WifiConfigStoreEncryptionUtil: Use 256 bit secret key

Bug: 140485110
Test: Manual verification
- Store a PSK network config on older build
- Upgrade to build with this CL
- adb shell settings put global niap_mode 1
- Ensured that the psk was read correctly on upgrade
- Ensured that the psk was encrypted when stored on disk after upgrade

Change-Id: I3b98c2c83b8aa6280c793068e5c275543ba69e8b

1 files changed, 2 insertions, 0 deletions

diff --git a/service/java/com/android/server/wifi/util/WifiConfigStoreEncryptionUtil.java b/service/java/com/android/server/wifi/util/WifiConfigStoreEncryptionUtil.java
index 2f9b08f2b..46bf0fee1 100644
--- a/service/java/com/android/server/wifi/util/WifiConfigStoreEncryptionUtil.java
+++ b/service/java/com/android/server/wifi/util/WifiConfigStoreEncryptionUtil.java
@@ -51,6 +51,7 @@ public class WifiConfigStoreEncryptionUtil {
     private static final String ALIAS_SUFFIX = ".data-encryption-key";
     private static final String CIPHER_ALGORITHM = "AES/GCM/NoPadding";
     private static final int GCM_TAG_LENGTH = 128;
+    private static final int KEY_LENGTH = 256;
     private static final String KEY_STORE = "AndroidKeyStore";
 
     private final String mDataFileName;
@@ -160,6 +161,7 @@ public class WifiConfigStoreEncryptionUtil {
                         KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
                         .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
                         .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
+                        .setKeySize(KEY_LENGTH)
                         .setUid(Process.WIFI_UID)
                         .build();