Add SigningInfo class to expose package signing details.
Attempt to simplify the exposure of package signing information via
PackageInfo by creating a new class and corresponding methods for
querying a package's signing information.
Bug: 74831530
Test: PkgInstallSignatureVerificationTest
Change-Id: Idbc008b41a921f89cefb224b26f910da4d238dea
diff --git a/core/java/android/content/pm/SigningInfo.java b/core/java/android/content/pm/SigningInfo.java
new file mode 100644
index 0000000..ef87403
--- /dev/null
+++ b/core/java/android/content/pm/SigningInfo.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.content.pm;
+
+
+import android.annotation.NonNull;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+/**
+ * Information pertaining to the signing certificates used to sign a package.
+ */
+public final class SigningInfo implements Parcelable {
+
+ @NonNull
+ private final PackageParser.SigningDetails mSigningDetails;
+
+ public SigningInfo() {
+ mSigningDetails = PackageParser.SigningDetails.UNKNOWN;
+ }
+
+ /**
+ * @hide only packagemanager should be populating this
+ */
+ public SigningInfo(PackageParser.SigningDetails signingDetails) {
+ mSigningDetails = new PackageParser.SigningDetails(signingDetails);
+ }
+
+ public SigningInfo(SigningInfo orig) {
+ mSigningDetails = new PackageParser.SigningDetails(orig.mSigningDetails);
+ }
+
+ private SigningInfo(Parcel source) {
+ mSigningDetails = PackageParser.SigningDetails.CREATOR.createFromParcel(source);
+ }
+
+ /**
+ * Although relatively uncommon, packages may be signed by more than one signer, in which case
+ * their identity is viewed as being the set of all signers, not just any one.
+ */
+ public boolean hasMultipleSigners() {
+ return mSigningDetails.signatures != null && mSigningDetails.signatures.length > 1;
+ }
+
+ /**
+ * APK Signature Scheme v3 enables packages to provide a proof-of-rotation record that the
+ * platform verifies, and uses, to allow the use of new signing certificates. This is only
+ * available to packages that are not signed by multiple signers. In the event of a change to a
+ * new signing certificate, the package's past signing certificates are presented as well. Any
+ * check of a package's signing certificate should also include a search through its entire
+ * signing history, since it could change to a new signing certificate at any time.
+ */
+ public boolean hasPastSigningCertificates() {
+ return mSigningDetails.signatures != null
+ && mSigningDetails.pastSigningCertificates != null;
+ }
+
+ /**
+ * Returns the signing certificates this package has proven it is authorized to use. This
+ * includes both the signing certificate associated with the signer of the package and the past
+ * signing certificates it included as its proof of signing certificate rotation. This method
+ * is the preferred replacement for the {@code GET_SIGNATURES} flag used with {@link
+ * PackageManager#getPackageInfo(String, int)}. When determining if a package is signed by a
+ * desired certificate, the returned array should be checked to determine if it is one of the
+ * entries.
+ *
+ * <note>
+ * This method returns null if the package is signed by multiple signing certificates, as
+ * opposed to being signed by one current signer and also providing the history of past
+ * signing certificates. {@link #hasMultipleSigners()} may be used to determine if this
+ * package is signed by multiple signers. Packages which are signed by multiple signers
+ * cannot change their signing certificates and their {@code Signature} array should be
+ * checked to make sure that every entry matches the looked-for signing certificates.
+ * </note>
+ */
+ public Signature[] getSigningCertificateHistory() {
+ if (hasMultipleSigners()) {
+ return null;
+ } else if (!hasPastSigningCertificates()) {
+
+ // this package is only signed by one signer with no history, return it
+ return mSigningDetails.signatures;
+ } else {
+
+ // this package has provided proof of past signing certificates, include them
+ return mSigningDetails.pastSigningCertificates;
+ }
+ }
+
+ /**
+ * Returns the signing certificates used to sign the APK contents of this application. Not
+ * including any past signing certificates the package proved it is authorized to use.
+ * <note>
+ * This method should not be used unless {@link #hasMultipleSigners()} returns true,
+ * indicating that {@link #getSigningCertificateHistory()} cannot be used, otherwise {@link
+ * #getSigningCertificateHistory()} should be preferred.
+ * </note>
+ */
+ public Signature[] getApkContentsSigners() {
+ return mSigningDetails.signatures;
+ }
+
+ @Override
+ public int describeContents() {
+ return 0;
+ }
+
+ @Override
+ public void writeToParcel(Parcel dest, int parcelableFlags) {
+ mSigningDetails.writeToParcel(dest, parcelableFlags);
+ }
+
+ public static final Parcelable.Creator<SigningInfo> CREATOR =
+ new Parcelable.Creator<SigningInfo>() {
+ @Override
+ public SigningInfo createFromParcel(Parcel source) {
+ return new SigningInfo(source);
+ }
+
+ @Override
+ public SigningInfo[] newArray(int size) {
+ return new SigningInfo[size];
+ }
+ };
+}