Document the allowed challenge size
KeyMint should be able to handle challenges up to 128 bytes.
Document this (and the expected error code) in Tag.aidl.
Bug: 307714384
Test: m
Change-Id: Id099dd055c81b10d777effdf364395f84d8b35c6
diff --git a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
index 36f0106..aa7bf28 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
@@ -643,6 +643,8 @@
* Tag::ATTESTATION_CHALLENGE is used to deliver a "challenge" value to the attested key
* generation/import methods, which must place the value in the KeyDescription SEQUENCE of the
* attestation extension.
+ * The challenge value may be up to 128 bytes. If the caller provides a bigger challenge,
+ * INVALID_INPUT_LENGTH error should be returned.
*
* Must never appear in KeyCharacteristics.
*/