feat: add errors for range proof module

zk-token-sdk/src/errors.rs

@@ -5,14 +5,6 @@ use thiserror::Error;
 pub enum ProofError {
     #[error("proof failed to verify")]
     VerificationError,
-    #[error("malformed proof")]
-    FormatError,
-    #[error("number of blinding factors do not match the number of values")]
-    WrongNumBlindingFactors,
-    #[error("attempted to create a proof with bitsize other than \\(8\\), \\(16\\), \\(32\\), or \\(64\\)")]
-    InvalidBitsize,
-    #[error("insufficient generators for the proof")]
-    InvalidGeneratorsLength,
     #[error(
         "`zk_token_elgamal::pod::ElGamalCiphertext` contains invalid ElGamalCiphertext ciphertext"
     )]

zk-token-sdk/src/range_proof/errors.rs

@@ -0,0 +1,16 @@
+//! Errors related to proving and verifying proofs.
+use thiserror::Error;
+
+#[derive(Error, Clone, Debug, Eq, PartialEq)]
+pub enum ProofError {
+    #[error("the required algebraic relation does not hold")]
+    AlgebraicRelationError,
+    #[error("malformed proof")]
+    FormatError,
+    #[error("attempted to create a proof with a non-power-of-two bitsize")]
+    InvalidBitsize,
+    #[error("insufficient generators for the proof")]
+    InvalidGeneratorsLength,
+    #[error("number of blinding factors do not match the number of values")]
+    WrongNumBlindingFactors,
+}

zk-token-sdk/src/range_proof/mod.rs

@@ -24,6 +24,7 @@ use {
 pub mod generators;
 pub mod inner_product;
 pub mod util;
+pub mod errors;
 
 #[allow(non_snake_case)]
 #[derive(Clone)]
@@ -222,23 +223,6 @@ impl RangeProof {
         bit_lengths: Vec<usize>,
         transcript: &mut Transcript,
     ) -> Result<(), ProofError> {
-        if self
-            .verify_challenges(comms, bit_lengths, transcript)
-            .is_ok()
-        {
-            Ok(())
-        } else {
-            Err(ProofError::VerificationError)
-        }
-    }
-
-    #[allow(clippy::many_single_char_names)]
-    pub fn verify_challenges(
-        &self,
-        comms: Vec<&CompressedRistretto>,
-        bit_lengths: Vec<usize>,
-        transcript: &mut Transcript,
-    ) -> Result<(Scalar, Scalar), ProofError> {
         let G = PedersenBase::default().G;
         let H = PedersenBase::default().H;
 
@@ -246,6 +230,10 @@ impl RangeProof {
         let nm: usize = bit_lengths.iter().sum();
         let bp_gens = BulletproofGens::new(nm);
 
+        if !nm.is_power_of_two() {
+            return Err(ProofError::InvalidBitsize);
+        }
+
         if !(nm == 8 || nm == 16 || nm == 32 || nm == 64 || nm == 128) {
             return Err(ProofError::InvalidBitsize);
         }