/* Copyright 2019, The Android Open Source Project, Inc. * * 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 com.google.android.attestation; import static com.google.android.attestation.Constants.ATTESTATION_APPLICATION_ID_PACKAGE_INFOS_INDEX; import static com.google.android.attestation.Constants.ATTESTATION_APPLICATION_ID_SIGNATURE_DIGESTS_INDEX; import static com.google.android.attestation.Constants.ATTESTATION_PACKAGE_INFO_PACKAGE_NAME_INDEX; import static com.google.android.attestation.Constants.ATTESTATION_PACKAGE_INFO_VERSION_INDEX; import static java.nio.charset.StandardCharsets.UTF_8; import java.io.IOException; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.Objects; import org.bouncycastle.asn1.ASN1Encodable; import org.bouncycastle.asn1.ASN1Integer; import org.bouncycastle.asn1.ASN1OctetString; import org.bouncycastle.asn1.ASN1Sequence; import org.bouncycastle.asn1.ASN1Set; import org.bouncycastle.asn1.DEROctetString; /** * This data structure reflects the Android platform's belief as to which apps are allowed to use * the secret key material under attestation. The ID can comprise multiple packages if and only if * multiple packages share the same UID. */ public class AttestationApplicationId implements Comparable<AttestationApplicationId> { public final List<AttestationPackageInfo> packageInfos; public final List<byte[]> signatureDigests; private AttestationApplicationId(DEROctetString attestationApplicationId) throws IOException { ASN1Sequence attestationApplicationIdSequence = (ASN1Sequence) ASN1Sequence.fromByteArray(attestationApplicationId.getOctets()); ASN1Set attestationPackageInfos = (ASN1Set) attestationApplicationIdSequence.getObjectAt( ATTESTATION_APPLICATION_ID_PACKAGE_INFOS_INDEX); this.packageInfos = new ArrayList<>(); for (ASN1Encodable packageInfo : attestationPackageInfos) { this.packageInfos.add(new AttestationPackageInfo((ASN1Sequence) packageInfo)); } ASN1Set digests = (ASN1Set) attestationApplicationIdSequence.getObjectAt( ATTESTATION_APPLICATION_ID_SIGNATURE_DIGESTS_INDEX); this.signatureDigests = new ArrayList<>(); for (ASN1Encodable digest : digests) { this.signatureDigests.add(((ASN1OctetString) digest).getOctets()); } } AttestationApplicationId( List<AttestationPackageInfo> packageInfos, List<byte[]> signatureDigests) { this.packageInfos = packageInfos; this.signatureDigests = signatureDigests; } static AttestationApplicationId createAttestationApplicationId( DEROctetString attestationApplicationId) { if (attestationApplicationId == null) { return null; } try { return new AttestationApplicationId(attestationApplicationId); } catch (IOException e) { return null; } } @Override public int compareTo(AttestationApplicationId other) { int res = Integer.compare(packageInfos.size(), other.packageInfos.size()); if (res != 0) { return res; } for (int i = 0; i < packageInfos.size(); ++i) { res = packageInfos.get(i).compareTo(other.packageInfos.get(i)); if (res != 0) { return res; } } res = Integer.compare(signatureDigests.size(), other.signatureDigests.size()); if (res != 0) { return res; } ByteArrayComparator cmp = new ByteArrayComparator(); for (int i = 0; i < signatureDigests.size(); ++i) { res = cmp.compare(signatureDigests.get(i), other.signatureDigests.get(i)); if (res != 0) { return res; } } return res; } @Override public boolean equals(Object o) { return (o instanceof AttestationApplicationId) && (compareTo((AttestationApplicationId) o) == 0); } @Override public int hashCode() { return Objects.hash(packageInfos, Arrays.deepHashCode(signatureDigests.toArray())); } /** Provides package's name and version number. */ public static class AttestationPackageInfo implements Comparable<AttestationPackageInfo> { public final String packageName; public final long version; private AttestationPackageInfo(ASN1Sequence packageInfo) { this.packageName = new String( ((ASN1OctetString) packageInfo.getObjectAt(ATTESTATION_PACKAGE_INFO_PACKAGE_NAME_INDEX)) .getOctets(), UTF_8); this.version = ((ASN1Integer) packageInfo.getObjectAt(ATTESTATION_PACKAGE_INFO_VERSION_INDEX)) .getValue() .longValue(); } AttestationPackageInfo(String packageName, long version) { this.packageName = packageName; this.version = version; } @Override public int compareTo(AttestationPackageInfo other) { int res = packageName.compareTo(other.packageName); if (res != 0) { return res; } res = Long.compare(version, other.version); if (res != 0) { return res; } return res; } @Override public boolean equals(Object o) { return (o instanceof AttestationPackageInfo) && (compareTo((AttestationPackageInfo) o) == 0); } @Override public int hashCode() { return Objects.hash(packageName, version); } } private static class ByteArrayComparator implements java.util.Comparator<byte[]> { @Override public int compare(byte[] a, byte[] b) { int res = Integer.compare(a.length, b.length); if (res != 0) { return res; } for (int i = 0; i < a.length; ++i) { res = Byte.compare(a[i], b[i]); if (res != 0) { return res; } } return res; } } }