit.public_inputs().0.len(),
+            &proof_with_public_inputs,
+        );
         Ok(proof)
     }
 
@@ -92,12 +87,10 @@ impl Backend {
         let flattened_public_inputs: Vec<FieldElement> =
             public_inputs.into_iter().map(|(_, el)| el).collect();
 
-        // Barretenberg expects the proof to be prepended with the public inputs.
-        //
-        // TODO: This is an abstraction leak and barretenberg's API should accept the public inputs
-        // TODO: separately and then prepend them internally
-        let proof_with_public_inputs =
-            prepend_public_inputs(proof.to_vec(), flattened_public_inputs.to_vec());
+        let proof_with_public_inputs = bb_abstraction_leaks::prepend_public_inputs(
+            proof.to_vec(),
+            flattened_public_inputs.to_vec(),
+        );
 
         // Create a temporary file for the proof
         let proof_path = temp_directory.join("proof").with_extension("proof");
@@ -139,26 +132,6 @@ pub(super) fn write_to_file(bytes: &[u8], path: &Path) -> String {
     }
 }
 
-/// Removes the public inputs which are prepended to a proof by Barretenberg.
-fn remove_public_inputs(num_pub_inputs: usize, proof: &[u8]) -> Vec<u8> {
-    // Barretenberg prepends the public inputs onto the proof so we need to remove
-    // the first `num_pub_inputs` field elements.
-    let num_bytes_to_remove = num_pub_inputs * (FieldElement::max_num_bytes() as usize);
-    proof[num_bytes_to_remove..].to_vec()
-}
-
-/// Prepends a set of public inputs to a proof.
-fn prepend_public_inputs(proof: Vec<u8>, public_inputs: Vec<FieldElement>) -> Vec<u8> {
-    if public_inputs.is_empty() {
-        return proof;
-    }
-
-    let public_inputs_bytes =
-        public_inputs.into_iter().flat_map(|assignment| assignment.to_be_bytes());
-
-    public_inputs_bytes.chain(proof).collect()
-}
-
 // TODO: See nargo/src/artifacts/mod.rs
 // TODO: This method should live in ACVM and be the default method for serializing/deserializing circuits
 pub(super) fn serialize_circuit(circuit: &Circuit) -> Vec<u8> {

tooling/acvm_backend_barretenberg/src/smart_contract.rs → tooling/backend_interface/src/smart_contract.rs

@@ -6,9 +6,6 @@ use crate::{
 use acvm::acir::circuit::Circuit;
 use tempfile::tempdir;
 
-/// Embed the Solidity verifier file
-const ULTRA_VERIFIER_CONTRACT: &str = include_str!("contract.sol");
-
 impl Backend {
     pub fn eth_contract(&self, circuit: &Circuit) -> Result<String, BackendError> {
         let binary_path = self.assert_binary_exists()?;
@@ -32,11 +29,7 @@ impl Backend {
         }
         .run(binary_path)?;
 
-        let verification_key_library =
-            ContractCommand { crs_path: self.crs_directory(), vk_path }.run(binary_path)?;
-
-        drop(temp_directory);
-        Ok(format!("{verification_key_library}{ULTRA_VERIFIER_CONTRACT}"))
+        ContractCommand { crs_path: self.crs_directory(), vk_path }.run(binary_path)
     }
 }
 
@@ -67,9 +60,7 @@ mod tests {
 
         let contract = get_mock_backend()?.eth_contract(&circuit)?;
 
-        assert!(contract.contains("contract BaseUltraVerifier"));
-        assert!(contract.contains("contract UltraVerifier"));
-        assert!(contract.contains("library UltraVerificationKey"));
+        assert!(contract.contains("contract VerifierContract"));
 
         Ok(())
     }

tooling/acvm_backend_barretenberg/test-binaries/mock_backend/src/contract_cmd.rs → tooling/backend_interface/test-binaries/mock_backend/src/contract_cmd.rs

@@ -17,9 +17,5 @@ pub(crate) struct ContractCommand {
 pub(crate) fn run(args: ContractCommand) {
     assert!(args.vk_path.is_file(), "Could not find vk file at provided path");
 
-    std::io::stdout()
-        .write_all(
-            b"contract BaseUltraVerifier contract UltraVerifier library UltraVerificationKey",
-        )
-        .unwrap();
+    std::io::stdout().write_all(b"contract VerifierContract {}").unwrap();
 }

tooling/bb_abstraction_leaks/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "bb_abstraction_leaks"
+description = "A crate which encapsulates knowledge about Barretenberg which is currently leaking into Nargo"
+version = "0.11.0"
+authors.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+acvm.workspace = true
+
+[build-dependencies]
+build-target = "0.4.0"
+const_format = "0.2.30"

