Implement a newtype for Precision

crates/core/app/Cargo.toml

@@ -81,6 +81,7 @@ tracing                          = { workspace = true }
 url                              = { workspace = true }
 
 [dev-dependencies]
+decaf377-fmd            = { workspace = true, default-features = true }
 ed25519-consensus       = { workspace = true }
 penumbra-mock-consensus = { workspace = true }
 penumbra-mock-client    = { workspace = true }

crates/core/app/src/action_handler/transaction.rs

@@ -166,7 +166,11 @@ mod tests {
                 OutputPlan::new(&mut OsRng, value, *test_keys::ADDRESS_1).into(),
             ],
             detection_data: Some(DetectionDataPlan {
-                clue_plans: vec![CluePlan::new(&mut OsRng, *test_keys::ADDRESS_1, 1)],
+                clue_plans: vec![CluePlan::new(
+                    &mut OsRng,
+                    *test_keys::ADDRESS_1,
+                    1.try_into().unwrap(),
+                )],
             }),
             memo: None,
         };

crates/core/app/src/action_handler/transaction/stateful.rs

@@ -31,8 +31,8 @@ pub async fn fmd_parameters_valid<S: StateRead>(state: S, transaction: &Transact
 #[tracing::instrument(
     skip_all,
     fields(
-        current_fmd.precision_bits = current_fmd_parameters.precision_bits,
-        previous_fmd.precision_bits = previous_fmd_parameters.precision_bits,
+        current_fmd.precision_bits = current_fmd_parameters.precision.bits(),
+        previous_fmd.precision_bits = previous_fmd_parameters.precision.bits(),
         previous_fmd.as_of_block_height = previous_fmd_parameters.as_of_block_height,
         block_height,
     )
@@ -51,9 +51,9 @@ pub fn fmd_precision_within_grace_period(
     {
         // Clue must be using the current `fmd::Parameters`, or be within
         // `FMD_GRACE_PERIOD_BLOCKS` of the previous `fmd::Parameters`.
-        let clue_precision = clue.precision_bits();
-        let using_current_precision = clue_precision == current_fmd_parameters.precision_bits;
-        let using_previous_precision = clue_precision == previous_fmd_parameters.precision_bits;
+        let clue_precision = clue.precision()?;
+        let using_current_precision = clue_precision == current_fmd_parameters.precision;
+        let using_previous_precision = clue_precision == previous_fmd_parameters.precision;
         let within_grace_period =
             block_height < previous_fmd_parameters.as_of_block_height + FMD_GRACE_PERIOD_BLOCKS;
         if using_current_precision || (using_previous_precision && within_grace_period) {

crates/core/app/tests/app_can_define_and_delegate_to_a_validator.rs

@@ -1,3 +1,5 @@
+use decaf377_fmd::Precision;
+
 mod common;
 
 use {
@@ -164,7 +166,7 @@ async fn app_can_define_and_delegate_to_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;
@@ -275,7 +277,7 @@ async fn app_can_define_and_delegate_to_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;
@@ -440,7 +442,7 @@ async fn app_can_define_and_delegate_to_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;

crates/core/app/tests/app_can_spend_notes_and_detect_outputs.rs

@@ -1,3 +1,5 @@
+use decaf377_fmd::Precision;
+
 mod common;
 
 use {
@@ -65,7 +67,7 @@ async fn app_can_spend_notes_and_detect_outputs() -> anyhow::Result<()> {
             ..Default::default()
         },
     };
-    plan.populate_detection_data(OsRng, 0);
+    plan.populate_detection_data(OsRng, Precision::default());
 
     let tx = client.witness_auth_build(&plan).await?;
 

crates/core/app/tests/app_can_undelegate_from_a_validator.rs

@@ -1,3 +1,4 @@
+use decaf377_fmd::Precision;
 use penumbra_num::fixpoint::U128x128;
 
 mod common;
@@ -160,7 +161,7 @@ async fn app_can_undelegate_from_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         (plan, note, staking_note_nullifier)
     };
     let tx = client.witness_auth_build(&plan).await?;
@@ -263,7 +264,7 @@ async fn app_can_undelegate_from_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         (plan, undelegate_token_id)
     };
     let tx = client.witness_auth_build(&plan).await?;
@@ -345,7 +346,7 @@ async fn app_can_undelegate_from_a_validator() -> anyhow::Result<()> {
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;

crates/core/app/tests/app_tracks_uptime_for_validators_only_once_active.rs

@@ -1,3 +1,5 @@
+use decaf377_fmd::Precision;
+
 mod common;
 
 use {
@@ -139,7 +141,7 @@ async fn app_tracks_uptime_for_validators_only_once_active() -> anyhow::Result<(
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
 
