Support blake2b-256 in hashtree builder

Now that blake2b-256 can be used to generate hashtree, add
the algorithm support in hashtree builder. This is needed to
perform on-device verity computation during an OTA update.

Bug: 178117377
Test: disable vabc on CF, check blake2b-256 verity tree generates correctly on device
Change-Id: I54de6f9db34f7b128f914de15af9b7fb61c41d1a

2 files changed, 15 insertions, 0 deletions

diff --git a/verity/build_verity_tree_test.cpp b/verity/build_verity_tree_test.cpp
index 8e1f114a..74fe9c06 100644
--- a/verity/build_verity_tree_test.cpp
+++ b/verity/build_verity_tree_test.cpp
@@ -101,6 +101,18 @@ TEST_F(BuildVerityTreeTest, HashSingleLevel) {
             HashTreeBuilder::BytesArrayToString(builder->root_hash()));
 }
 
+TEST_F(BuildVerityTreeTest, HashSingleLevel_blake2b256) {
+  std::vector<unsigned char> data(128 * 4096, 0x0);
+
+  builder.reset(
+      new HashTreeBuilder(4096, HashTreeBuilder::HashFunction("blake2b-256")));
+
+  GenerateHashTree(data, salt_hex);
+  ASSERT_EQ(1u, verity_tree().size());
+  ASSERT_EQ("6d5b006af5308523f7db6956c60b2650ff3e7edab1e2194cc8ee19b1a1398c03",
+            HashTreeBuilder::BytesArrayToString(builder->root_hash()));
+}
+
 TEST_F(BuildVerityTreeTest, HashMultipleLevels) {
   std::vector<unsigned char> data(129 * 4096, 0xff);
 
diff --git a/verity/hash_tree_builder.cpp b/verity/hash_tree_builder.cpp
index df6f7864..52899a35 100644
--- a/verity/hash_tree_builder.cpp
+++ b/verity/hash_tree_builder.cpp
@@ -42,6 +42,9 @@ const EVP_MD* HashTreeBuilder::HashFunction(const std::string& hash_name) {
   if (android::base::EqualsIgnoreCase(hash_name, "sha512")) {
     return EVP_sha512();
   }
+  if (android::base::EqualsIgnoreCase(hash_name, "blake2b-256")) {
+    return EVP_blake2b256();
+  }
 
   LOG(ERROR) << "Unsupported hash algorithm " << hash_name;
   return nullptr;