tooling/bb_abstraction_leaks/src/lib.rs

@@ -0,0 +1,34 @@
+#![warn(unused_crate_dependencies, unused_extern_crates)]
+#![warn(unreachable_pub)]
+
+use acvm::FieldElement;
+
+pub const ACVM_BACKEND_BARRETENBERG: &str = "acvm-backend-barretenberg";
+pub const BB_DOWNLOAD_URL: &str = env!("BB_BINARY_URL");
+
+/// Embed the Solidity verifier file
+const ULTRA_VERIFIER_CONTRACT: &str = include_str!("contract.sol");
+
+pub fn complete_barretenberg_verifier_contract(contract: String) -> String {
+    format!("{contract}{ULTRA_VERIFIER_CONTRACT}")
+}
+
+/// Removes the public inputs which are prepended to a proof by Barretenberg.
+pub fn remove_public_inputs(num_pub_inputs: usize, proof: &[u8]) -> Vec<u8> {
+    // Barretenberg prepends the public inputs onto the proof so we need to remove
+    // the first `num_pub_inputs` field elements.
+    let num_bytes_to_remove = num_pub_inputs * (FieldElement::max_num_bytes() as usize);
+    proof[num_bytes_to_remove..].to_vec()
+}
+
+/// Prepends a set of public inputs to a proof.
+pub fn prepend_public_inputs(proof: Vec<u8>, public_inputs: Vec<FieldElement>) -> Vec<u8> {
+    if public_inputs.is_empty() {
+        return proof;
+    }
+
+    let public_inputs_bytes =
+        public_inputs.into_iter().flat_map(|assignment| assignment.to_be_bytes());
+
+    public_inputs_bytes.chain(proof).collect()
+}

tooling/nargo_cli/Cargo.toml

@@ -50,7 +50,8 @@ color-eyre = "0.6.2"
 tokio = { version = "1.0", features = ["io-std"] }
 
 # Backends
-acvm-backend-barretenberg = { path = "../acvm_backend_barretenberg" }
+backend-interface = { path = "../backend_interface" }
+bb_abstraction_leaks.workspace = true
 
 [target.'cfg(not(unix))'.dependencies]
 tokio-util = { version = "0.7.8", features = ["compat"] }

tooling/nargo_cli/src/backends.rs

@@ -1,7 +1,7 @@
 use std::path::PathBuf;
 
-use acvm_backend_barretenberg::backends_directory;
-pub(crate) use acvm_backend_barretenberg::Backend;
+use backend_interface::backends_directory;
+pub(crate) use backend_interface::Backend;
 
 fn active_backend_file_path() -> PathBuf {
     backends_directory().join(".selected_backend")

tooling/nargo_cli/src/cli/backend_cmd/install_cmd.rs

@@ -1,6 +1,6 @@
 use clap::Args;
 
-use acvm_backend_barretenberg::{backends_directory, download_backend};
+use backend_interface::{backends_directory, download_backend};
 
 use crate::errors::{BackendError, CliError};
 

tooling/nargo_cli/src/cli/backend_cmd/ls_cmd.rs

@@ -1,4 +1,4 @@
-use acvm_backend_barretenberg::backends_directory;
+use backend_interface::backends_directory;
 use clap::Args;
 
 use crate::errors::CliError;

tooling/nargo_cli/src/cli/backend_cmd/uninstall_cmd.rs

@@ -1,6 +1,6 @@
 use clap::Args;
 
-use acvm_backend_barretenberg::backends_directory;
+use backend_interface::backends_directory;
 
 use crate::{
     backends::{

tooling/nargo_cli/src/cli/codegen_verifier_cmd.rs

@@ -10,6 +10,7 @@ use crate::errors::CliError;
 
 use acvm::acir::circuit::Opcode;
 use acvm::Language;
+use bb_abstraction_leaks::ACVM_BACKEND_BARRETENBERG;
 use clap::Args;
 use nargo::artifacts::program::PreprocessedProgram;
 use nargo::package::Package;
@@ -91,7 +92,12 @@ fn smart_contract_for_package(
         }
     };
 
-    let smart_contract_string = backend.eth_contract(&preprocessed_program.bytecode)?;
+    let mut smart_contract_string = backend.eth_contract(&preprocessed_program.bytecode)?;
+
+    if backend.name() == ACVM_BACKEND_BARRETENBERG {
+        smart_contract_string =
+            bb_abstraction_leaks::complete_barretenberg_verifier_contract(smart_contract_string);
+    }
 
     Ok(smart_contract_string)
 }

tooling/nargo_cli/src/cli/compile_cmd.rs

@@ -2,7 +2,7 @@ use std::path::Path;
 
 use acvm::acir::circuit::Opcode;
 use acvm::Language;
-use acvm_backend_barretenberg::BackendOpcodeSupport;
+use backend_interface::BackendOpcodeSupport;
 use fm::FileManager;
 use iter_extended::vecmap;
 use nargo::artifacts::contract::PreprocessedContract;

tooling/nargo_cli/src/cli/info_cmd.rs

@@ -1,5 +1,5 @@
 use acvm::Language;
-use acvm_backend_barretenberg::BackendError;
+use backend_interface::BackendError;
 use clap::Args;
 use iter_extended::vecmap;
 use nargo::package::Package;

tooling/nargo_cli/src/errors.rs

@@ -70,7 +70,7 @@ pub(crate) enum CliError {
 
     /// Error related to communication with backend.
     #[error(transparent)]
-    BackendCommunicationError(#[from] acvm_backend_barretenberg::BackendError),
+    BackendCommunicationError(#[from] backend_interface::BackendError),
 }
 
 #[derive(Debug, thiserror::Error)]