@@ -214,7 +216,7 @@ async fn app_tracks_uptime_for_validators_only_once_active() -> anyhow::Result<(
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;
@@ -345,7 +347,7 @@ async fn app_tracks_uptime_for_validators_only_once_active() -> anyhow::Result<(
                 ..Default::default()
             },
         };
-        plan.populate_detection_data(rand_core::OsRng, 0);
+        plan.populate_detection_data(rand_core::OsRng, Precision::default());
         plan
     };
     let tx = client.witness_auth_build(&plan).await?;

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

@@ -1,3 +1,4 @@
+use decaf377_fmd::Precision;
 use penumbra_proto::{core::component::shielded_pool::v1 as pb, DomainType};
 use serde::{Deserialize, Serialize};
 
@@ -6,8 +7,8 @@ pub mod state_key;
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(try_from = "pb::FmdParameters", into = "pb::FmdParameters")]
 pub struct Parameters {
-    /// Bits of precision.
-    pub precision_bits: u8,
+    /// FMD Precision.
+    pub precision: Precision,
     /// The block height at which these parameters became effective.
     pub as_of_block_height: u64,
 }
@@ -21,7 +22,7 @@ impl TryFrom<pb::FmdParameters> for Parameters {
 
     fn try_from(msg: pb::FmdParameters) -> Result<Self, Self::Error> {
         Ok(Parameters {
-            precision_bits: msg.precision_bits.try_into()?,
+            precision: msg.precision_bits.try_into()?,
             as_of_block_height: msg.as_of_block_height,
         })
     }
@@ -30,7 +31,7 @@ impl TryFrom<pb::FmdParameters> for Parameters {
 impl From<Parameters> for pb::FmdParameters {
     fn from(params: Parameters) -> Self {
         pb::FmdParameters {
-            precision_bits: u32::from(params.precision_bits),
+            precision_bits: params.precision.bits() as u32,
             as_of_block_height: params.as_of_block_height,
         }
     }
@@ -39,7 +40,7 @@ impl From<Parameters> for pb::FmdParameters {
 impl Default for Parameters {
     fn default() -> Self {
         Self {
-            precision_bits: 0,
+            precision: Precision::default(),
             as_of_block_height: 1,
         }
     }

crates/core/transaction/src/plan.rs

@@ -2,6 +2,7 @@
 //! creation.
 
 use anyhow::Result;
+use decaf377_fmd::Precision;
 use penumbra_community_pool::{CommunityPoolDeposit, CommunityPoolOutput, CommunityPoolSpend};
 use penumbra_dex::{
     lp::action::{PositionClose, PositionOpen},
@@ -351,19 +352,19 @@ impl TransactionPlan {
     pub fn populate_detection_data<R: CryptoRng + Rng>(
         &mut self,
         mut rng: R,
-        precision_bits: usize,
+        precision: Precision,
     ) {
         // Add one clue per recipient.
         let mut clue_plans = vec![];
         for dest_address in self.dest_addresses() {
-            clue_plans.push(CluePlan::new(&mut rng, dest_address, precision_bits));
+            clue_plans.push(CluePlan::new(&mut rng, dest_address, precision));
         }
 
         // Now add dummy clues until we have one clue per output.
         let num_dummy_clues = self.num_outputs() - clue_plans.len();
         for _ in 0..num_dummy_clues {
             let dummy_address = Address::dummy(&mut rng);
-            clue_plans.push(CluePlan::new(&mut rng, dummy_address, precision_bits));
+            clue_plans.push(CluePlan::new(&mut rng, dummy_address, precision));
         }
 
         if !clue_plans.is_empty() {
@@ -521,7 +522,7 @@ mod tests {
                 chain_id: "penumbra-test".to_string(),
             },
             detection_data: Some(DetectionDataPlan {
-                clue_plans: vec![CluePlan::new(&mut OsRng, addr, 1)],
+                clue_plans: vec![CluePlan::new(&mut OsRng, addr, 1.try_into().unwrap())],
             }),
             memo: Some(MemoPlan::new(&mut OsRng, memo_plaintext.clone()).unwrap()),
         };

crates/core/transaction/src/plan/clue.rs

@@ -1,4 +1,4 @@
-use decaf377_fmd::Clue;
+use decaf377_fmd::{Clue, Precision};
 use penumbra_keys::Address;
 use penumbra_proto::{core::transaction::v1 as pb, DomainType};
 
