Add feature-gated serde support for Participant/ThresholdParams

These don't have secret data yet sometimes have value to be communicated.

Cargo.lock

@@ -1699,6 +1699,7 @@ dependencies = [
  "multiexp",
  "rand_core 0.6.4",
  "schnorr-signatures",
+ "serde",
  "thiserror",
  "zeroize",
 ]

crypto/dkg/Cargo.toml

@@ -19,6 +19,8 @@ rand_core = "0.6"
 
 zeroize = { version = "^1.5", features = ["zeroize_derive"] }
 
+serde = { version = "1", features = ["derive"], optional = true }
+
 transcript = { package = "flexible-transcript", path = "../transcript", version = "0.2", features = ["recommended"] }
 chacha20 = { version = "0.9", features = ["zeroize"] }
 
@@ -33,4 +35,5 @@ dleq = { path = "../dleq", version = "0.2", features = ["serialize"] }
 ciphersuite = { path = "../ciphersuite", version = "0.1", features = ["std", "ristretto"] }
 
 [features]
+serde = ["dep:serde"]
 tests = []

crypto/dkg/src/lib.rs

@@ -38,6 +38,7 @@ pub mod tests;
 
 /// The ID of a participant, defined as a non-zero u16.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Zeroize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Participant(pub(crate) u16);
 impl Participant {
   pub fn new(i: u16) -> Option<Participant> {
@@ -123,6 +124,7 @@ pub(crate) fn validate_map<T, B: Clone + PartialEq + Eq + Debug>(
 /// Parameters for a multisig.
 // These fields should not be made public as they should be static
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Zeroize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct ThresholdParams {
   /// Participants needed to sign on behalf of the group.
   t: u16,