remove asserts; return result objects (#45)

* remove asserts; return result objects

* bump version

* clippy

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spartan"
-version = "0.4.1"
+version = "0.5.0"
 authors = ["Srinath Setty <srinath@microsoft.com>"]
 edition = "2018"
 description = "High-speed zkSNARKs without trusted setup"

README.md

@@ -1,7 +1,7 @@
 # Spartan: High-speed zkSNARKs without trusted setup
 
 ![Rust](https://github.com/microsoft/Spartan/workflows/Rust/badge.svg)
-[![](https://img.shields.io/crates/v/spartan.svg)]((https://crates.io/crates/curve25519-dalek))
+[![](https://img.shields.io/crates/v/spartan.svg)]((https://crates.io/crates/spartan))
 
 Spartan is a high-speed zero-knowledge proof system, a cryptographic primitive that enables a prover to prove a mathematical statement to a verifier without revealing anything besides the validity of the statement. This repository provides `libspartan,` a Rust library that implements a zero-knowledge succinct non-interactive argument of knowledge (zkSNARK), which is a type of zero-knowledge proof system with short proofs and fast verification times. The details of the Spartan proof system are described in our [paper](https://eprint.iacr.org/2019/550) published at [CRYPTO 2020](https://crypto.iacr.org/2020/). The security of the Spartan variant implemented in this library is based on the discrete logarithm problem in the random oracle model.
 
@@ -16,7 +16,7 @@ We now highlight Spartan's distinctive features.
 
 * **General-purpose:** Spartan produces proofs for arbitrary NP statements. `libspartan` supports NP statements expressed as rank-1 constraint satisfiability (R1CS) instances, a popular language for which there exists efficient transformations and compiler toolchains from high-level programs of interest.
 
-* **Sub-linear verification costs and linear-time proving costs:** Spartan is the first transparent proof system with sub-linear verification costs for arbitrary NP statements (e.g., R1CS). Spartan also features a linear-time prover, a property that has remained elusive for nearly all zkSNARKs in the literature.
+* **Sub-linear verification costs:** Spartan is the first transparent proof system with sub-linear verification costs for arbitrary NP statements (e.g., R1CS).
 
 * **Standardized security:** Spartan's security relies on the hardness of computing discrete logarithms (a standard cryptographic assumption) in the random oracle model. `libspartan` uses `ristretto255`, a prime-order group abstraction atop `curve25519` (a high-speed elliptic curve). We use [`curve25519-dalek`](https://docs.rs/curve25519-dalek) for arithmetic over `ristretto255`. 
 

profiler/nizk.rs

@@ -10,7 +10,7 @@ use merlin::Transcript;
 
 fn print(msg: &str) {
   let star = "* ";
-  println!("{:indent$}{}{}", "", star, msg.to_string(), indent = 2);
+  println!("{:indent$}{}{}", "", star, msg, indent = 2);
 }
 
 pub fn main() {

profiler/snark.rs

@@ -9,7 +9,7 @@ use merlin::Transcript;
 
 fn print(msg: &str) {
   let star = "* ";
-  println!("{:indent$}{}{}", "", star, msg.to_string(), indent = 2);
+  println!("{:indent$}{}{}", "", star, msg, indent = 2);
 }
 
 pub fn main() {

src/lib.rs

@@ -441,17 +441,14 @@ impl SNARK {
     Ar.append_to_transcript(b"Ar_claim", transcript);
     Br.append_to_transcript(b"Br_claim", transcript);
     Cr.append_to_transcript(b"Cr_claim", transcript);
-    assert!(self
-      .r1cs_eval_proof
-      .verify(
-        &comm.comm,
-        &rx,
-        &ry,
-        &self.inst_evals,
-        &gens.gens_r1cs_eval,
-        transcript
-      )
-      .is_ok());
+    self.r1cs_eval_proof.verify(
+      &comm.comm,
+      &rx,
+      &ry,
+      &self.inst_evals,
+      &gens.gens_r1cs_eval,
+      transcript,
+    )?;
     timer_eval_proof.stop();
     timer_verify.stop();
     Ok(())

src/nizk/bullet.rs

@@ -231,7 +231,7 @@ impl BulletReductionProof {
 /// Panics if the lengths of \\(\mathbf{a}\\) and \\(\mathbf{b}\\) are not equal.
 pub fn inner_product(a: &[Scalar], b: &[Scalar]) -> Scalar {
   assert!(
-    !(a.len() != b.len()),
+    a.len() == b.len(),
     "inner_product(a,b): lengths of vectors do not match"
   );
   let mut out = Scalar::zero();

