commit e35797ffcae45788f80e0705ef8187a9b1ce74d1
author David Zeuthen <zeuthen@google.com> Thu Feb 27 14:25:54 2020 -0500
committer David Zeuthen <zeuthen@google.com> Thu Feb 27 14:31:57 2020 -0500
tree 40fcf839c1034082cda394d93abb6dd85d1612d2
parent d7975bf8d57434e06d2dba62a06436e53d8207cc

Identity: Move signingKeyBlob from finishRetrieval() to startRetrieval().

The implementation of the Identity Credential TA in constrained
environments may need to incrementally update the HMAC-SHA256 of
DeviceAuthencation CBOR to avoid keeping the entire CBOR structure in
memory. To do this they need to calculate the derived key before
starting to build the CBOR so they need access to the signingKey
earlier on.

Bug: 150390415
Test: atest android.security.identity.cts
Test: VtsHalIdentityTargetTest
Change-Id: I72ad30ec3ccec0b8161cbea360ef8c9212f8cbbc

identity/aidl/vts/VtsHalIdentityTargetTest.cpp

diff --git a/identity/aidl/vts/VtsHalIdentityTargetTest.cpp b/identity/aidl/vts/VtsHalIdentityTargetTest.cpp
index 5abe5a2..ea37fdc 100644
--- a/identity/aidl/vts/VtsHalIdentityTargetTest.cpp
+++ b/identity/aidl/vts/VtsHalIdentityTargetTest.cpp
@@ -352,10 +352,15 @@
                                    readerCertificate.value());
     ASSERT_TRUE(readerSignature);
 
+    // Generate the key that will be used to sign AuthenticatedData.
+    vector<uint8_t> signingKeyBlob;
+    Certificate signingKeyCertificate;
+    ASSERT_TRUE(credential->generateSigningKeyPair(&signingKeyBlob, &signingKeyCertificate).isOk());
+
     ASSERT_TRUE(credential
                         ->startRetrieval(returnedSecureProfiles, authToken, itemsRequestBytes,
-                                         sessionTranscriptBytes, readerSignature.value(),
-                                         testEntriesEntryCounts)
+                                         signingKeyBlob, sessionTranscriptBytes,
+                                         readerSignature.value(), testEntriesEntryCounts)
                         .isOk());
 
     for (const auto& entry : testEntries) {
@@ -377,14 +382,9 @@
         EXPECT_EQ(content, entry.valueCbor);
     }
 
-    // Generate the key that will be used to sign AuthenticatedData.
-    vector<uint8_t> signingKeyBlob;
-    Certificate signingKeyCertificate;
-    ASSERT_TRUE(credential->generateSigningKeyPair(&signingKeyBlob, &signingKeyCertificate).isOk());
-
     vector<uint8_t> mac;
     vector<uint8_t> deviceNameSpacesBytes;
-    ASSERT_TRUE(credential->finishRetrieval(signingKeyBlob, &mac, &deviceNameSpacesBytes).isOk());
+    ASSERT_TRUE(credential->finishRetrieval(&mac, &deviceNameSpacesBytes).isOk());
     cborPretty = support::cborPrettyPrint(deviceNameSpacesBytes, 32, {});
     ASSERT_EQ(
             "{\n"