shielded-pool: use typed Nullifier in EventSpend

This is technically a breaking change but I think we should pretend it isn't, since it only affects events, and we never parse the events. So cleaning it up now is an opportunity to do a fix with minimal breakage.

crates/core/component/shielded-pool/src/event.rs

@@ -9,7 +9,7 @@ use crate::NotePayload;
 
 pub fn spend(nullifier: &Nullifier) -> EventSpend {
     EventSpend {
-        nullifier: nullifier.to_bytes().to_vec(),
+        nullifier: Some((*nullifier).into()),
     }
 }
 

crates/proto/src/event.rs

@@ -64,14 +64,17 @@ mod tests {
     #[test]
     fn event_round_trip() {
         use super::*;
+        use crate::core::component::sct::v1alpha1::Nullifier;
         use crate::core::component::shielded_pool::v1alpha1::{EventOutput, EventSpend};
         use crate::crypto::tct::v1alpha1::StateCommitment;
 
         let proto_spend = EventSpend {
-            nullifier: vec![
-                148, 190, 149, 23, 86, 113, 152, 145, 104, 242, 142, 162, 233, 239, 137, 141, 140,
-                164, 180, 98, 154, 55, 168, 255, 163, 228, 179, 176, 26, 25, 219, 211,
-            ],
+            nullifier: Some(Nullifier {
+                inner: vec![
+                    148, 190, 149, 23, 86, 113, 152, 145, 104, 242, 142, 162, 233, 239, 137, 141,
+                    140, 164, 180, 98, 154, 55, 168, 255, 163, 228, 179, 176, 26, 25, 219, 211,
+                ],
+            }),
         };
 
         let abci_spend = proto_spend.into_event();
@@ -80,7 +83,7 @@ mod tests {
             "penumbra.core.component.shielded_pool.v1alpha1.EventSpend",
             vec![abci::EventAttribute {
                 key: "nullifier".to_string(),
-                value: "\"lL6VF1ZxmJFo8o6i6e+JjYyktGKaN6j/o+SzsBoZ29M=\"".to_string(),
+                value: "{\"inner\":\"lL6VF1ZxmJFo8o6i6e+JjYyktGKaN6j/o+SzsBoZ29M=\"}".to_string(),
                 index: true,
             }],
         );

crates/proto/src/gen/penumbra.core.component.shielded_pool.v1alpha1.rs

@@ -159,8 +159,8 @@ impl ::prost::Name for Spend {
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct EventSpend {
-    #[prost(bytes = "vec", tag = "1")]
-    pub nullifier: ::prost::alloc::vec::Vec<u8>,
+    #[prost(message, optional, tag = "1")]
+    pub nullifier: ::core::option::Option<super::super::sct::v1alpha1::Nullifier>,
 }
 impl ::prost::Name for EventSpend {
     const NAME: &'static str = "EventSpend";

crates/proto/src/gen/penumbra.core.component.shielded_pool.v1alpha1.serde.rs

@@ -300,13 +300,12 @@ impl serde::Serialize for EventSpend {
     {
         use serde::ser::SerializeStruct;
         let mut len = 0;
-        if !self.nullifier.is_empty() {
+        if self.nullifier.is_some() {
             len += 1;
         }
         let mut struct_ser = serializer.serialize_struct("penumbra.core.component.shielded_pool.v1alpha1.EventSpend", len)?;
-        if !self.nullifier.is_empty() {
-            #[allow(clippy::needless_borrow)]
-            struct_ser.serialize_field("nullifier", pbjson::private::base64::encode(&self.nullifier).as_str())?;
+        if let Some(v) = self.nullifier.as_ref() {
+            struct_ser.serialize_field("nullifier", v)?;
         }
         struct_ser.end()
     }
@@ -372,14 +371,12 @@ impl<'de> serde::Deserialize<'de> for EventSpend {
                             if nullifier__.is_some() {
                                 return Err(serde::de::Error::duplicate_field("nullifier"));
                             }
-                            nullifier__ = 
-                                Some(map_.next_value::<::pbjson::private::BytesDeserialize<_>>()?.0)
-                            ;
+                            nullifier__ = map_.next_value()?;
                         }
                     }
                 }
                 Ok(EventSpend {
-                    nullifier: nullifier__.unwrap_or_default(),
+                    nullifier: nullifier__,
                 })
             }
         }

proto/penumbra/penumbra/core/component/shielded_pool/v1alpha1/shielded_pool.proto

@@ -6,6 +6,7 @@ import "penumbra/core/keys/v1alpha1/keys.proto";
 import "penumbra/core/num/v1alpha1/num.proto";
 import "penumbra/crypto/decaf377_rdsa/v1alpha1/decaf377_rdsa.proto";
 import "penumbra/crypto/tct/v1alpha1/tct.proto";
+import "penumbra/core/component/sct/v1alpha1/sct.proto";
 
 message Note {
   asset.v1alpha1.Value value = 1;
@@ -64,7 +65,7 @@ message Spend {
 
 // ABCI Event recording a spend.
 message EventSpend {
-  bytes nullifier = 1;
+  core.component.sct.v1alpha1.Nullifier nullifier = 1;
 }
 
 // ABCI Event recording an output.