From 6a6891949b0abedeb9fcfc8e08ef73c969576b60 Mon Sep 17 00:00:00 2001
From: Julien Cretin <cretin@google.com>
Date: Wed, 23 Sep 2020 13:27:20 +0200
Subject: [PATCH] Expose MasterKeys fields again

---
 src/ctap/mod.rs     |  8 ++++----
 src/ctap/storage.rs | 30 +++++++++++++-----------------
 2 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/src/ctap/mod.rs b/src/ctap/mod.rs
index 46f7f07..192067a 100644
--- a/src/ctap/mod.rs
+++ b/src/ctap/mod.rs
@@ -191,7 +191,7 @@ where
         application: &[u8; 32],
     ) -> Result<Vec<u8>, Ctap2StatusCode> {
         let master_keys = self.persistent_store.master_keys()?;
-        let aes_enc_key = crypto::aes256::EncryptionKey::new(master_keys.encryption());
+        let aes_enc_key = crypto::aes256::EncryptionKey::new(&master_keys.encryption);
         let mut sk_bytes = [0; 32];
         private_key.to_bytes(&mut sk_bytes);
         let mut iv = [0; 16];
@@ -209,7 +209,7 @@ where
         for b in &blocks {
             encrypted_id.extend(b);
         }
-        let id_hmac = hmac_256::<Sha256>(master_keys.hmac(), &encrypted_id[..]);
+        let id_hmac = hmac_256::<Sha256>(&master_keys.hmac, &encrypted_id[..]);
         encrypted_id.extend(&id_hmac);
         Ok(encrypted_id)
     }
@@ -228,13 +228,13 @@ where
         let master_keys = self.persistent_store.master_keys()?;
         let payload_size = ENCRYPTED_CREDENTIAL_ID_SIZE - 32;
         if !verify_hmac_256::<Sha256>(
-            master_keys.hmac(),
+            &master_keys.hmac,
             &credential_id[..payload_size],
             array_ref![credential_id, payload_size, 32],
         ) {
             return Ok(None);
         }
-        let aes_enc_key = crypto::aes256::EncryptionKey::new(master_keys.encryption());
+        let aes_enc_key = crypto::aes256::EncryptionKey::new(&master_keys.encryption);
         let aes_dec_key = crypto::aes256::DecryptionKey::new(&aes_enc_key);
         let mut iv = [0; 16];
         iv.copy_from_slice(&credential_id[..16]);
diff --git a/src/ctap/storage.rs b/src/ctap/storage.rs
index 5e8a9ea..de5eb03 100644
--- a/src/ctap/storage.rs
+++ b/src/ctap/storage.rs
@@ -105,16 +105,9 @@ enum Key {
     MinPinLengthRpIds,
 }
 
-pub struct MasterKeys([u8; 64]);
-
-impl MasterKeys {
-    pub fn encryption(&self) -> &[u8; 32] {
-        array_ref!(&self.0, 0, 32)
-    }
-
-    pub fn hmac(&self) -> &[u8; 32] {
-        array_ref!(&self.0, 32, 32)
-    }
+pub struct MasterKeys {
+    pub encryption: [u8; 32],
+    pub hmac: [u8; 32],
 }
 
 struct Config;
@@ -382,7 +375,10 @@ impl PersistentStore {
         if entry.data.len() != 64 {
             return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
         }
-        Ok(MasterKeys(*array_ref![entry.data, 0, 64]))
+        Ok(MasterKeys {
+            encryption: *array_ref![entry.data, 0, 32],
+            hmac: *array_ref![entry.data, 32, 32],
+        })
     }
 
     pub fn pin_hash(&self) -> Result<Option<[u8; PIN_AUTH_LENGTH]>, Ctap2StatusCode> {
@@ -930,17 +926,17 @@ mod test {
         // Master keys stay the same between resets.
         let master_keys_1 = persistent_store.master_keys().unwrap();
         let master_keys_2 = persistent_store.master_keys().unwrap();
-        assert_eq!(master_keys_2.encryption(), master_keys_1.encryption());
-        assert_eq!(master_keys_2.hmac(), master_keys_1.hmac());
+        assert_eq!(master_keys_2.encryption, master_keys_1.encryption);
+        assert_eq!(master_keys_2.hmac, master_keys_1.hmac);
 
         // Master keys change after reset. This test may fail if the random generator produces the
         // same keys.
-        let master_encryption_key = master_keys_1.encryption().to_vec();
-        let master_hmac_key = master_keys_1.hmac().to_vec();
+        let master_encryption_key = master_keys_1.encryption.to_vec();
+        let master_hmac_key = master_keys_1.hmac.to_vec();
         persistent_store.reset(&mut rng).unwrap();
         let master_keys_3 = persistent_store.master_keys().unwrap();
-        assert!(master_keys_3.encryption() != &master_encryption_key[..]);
-        assert!(master_keys_3.hmac() != &master_hmac_key[..]);
+        assert!(master_keys_3.encryption != &master_encryption_key[..]);
+        assert!(master_keys_3.hmac != &master_hmac_key[..]);
     }
 
     #[test]