Resolve Android security comments for Android ID migration.

- Use 32 byte key instead of 16 byte.
- Use HMAC-SHA256 instead of SHA256 for ssaid generation.
- Update HMAC with all package signatures.
- Use delimiter in between digest arguments.

This change will cause the ssaid of non-legacy installed apps (apps installed
post Android ID migration OTA) to change after an uninstall and reinstall sequence.

Bug: 34395671
Test: Unit tests, CTS tests, Manual tests
Change-Id: I19dec57947368ee5000c2c630b1e4030d46a4ab3

1 files changed, 2 insertions, 2 deletions

diff --git a/core/java/android/util/ByteStringUtils.java b/core/java/android/util/ByteStringUtils.java
index 7103e6da0625..333208db5f79 100644
--- a/core/java/android/util/ByteStringUtils.java
+++ b/core/java/android/util/ByteStringUtils.java
@@ -33,7 +33,7 @@ public final class ByteStringUtils {
    * @param bytes Byte array to encode.
    * @return Hex encoded string representation of bytes.
    */
-  public static String toString(byte[] bytes) {
+  public static String toHexString(byte[] bytes) {
     if (bytes == null || bytes.length == 0 || bytes.length % 2 != 0) {
       return null;
     }
@@ -55,7 +55,7 @@ public final class ByteStringUtils {
    * @param str Hex encoded string to decode.
    * @return Decoded byte array representation of str.
    */
-  public static byte[] toByteArray(String str) {
+  public static byte[] fromHexToByteArray(String str) {
     if (str == null || str.length() == 0 || str.length() % 2 != 0) {
       return null;
     }