@@ -7,7 +7,7 @@ use rand::{CryptoRng, RngCore};
 #[derive(Clone, Debug)]
 pub struct CluePlan {
     pub address: Address,
-    pub precision_bits: usize,
+    pub precision: Precision,
     pub rseed: [u8; 32],
 }
 
@@ -16,14 +16,14 @@ impl CluePlan {
     pub fn new<R: CryptoRng + RngCore>(
         rng: &mut R,
         address: Address,
-        precision_bits: usize,
+        precision: Precision,
     ) -> CluePlan {
         let mut rseed = [0u8; 32];
         rng.fill_bytes(&mut rseed);
         CluePlan {
             address,
             rseed,
-            precision_bits,
+            precision,
         }
     }
 
@@ -32,7 +32,7 @@ impl CluePlan {
         let clue_key = self.address.clue_key();
         let expanded_clue_key = clue_key.expand_infallible();
         expanded_clue_key
-            .create_clue_deterministic(self.precision_bits, self.rseed)
+            .create_clue_deterministic(self.precision, self.rseed)
             .expect("can construct clue key")
     }
 }
@@ -46,7 +46,7 @@ impl From<CluePlan> for pb::CluePlan {
         Self {
             address: Some(msg.address.into()),
             rseed: msg.rseed.to_vec(),
-            precision_bits: msg.precision_bits as u64,
+            precision_bits: msg.precision.bits() as u64,
         }
     }
 }
@@ -60,7 +60,7 @@ impl TryFrom<pb::CluePlan> for CluePlan {
                 .ok_or_else(|| anyhow::anyhow!("missing address"))?
                 .try_into()?,
             rseed: msg.rseed.as_slice().try_into()?,
-            precision_bits: msg.precision_bits.try_into()?,
+            precision: msg.precision_bits.try_into()?,
         })
     }
 }

crates/crypto/decaf377-fmd/benches/fmd.rs

@@ -1,4 +1,5 @@
 use criterion::{criterion_group, criterion_main, Criterion, Throughput};
+use fmd::Precision;
 use rand_core::OsRng;
 
 use decaf377_fmd as fmd;
@@ -7,7 +8,7 @@ fn detect_clues(dk: &fmd::DetectionKey, clues: &[fmd::Clue]) -> usize {
     clues.iter().filter(|clue| dk.examine(clue)).count()
 }
 
-fn create_clues(ck: &fmd::ExpandedClueKey, precision: usize) -> Vec<fmd::Clue> {
+fn create_clues(ck: &fmd::ExpandedClueKey, precision: Precision) -> Vec<fmd::Clue> {
     (0..1024)
         .map(|_| {
             ck.create_clue(precision, OsRng)
@@ -24,11 +25,11 @@ fn bench(c: &mut Criterion) {
         .expect("clue key bytes must be valid");
 
     let clues = vec![
-        (4, create_clues(&ck, 4)),
-        (5, create_clues(&ck, 5)),
-        (6, create_clues(&ck, 6)),
-        (7, create_clues(&ck, 7)),
-        (8, create_clues(&ck, 8)),
+        (4, create_clues(&ck, 4.try_into().unwrap())),
+        (5, create_clues(&ck, 5.try_into().unwrap())),
+        (6, create_clues(&ck, 6.try_into().unwrap())),
+        (7, create_clues(&ck, 7.try_into().unwrap())),
+        (8, create_clues(&ck, 8.try_into().unwrap())),
     ];
 
     let mut group = c.benchmark_group("fmd-detection");

crates/crypto/decaf377-fmd/src/clue.rs

@@ -1,10 +1,28 @@
+use std::array::TryFromSliceError;
+
+use crate::{error::Error, Precision};
+
 /// A clue that allows probabilistic message detection.
 #[derive(Debug, Clone)]
-pub struct Clue(pub [u8; 68]);
+pub struct Clue(pub(crate) [u8; 68]);
 
 impl Clue {
-    /// The bits of precision for this `Clue`.
-    pub fn precision_bits(&self) -> u8 {
-        self.0[64]
+    /// The bits of precision for this `Clue`, if valid.
+    pub fn precision(&self) -> Result<Precision, Error> {
+        self.0[64].try_into()
+    }
+}
+
+impl From<Clue> for Vec<u8> {
+    fn from(value: Clue) -> Self {
+        value.0.into()
+    }
+}
+
+impl TryFrom<&[u8]> for Clue {
+    type Error = TryFromSliceError;
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        Ok(Self(value.try_into()?))
     }
 }