src/r1csinstance.rs

@@ -336,18 +336,13 @@ impl R1CSEvalProof {
     gens: &R1CSCommitmentGens,
     transcript: &mut Transcript,
   ) -> Result<(), ProofVerifyError> {
-    assert!(self
-      .proof
-      .verify(
-        &comm.comm,
-        rx,
-        ry,
-        &[evals.0, evals.1, evals.2],
-        &gens.gens,
-        transcript
-      )
-      .is_ok());
-
-    Ok(())
+    self.proof.verify(
+      &comm.comm,
+      rx,
+      ry,
+      &[evals.0, evals.1, evals.2],
+      &gens.gens,
+      transcript,
+    )
   }
 }

src/r1csproof.rs

@@ -382,18 +382,14 @@ impl R1CSProof {
     let (comm_Az_claim, comm_Bz_claim, comm_Cz_claim, comm_prod_Az_Bz_claims) = &self.claims_phase2;
     let (pok_Cz_claim, proof_prod) = &self.pok_claims_phase2;
 
-    assert!(pok_Cz_claim
-      .verify(&gens.gens_sc.gens_1, transcript, comm_Cz_claim)
-      .is_ok());
-    assert!(proof_prod
-      .verify(
-        &gens.gens_sc.gens_1,
-        transcript,
-        comm_Az_claim,
-        comm_Bz_claim,
-        comm_prod_Az_Bz_claims
-      )
-      .is_ok());
+    pok_Cz_claim.verify(&gens.gens_sc.gens_1, transcript, comm_Cz_claim)?;
+    proof_prod.verify(
+      &gens.gens_sc.gens_1,
+      transcript,
+      comm_Az_claim,
+      comm_Bz_claim,
+      comm_prod_Az_Bz_claims,
+    )?;
 
     comm_Az_claim.append_to_transcript(b"comm_Az_claim", transcript);
     comm_Bz_claim.append_to_transcript(b"comm_Bz_claim", transcript);
@@ -408,15 +404,12 @@ impl R1CSProof {
     .compress();
 
     // verify proof that expected_claim_post_phase1 == claim_post_phase1
-    assert!(self
-      .proof_eq_sc_phase1
-      .verify(
-        &gens.gens_sc.gens_1,
-        transcript,
-        &expected_claim_post_phase1,
-        &comm_claim_post_phase1,
-      )
-      .is_ok());
+    self.proof_eq_sc_phase1.verify(
+      &gens.gens_sc.gens_1,
+      transcript,
+      &expected_claim_post_phase1,
+      &comm_claim_post_phase1,
+    )?;
 
     // derive three public challenges and then derive a joint claim
     let r_A = transcript.challenge_scalar(b"challenege_Az");
@@ -447,16 +440,13 @@ impl R1CSProof {
     )?;
 
     // verify Z(ry) proof against the initial commitment
-    assert!(self
-      .proof_eval_vars_at_ry
-      .verify(
-        &gens.gens_pc,
-        transcript,
-        &ry[1..].to_vec(),
-        &self.comm_vars_at_ry,
-        &self.comm_vars
-      )
-      .is_ok());
+    self.proof_eval_vars_at_ry.verify(
+      &gens.gens_pc,
+      transcript,
+      &ry[1..].to_vec(),
+      &self.comm_vars_at_ry,
+      &self.comm_vars,
+    )?;
 
     let poly_input_eval = {
       // constant term
@@ -484,15 +474,12 @@ impl R1CSProof {
     let expected_claim_post_phase2 =
       ((r_A * eval_A_r + r_B * eval_B_r + r_C * eval_C_r) * comm_eval_Z_at_ry).compress();
     // verify proof that expected_claim_post_phase1 == claim_post_phase1
-    assert!(self
-      .proof_eq_sc_phase2
-      .verify(
-        &gens.gens_sc.gens_1,
-        transcript,
-        &expected_claim_post_phase2,
-        &comm_claim_post_phase2,
-      )
-      .is_ok());
+    self.proof_eq_sc_phase2.verify(
+      &gens.gens_sc.gens_1,
+      transcript,
+      &expected_claim_post_phase2,
+      &comm_claim_post_phase2,
+    )?;
 
     Ok((rx, ry))
   }

src/sparse_mlpoly.rs

@@ -178,11 +178,8 @@ impl DerefsEvalProof {
 
     // decommit the joint polynomial at r_joint
     joint_claim_eval.append_to_transcript(b"joint_claim_eval", transcript);
-    assert!(proof
-      .verify_plain(gens, transcript, &r_joint, &joint_claim_eval, comm)
-      .is_ok());
 
