| /* |
| * Copyright (C) 2008 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.compat.annotation.UnsupportedAppUsage; |
| import android.os.Parcel; |
| import android.os.Parcelable; |
| |
| import com.android.internal.util.ArrayUtils; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.InputStream; |
| import java.lang.ref.SoftReference; |
| import java.security.PublicKey; |
| import java.security.cert.Certificate; |
| import java.security.cert.CertificateEncodingException; |
| import java.security.cert.CertificateException; |
| import java.security.cert.CertificateFactory; |
| import java.security.cert.X509Certificate; |
| import java.util.Arrays; |
| |
| /** |
| * Opaque, immutable representation of a signing certificate associated with an |
| * application package. |
| * <p> |
| * This class name is slightly misleading, since it's not actually a signature. |
| */ |
| public class Signature implements Parcelable { |
| private final byte[] mSignature; |
| private int mHashCode; |
| private boolean mHaveHashCode; |
| private SoftReference<String> mStringRef; |
| private Certificate[] mCertificateChain; |
| /** |
| * APK Signature Scheme v3 includes support for adding a proof-of-rotation record that |
| * contains two pieces of information: |
| * 1) the past signing certificates |
| * 2) the flags that APK wants to assign to each of the past signing certificates. |
| * |
| * These flags represent the second piece of information and are viewed as capabilities. |
| * They are an APK's way of telling the platform: "this is how I want to trust my old certs, |
| * please enforce that." This is useful for situation where this app itself is using its |
| * signing certificate as an authorization mechanism, like whether or not to allow another |
| * app to have its SIGNATURE permission. An app could specify whether to allow other apps |
| * signed by its old cert 'X' to still get a signature permission it defines, for example. |
| */ |
| private int mFlags; |
| |
| /** |
| * Create Signature from an existing raw byte array. |
| */ |
| public Signature(byte[] signature) { |
| mSignature = signature.clone(); |
| mCertificateChain = null; |
| } |
| |
| /** |
| * Create signature from a certificate chain. Used for backward |
| * compatibility. |
| * |
| * @throws CertificateEncodingException |
| * @hide |
| */ |
| public Signature(Certificate[] certificateChain) throws CertificateEncodingException { |
| mSignature = certificateChain[0].getEncoded(); |
| if (certificateChain.length > 1) { |
| mCertificateChain = Arrays.copyOfRange(certificateChain, 1, certificateChain.length); |
| } |
| } |
| |
| private static final int parseHexDigit(int nibble) { |
| if ('0' <= nibble && nibble <= '9') { |
| return nibble - '0'; |
| } else if ('a' <= nibble && nibble <= 'f') { |
| return nibble - 'a' + 10; |
| } else if ('A' <= nibble && nibble <= 'F') { |
| return nibble - 'A' + 10; |
| } else { |
| throw new IllegalArgumentException("Invalid character " + nibble + " in hex string"); |
| } |
| } |
| |
| /** |
| * Create Signature from a text representation previously returned by |
| * {@link #toChars} or {@link #toCharsString()}. Signatures are expected to |
| * be a hex-encoded ASCII string. |
| * |
| * @param text hex-encoded string representing the signature |
| * @throws IllegalArgumentException when signature is odd-length |
| */ |
| public Signature(String text) { |
| final byte[] input = text.getBytes(); |
| final int N = input.length; |
| |
| if (N % 2 != 0) { |
| throw new IllegalArgumentException("text size " + N + " is not even"); |
| } |
| |
| final byte[] sig = new byte[N / 2]; |
| int sigIndex = 0; |
| |
| for (int i = 0; i < N;) { |
| final int hi = parseHexDigit(input[i++]); |
| final int lo = parseHexDigit(input[i++]); |
| sig[sigIndex++] = (byte) ((hi << 4) | lo); |
| } |
| |
| mSignature = sig; |
| } |
| |
| /** |
| * Sets the flags representing the capabilities of the past signing certificate. |
| * @hide |
| */ |
| public void setFlags(int flags) { |
| this.mFlags = flags; |
| } |
| |
| /** |
| * Returns the flags representing the capabilities of the past signing certificate. |
| * @hide |
| */ |
| public int getFlags() { |
| return mFlags; |
| } |
| |
| /** |
| * Encode the Signature as ASCII text. |
| */ |
| public char[] toChars() { |
| return toChars(null, null); |
| } |
| |
| /** |
| * Encode the Signature as ASCII text in to an existing array. |
| * |
| * @param existingArray Existing char array or null. |
| * @param outLen Output parameter for the number of characters written in |
| * to the array. |
| * @return Returns either <var>existingArray</var> if it was large enough |
| * to hold the ASCII representation, or a newly created char[] array if |
| * needed. |
| */ |
| public char[] toChars(char[] existingArray, int[] outLen) { |
| byte[] sig = mSignature; |
| final int N = sig.length; |
| final int N2 = N*2; |
| char[] text = existingArray == null || N2 > existingArray.length |
| ? new char[N2] : existingArray; |
| for (int j=0; j<N; j++) { |
| byte v = sig[j]; |
| int d = (v>>4)&0xf; |
| text[j*2] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d)); |
| d = v&0xf; |
| text[j*2+1] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d)); |
| } |
| if (outLen != null) outLen[0] = N; |
| return text; |
| } |
| |
| /** |
| * Return the result of {@link #toChars()} as a String. |
| */ |
| public String toCharsString() { |
| String str = mStringRef == null ? null : mStringRef.get(); |
| if (str != null) { |
| return str; |
| } |
| str = new String(toChars()); |
