Use the serde_as crate to serialize potentially big arrays

Cargo.toml

@@ -16,11 +16,13 @@ rand_core = "0.6.3"
 curv-kzen = { git = "https://github.com/ZenGo-X/curv", branch = "ffts" }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-criterion = "0.3"
+serde_with = "1.11.0"
 
 [dev-dependencies]
 quickcheck = "0.9"
 quickcheck_macros = "0.9"
+criterion = "0.3"
+
 
 [[bench]]
 name = "dpf_bench"

src/keygen.rs

@@ -10,18 +10,24 @@ use curv::cryptographic_primitives::secret_sharing::{
 use curv::elliptic::curves::{Point, Scalar, Secp256k1};
 use curv::BigInt;
 use serde::{Deserialize, Serialize};
+use serde_with::serde_as;
 use std::convert::TryInto;
 use std::ops::{Add, Neg};
 use std::ptr;
 use std::{fs, mem};
 
+#[serde_as]
 #[derive(Debug, Serialize, Deserialize)]
 pub struct LongTermKey {
     pub alpha_i: Scalar<Secp256k1>,
     pub sk_i: Scalar<Secp256k1>,
+    #[serde_as(as = "[[_; t]; c]")]
     pub w_i: [[BigInt; t]; c],
+    #[serde_as(as = "[[_; t]; c]")]
     pub eta_i: [[BigInt; t]; c],
+    #[serde_as(as = "[[_; t]; c]")]
     pub beta_i: [[Scalar<Secp256k1>; t]; c],
+    #[serde_as(as = "[[_; t]; c]")]
     pub gamma_i: [[Scalar<Secp256k1>; t]; c],
     pub u_i_0: [[DSPF; (n - 1)]; c],
     pub u_i_1: [[DSPF; (n - 1)]; c],