-    Ok(())
+    proof.verify_plain(gens, transcript, &r_joint, &joint_claim_eval, comm)
   }
 
   // verify evaluations of both polynomials at r
@@ -200,7 +197,7 @@ impl DerefsEvalProof {
     evals.extend(eval_col_ops_val_vec);
     evals.resize(evals.len().next_power_of_two(), Scalar::zero());
 
-    assert!(DerefsEvalProof::verify_single(
+    DerefsEvalProof::verify_single(
       &self.proof_derefs,
       &comm.comm_ops_val,
       r,
@@ -208,9 +205,6 @@ impl DerefsEvalProof {
       gens,
       transcript,
     )
-    .is_ok());
-
-    Ok(())
   }
 }
 
@@ -910,17 +904,14 @@ impl HashLayerProof {
     // verify derefs at rand_ops
     let (eval_row_ops_val, eval_col_ops_val) = &self.eval_derefs;
     assert_eq!(eval_row_ops_val.len(), eval_col_ops_val.len());
-    assert!(self
-      .proof_derefs
-      .verify(
-        rand_ops,
-        eval_row_ops_val,
-        eval_col_ops_val,
-        &gens.gens_derefs,
-        comm_derefs,
-        transcript
-      )
-      .is_ok());
+    self.proof_derefs.verify(
+      rand_ops,
+      eval_row_ops_val,
+      eval_col_ops_val,
+      &gens.gens_derefs,
+      comm_derefs,
+      transcript,
+    )?;
 
     // verify the decommitments used in evaluation sum-check
     let eval_val_vec = &self.eval_val;
@@ -990,20 +981,17 @@ impl HashLayerProof {
     let mut r_joint_mem = challenges_mem;
     r_joint_mem.extend(rand_mem);
     joint_claim_eval_mem.append_to_transcript(b"joint_claim_eval_mem", transcript);
-    assert!(self
-      .proof_mem
-      .verify_plain(
-        &gens.gens_mem,
-        transcript,
-        &r_joint_mem,
-        &joint_claim_eval_mem,
-        &comm.comm_comb_mem
-      )
-      .is_ok());
+    self.proof_mem.verify_plain(
+      &gens.gens_mem,
+      transcript,
+      &r_joint_mem,
+      &joint_claim_eval_mem,
+      &comm.comm_comb_mem,
+    )?;
 
     // verify the claims from the product layer
     let (eval_ops_addr, eval_read_ts, eval_audit_ts) = &self.eval_row;
-    assert!(HashLayerProof::verify_helper(
+    HashLayerProof::verify_helper(
       &(rand_mem, rand_ops),
       claims_row,
       eval_row_ops_val,
@@ -1013,11 +1001,10 @@ impl HashLayerProof {
       rx,
       r_hash,
       r_multiset_check,
-    )
-    .is_ok());
+    )?;
 
     let (eval_ops_addr, eval_read_ts, eval_audit_ts) = &self.eval_col;
-    assert!(HashLayerProof::verify_helper(
+    HashLayerProof::verify_helper(
       &(rand_mem, rand_ops),
       claims_col,
       eval_col_ops_val,
@@ -1027,8 +1014,7 @@ impl HashLayerProof {
       ry,
       r_hash,
       r_multiset_check,
-    )
-    .is_ok());
+    )?;
 
     timer.stop();
     Ok(())
@@ -1562,22 +1548,17 @@ impl SparseMatPolyEvalProof {
     // produce a random element from the transcript for hash function
     let r_mem_check = transcript.challenge_vector(b"challenge_r_hash", 2);
 
-    assert!(self
-      .poly_eval_network_proof
-      .verify(
-        comm,
-        &self.comm_derefs,
-        evals,
-        gens,
-        &rx_ext,
-        &ry_ext,
-        &(r_mem_check[0], r_mem_check[1]),
-        nz,
-        transcript,
-      )
-      .is_ok());
-
-    Ok(())
+    self.poly_eval_network_proof.verify(
+      comm,
+      &self.comm_derefs,
+      evals,
+      gens,
+      &rx_ext,
+      &ry_ext,
+      &(r_mem_check[0], r_mem_check[1]),
+      nz,
+      transcript,
+    )
   }
 }
 

src/sumcheck.rs

@@ -168,7 +168,9 @@ impl ZKSumcheckInstanceProof {
           )
           .is_ok()
       };
-      assert!(res);
+      if !res {
+        return Err(ProofVerifyError::InternalError);
+      }
 
       r.push(r_i);
     }