| mStringRef = new SoftReference<String>(str); |
| return str; |
| } |
| |
| /** |
| * @return the contents of this signature as a byte array. |
| */ |
| public byte[] toByteArray() { |
| byte[] bytes = new byte[mSignature.length]; |
| System.arraycopy(mSignature, 0, bytes, 0, mSignature.length); |
| return bytes; |
| } |
| |
| /** |
| * Returns the public key for this signature. |
| * |
| * @throws CertificateException when Signature isn't a valid X.509 |
| * certificate; shouldn't happen. |
| * @hide |
| */ |
| @UnsupportedAppUsage |
| public PublicKey getPublicKey() throws CertificateException { |
| final CertificateFactory certFactory = CertificateFactory.getInstance("X.509"); |
| final ByteArrayInputStream bais = new ByteArrayInputStream(mSignature); |
| final Certificate cert = certFactory.generateCertificate(bais); |
| return cert.getPublicKey(); |
| } |
| |
| /** |
| * Used for compatibility code that needs to check the certificate chain |
| * during upgrades. |
| * |
| * @throws CertificateEncodingException |
| * @hide |
| */ |
| public Signature[] getChainSignatures() throws CertificateEncodingException { |
| if (mCertificateChain == null) { |
| return new Signature[] { this }; |
| } |
| |
| Signature[] chain = new Signature[1 + mCertificateChain.length]; |
| chain[0] = this; |
| |
| int i = 1; |
| for (Certificate c : mCertificateChain) { |
| chain[i++] = new Signature(c.getEncoded()); |
| } |
| |
| return chain; |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| try { |
| if (obj != null) { |
| Signature other = (Signature)obj; |
| return this == other || Arrays.equals(mSignature, other.mSignature); |
| } |
| } catch (ClassCastException e) { |
| } |
| return false; |
| } |
| |
| @Override |
| public int hashCode() { |
| if (mHaveHashCode) { |
| return mHashCode; |
| } |
| mHashCode = Arrays.hashCode(mSignature); |
| mHaveHashCode = true; |
| return mHashCode; |
| } |
| |
| public int describeContents() { |
| return 0; |
| } |
| |
| public void writeToParcel(Parcel dest, int parcelableFlags) { |
| dest.writeByteArray(mSignature); |
| } |
| |
| public static final @android.annotation.NonNull Parcelable.Creator<Signature> CREATOR |
| = new Parcelable.Creator<Signature>() { |
| public Signature createFromParcel(Parcel source) { |
| return new Signature(source); |
| } |
| |
| public Signature[] newArray(int size) { |
| return new Signature[size]; |
| } |
| }; |
| |
| private Signature(Parcel source) { |
| mSignature = source.createByteArray(); |
| } |
| |
| /** |
| * Test if given {@link Signature} sets are exactly equal. |
| * |
| * @hide |
| */ |
| public static boolean areExactMatch(Signature[] a, Signature[] b) { |
| return (a.length == b.length) && ArrayUtils.containsAll(a, b) |
| && ArrayUtils.containsAll(b, a); |
| } |
| |
| /** |
| * Test if given {@link Signature} sets are effectively equal. In rare |
| * cases, certificates can have slightly malformed encoding which causes |
| * exact-byte checks to fail. |
| * <p> |
| * To identify effective equality, we bounce the certificates through an |
| * decode/encode pass before doing the exact-byte check. To reduce attack |
| * surface area, we only allow a byte size delta of a few bytes. |
| * |
| * @throws CertificateException if the before/after length differs |
| * substantially, usually a signal of something fishy going on. |
| * @hide |
| */ |
| public static boolean areEffectiveMatch(Signature[] a, Signature[] b) |
| throws CertificateException { |
| final CertificateFactory cf = CertificateFactory.getInstance("X.509"); |
| |
| final Signature[] aPrime = new Signature[a.length]; |
| for (int i = 0; i < a.length; i++) { |
| aPrime[i] = bounce(cf, a[i]); |
| } |
| final Signature[] bPrime = new Signature[b.length]; |
| for (int i = 0; i < b.length; i++) { |
| bPrime[i] = bounce(cf, b[i]); |
| } |
| |
| return areExactMatch(aPrime, bPrime); |
| } |
| |
| /** |
| * Test if given {@link Signature} objects are effectively equal. In rare |
| * cases, certificates can have slightly malformed encoding which causes |
| * exact-byte checks to fail. |
| * <p> |
| * To identify effective equality, we bounce the certificates through an |
| * decode/encode pass before doing the exact-byte check. To reduce attack |
| * surface area, we only allow a byte size delta of a few bytes. |
| * |
| * @throws CertificateException if the before/after length differs |
| * substantially, usually a signal of something fishy going on. |
| * @hide |
| */ |
| public static boolean areEffectiveMatch(Signature a, Signature b) |
| throws CertificateException { |
| final CertificateFactory cf = CertificateFactory.getInstance("X.509"); |
| |
| final Signature aPrime = bounce(cf, a); |
| final Signature bPrime = bounce(cf, b); |
| |
| return aPrime.equals(bPrime); |
| } |
| |
| /** |
| * Bounce the given {@link Signature} through a decode/encode cycle. |
| * |
| * @throws CertificateException if the before/after length differs |
| * substantially, usually a signal of something fishy going on. |
| * @hide |
| */ |
| public static Signature bounce(CertificateFactory cf, Signature s) throws CertificateException { |
| final InputStream is = new ByteArrayInputStream(s.mSignature); |
| final X509Certificate cert = (X509Certificate) cf.generateCertificate(is); |
| final Signature sPrime = new Signature(cert.getEncoded()); |
| |
| if (Math.abs(sPrime.mSignature.length - s.mSignature.length) > 2) { |
| throw new CertificateException("Bounced cert length looks fishy; before " |
| + s.mSignature.length + ", after " + sPrime.mSignature.length); |
| } |
| |
| return sPrime; |
| } |
| } |