Replace an outdated TODO in Keystore::exportKey
The bug this TODO references has been closed, so replace the TODO with
an explanation of why the code is correct.
Bug: 185811713
Change-Id: I8f4230ab3e290f8ffa8ca25aaa188e8d7156cf8e
diff --git a/Keystore.cpp b/Keystore.cpp
index a017d68..d993b0d 100644
--- a/Keystore.cpp
+++ b/Keystore.cpp
@@ -166,7 +166,13 @@
*key = std::string(ephemeral_key_response.ephemeralKey.begin(),
ephemeral_key_response.ephemeralKey.end());
- // TODO b/185811713 store the upgraded key blob if provided and delete the old key blob.
+ // vold intentionally ignores ephemeral_key_response.upgradedBlob, since the
+ // concept of "upgrading" doesn't make sense for TAG_STORAGE_KEY keys
+ // (hardware-wrapped inline encryption keys). These keys are only meant as
+ // a substitute for raw keys; they still go through vold's usual layer of
+ // key wrapping, which already handles version binding. So, vold just keeps
+ // using the original blobs for TAG_STORAGE_KEY keys. If KeyMint "upgrades"
+ // them anyway, then they'll just get re-upgraded before each use.
ret = true;
out: