constraint chunk_index < total_chunks

privacy-scaling-explorations · Dec 7, 2023 · 5754924 · 5754924
1 parent 7d30826
commit 5754924
Showing 1 changed file with 13 additions and 0 deletions.
diff --git a/zkevm-circuits/src/util/chunkctx_config.rs b/zkevm-circuits/src/util/chunkctx_config.rs
@@ -1,6 +1,7 @@
 use bus_mapping::circuit_input_builder::ChunkContext;
 use gadgets::{
     is_zero::{IsZeroChip, IsZeroConfig, IsZeroInstruction},
+    less_than::LtChip,
     util::Expr,
 };
 use halo2_proofs::{
@@ -77,6 +78,18 @@ impl<F: Field> ChunkContextConfig<F> {
             });
         });
 
+        // assume max total_chunks < 2^8
+        let is_chunk_index_lt_total_chunks = LtChip::<_, 1>::configure(
+            meta,
+            |meta| meta.query_selector(q_chunk_context),
+            |meta| meta.query_advice(chunk_index, Rotation::cur()),
+            |meta| meta.query_advice(total_chunks, Rotation::cur()),
+        );
+
+        meta.create_gate("chunk_index < total_chunks", |meta| {
+            [1.expr() - is_chunk_index_lt_total_chunks.is_lt(meta, None)]
+        });
+
         let is_first_chunk = IsZeroChip::configure(
             meta,
             |meta| meta.query_selector(q_chunk_context),