diff --git a/Cargo.toml b/Cargo.toml
index 2e5603fa..0fd36fcc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,7 +6,7 @@ homepage = "https://github.com/matter-labs/bellman"
 license = "MIT/Apache-2.0"
 name = "bellman_ce"
 repository = "https://github.com/matter-labs/bellman"
-version = "0.7.0"
+version = "0.8.0"
 edition = "2018"
 
 [lib]
@@ -33,8 +33,8 @@ tiny-keccak = {version = "1.5", optional = true}
 blake2-rfc = {version = "0.2.18", optional = true}
 blake2s_simd = {version = "0.5"}
 lazy_static = {version = "1", optional = true}
-blake2s_const = {version = "=0.7", optional = true, path = "./src/plonk/blake2_const/blake2s/"}
-hex = "0.4.3"
+blake2s_const = {version = "=0.8.0", optional = true, path = "./src/plonk/blake2_const/blake2s/"}
+hex = "0.4"
 
 [features]
 default = ["multicore", "plonk"]
diff --git a/src/plonk/better_better_cs/cs.rs b/src/plonk/better_better_cs/cs.rs
index 4b1aace3..d4c62659 100644
--- a/src/plonk/better_better_cs/cs.rs
+++ b/src/plonk/better_better_cs/cs.rs
@@ -54,7 +54,7 @@ impl SynthesisMode for SynthesisModeTesting {
 
 pub trait Circuit<E: Engine> {
     type MainGate: MainGate<E>;
-    fn synthesize<CS: ConstraintSystem<E>>(&self, cs: &mut CS) -> Result<(), SynthesisError>;
+    fn synthesize<CS: ConstraintSystem<E> + 'static>(&self, cs: &mut CS) -> Result<(), SynthesisError>;
     fn declare_used_gates() -> Result<Vec<Box<dyn GateInternal<E>>>, SynthesisError> {
         Ok(
             vec![Self::MainGate::default().into_internal()]
diff --git a/src/plonk/better_better_cs/proof/mod.rs b/src/plonk/better_better_cs/proof/mod.rs
index dbfe0d3e..44cc02db 100644
--- a/src/plonk/better_better_cs/proof/mod.rs
+++ b/src/plonk/better_better_cs/proof/mod.rs
@@ -279,6 +279,53 @@ impl<E: Engine, C: Circuit<E>> Proof<E, C> {
 
         Ok(new)
     }
+
+    pub unsafe fn redefine_circuit<C2: Circuit<E, MainGate = C::MainGate>>(mut self) -> Proof<E, C2> {
+        let mut new = Proof::<E, C2>::empty();
+
+        // it's still possible that lookups are different
+        assert_eq!(C::declare_used_gates().unwrap(), C2::declare_used_gates().unwrap());
+
+        new.n = self.n;
+        new.inputs = std::mem::replace(&mut self.inputs, vec![]);
+        new.state_polys_commitments = std::mem::replace(&mut self.state_polys_commitments, vec![]);
+        new.witness_polys_commitments = std::mem::replace(&mut self.witness_polys_commitments, vec![]);
+        new.copy_permutation_grand_product_commitment = std::mem::replace(&mut self.copy_permutation_grand_product_commitment, E::G1Affine::zero());
+
+        new.lookup_s_poly_commitment = std::mem::replace(&mut self.lookup_s_poly_commitment, None);
+        new.lookup_grand_product_commitment = std::mem::replace(&mut self.lookup_grand_product_commitment, None);
+
+        new.quotient_poly_parts_commitments = std::mem::replace(&mut self.quotient_poly_parts_commitments, vec![]);
+
+        new.state_polys_openings_at_z = std::mem::replace(&mut self.state_polys_openings_at_z, vec![]);
+        new.state_polys_openings_at_dilations = std::mem::replace(&mut self.state_polys_openings_at_dilations, vec![]);
+        new.witness_polys_openings_at_z = std::mem::replace(&mut self.witness_polys_openings_at_z, vec![]);
+        new.witness_polys_openings_at_dilations = std::mem::replace(&mut self.witness_polys_openings_at_dilations, vec![]);
+
+        new.gate_setup_openings_at_z = std::mem::replace(&mut self.gate_setup_openings_at_z, vec![]);
+        new.gate_selectors_openings_at_z = std::mem::replace(&mut self.gate_selectors_openings_at_z, vec![]);
+
+        new.copy_permutation_polys_openings_at_z = std::mem::replace(&mut self.copy_permutation_polys_openings_at_z, vec![]);
+        new.copy_permutation_grand_product_opening_at_z_omega = std::mem::replace(&mut self.copy_permutation_grand_product_opening_at_z_omega, E::Fr::zero());
+
+        new.lookup_s_poly_opening_at_z_omega = std::mem::replace(&mut self.lookup_s_poly_opening_at_z_omega, None);
+        new.lookup_grand_product_opening_at_z_omega = std::mem::replace(&mut self.lookup_grand_product_opening_at_z_omega, None);
+
+        new.lookup_t_poly_opening_at_z = std::mem::replace(&mut self.lookup_t_poly_opening_at_z, None);
+        new.lookup_t_poly_opening_at_z_omega = std::mem::replace(&mut self.lookup_t_poly_opening_at_z_omega, None);
+        
+        new.lookup_selector_poly_opening_at_z = std::mem::replace(&mut self.lookup_selector_poly_opening_at_z, None);
+        new.lookup_table_type_poly_opening_at_z = std::mem::replace(&mut self.lookup_table_type_poly_opening_at_z, None);
+
+        new.quotient_poly_opening_at_z = std::mem::replace(&mut self.quotient_poly_opening_at_z, E::Fr::zero());
+
+        new.linearization_poly_opening_at_z = std::mem::replace(&mut self.linearization_poly_opening_at_z, E::Fr::zero());
+
+        new.opening_proof_at_z = std::mem::replace(&mut self.opening_proof_at_z, E::G1Affine::zero());
+        new.opening_proof_at_z_omega = std::mem::replace(&mut self.opening_proof_at_z_omega, E::G1Affine::zero());
+
+        new
+    }
 }
 
 use super::cs::*;
diff --git a/src/plonk/better_better_cs/setup/mod.rs b/src/plonk/better_better_cs/setup/mod.rs
index f21d4cf0..e1fdf0f5 100644
--- a/src/plonk/better_better_cs/setup/mod.rs
+++ b/src/plonk/better_better_cs/setup/mod.rs
@@ -20,7 +20,7 @@ use std::io::{Read, Write};
 
 use crate::plonk::better_cs::keys::*;
 
-#[derive(Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 pub struct Setup<E: Engine, C: Circuit<E>> {
     pub n: usize,
     pub num_inputs: usize,
@@ -38,6 +38,9 @@ pub struct Setup<E: Engine, C: Circuit<E>> {
 
     pub non_residues: Vec<E::Fr>,
 
+    #[serde(skip_serializing,skip_deserializing, default)]
+    #[serde(bound(serialize = ""))]
+    #[serde(bound(deserialize = ""))]
     _marker: std::marker::PhantomData<C>
 }
 
diff --git a/src/plonk/blake2_const/blake2s/Cargo.toml b/src/plonk/blake2_const/blake2s/Cargo.toml
index 34a9f42a..72ae0c7d 100644
--- a/src/plonk/blake2_const/blake2s/Cargo.toml
+++ b/src/plonk/blake2_const/blake2s/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "blake2s_const"
-version = "0.7.0"
+version = "0.8.0"
 authors = ["Jack O'Connor"]
 description = "a pure Rust BLAKE2s implementation with dynamic SIMD"
 license = "MIT"