Use indirection to implement the default KeyStore

src/api/key_store.rs

@@ -50,7 +50,10 @@ pub struct Error;
 /// Key of the environment store reserved for the key store.
 pub const STORE_KEY: usize = 2046;
 
-impl<T: Env> KeyStore for T {
+/// Implements a default key store using the environment rng and store.
+pub trait Helper: Env {}
+
+impl<T: Helper> KeyStore for T {
     fn key_handle_encryption(&mut self) -> Result<[u8; 32], Error> {
         Ok(get_master_keys(self)?.encryption)
     }
@@ -114,8 +117,12 @@ impl From<StoreError> for Error {
     }
 }
 
-#[test]
-fn test_key_store() {
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_key_store() {
         let mut env = crate::env::test::TestEnv::new();
         let key_store = env.key_store();
 
@@ -133,9 +140,10 @@ fn test_key_store() {
         let ecdsa_key = key_store.derive_ecdsa(&ecdsa_seed).unwrap();
         assert_eq!(key_store.derive_ecdsa(&ecdsa_seed), Ok(ecdsa_key));
 
-    // Master keys change after reset. We don't require this for ECDSA seeds because it's not the
-    // case, but it might be better.
+        // Master keys change after reset. We don't require this for ECDSA seeds because it's not
+        // the case, but it might be better.
         key_store.reset().unwrap();
         assert!(key_store.key_handle_encryption().unwrap() != encryption_key);
         assert!(key_store.key_handle_authentication().unwrap() != authentication_key);
+    }
 }

src/env/test/mod.rs

@@ -16,6 +16,7 @@ use self::upgrade_storage::BufferUpgradeStorage;
 use crate::api::connection::{HidConnection, SendOrRecvResult, SendOrRecvStatus};
 use crate::api::customization::DEFAULT_CUSTOMIZATION;
 use crate::api::firmware_protection::FirmwareProtection;
+use crate::api::key_store;
 use crate::api::user_presence::{UserPresence, UserPresenceResult};
 use crate::clock::ClockInt;
 use crate::env::Env;
@@ -147,6 +148,8 @@ impl FirmwareProtection for TestEnv {
     }
 }
 
+impl key_store::Helper for TestEnv {}
+
 impl Env for TestEnv {
     type Rng = TestRng256;
     type UserPresence = TestUserPresence;

src/env/tock/mod.rs

@@ -16,6 +16,7 @@ pub use self::storage::{TockStorage, TockUpgradeStorage};
 use crate::api::connection::{HidConnection, SendOrRecvError, SendOrRecvResult, SendOrRecvStatus};
 use crate::api::customization::{CustomizationImpl, DEFAULT_CUSTOMIZATION};
 use crate::api::firmware_protection::FirmwareProtection;
+use crate::api::key_store;
 use crate::api::user_presence::{UserPresence, UserPresenceError, UserPresenceResult};
 use crate::clock::{ClockInt, KEEPALIVE_DELAY_MS};
 use crate::env::Env;
@@ -193,6 +194,8 @@ impl FirmwareProtection for TockEnv {
     }
 }
 
+impl key_store::Helper for TockEnv {}
+
 impl Env for TockEnv {
     type Rng = TockRng256;
     type UserPresence = Self;