forbid 0-bit range proof verification

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

@@ -205,7 +205,7 @@ impl InnerProductProof {
         transcript: &mut Transcript,
     ) -> Result<(Vec<Scalar>, Vec<Scalar>, Vec<Scalar>), RangeProofVerificationError> {
         let lg_n = self.L_vec.len();
-        if lg_n >= 32 {
+        if lg_n == 0 || lg_n >= 32 {
             // 4 billion multiplications should be enough for anyone
             // and this check prevents overflow in 1<<lg_n below.
             return Err(RangeProofVerificationError::InvalidBitSize);