309 lines
11 KiB
Java
309 lines
11 KiB
Java
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/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.verity;
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import java.io.ByteArrayInputStream;
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import java.io.IOException;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.Security;
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import java.security.cert.X509Certificate;
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import java.security.cert.Certificate;
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import java.security.cert.CertificateFactory;
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import java.security.cert.CertificateEncodingException;
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import java.util.Arrays;
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import org.bouncycastle.asn1.ASN1Encodable;
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import org.bouncycastle.asn1.ASN1EncodableVector;
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import org.bouncycastle.asn1.ASN1Integer;
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import org.bouncycastle.asn1.ASN1Object;
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import org.bouncycastle.asn1.ASN1ObjectIdentifier;
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import org.bouncycastle.asn1.ASN1OctetString;
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import org.bouncycastle.asn1.ASN1Primitive;
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import org.bouncycastle.asn1.ASN1Sequence;
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import org.bouncycastle.asn1.ASN1InputStream;
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import org.bouncycastle.asn1.DEROctetString;
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import org.bouncycastle.asn1.DERPrintableString;
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import org.bouncycastle.asn1.DERSequence;
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import org.bouncycastle.asn1.util.ASN1Dump;
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import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
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import org.bouncycastle.jce.provider.BouncyCastleProvider;
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/**
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* AndroidVerifiedBootSignature DEFINITIONS ::=
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* BEGIN
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* formatVersion ::= INTEGER
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* certificate ::= Certificate
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* algorithmIdentifier ::= SEQUENCE {
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* algorithm OBJECT IDENTIFIER,
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* parameters ANY DEFINED BY algorithm OPTIONAL
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* }
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* authenticatedAttributes ::= SEQUENCE {
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* target CHARACTER STRING,
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* length INTEGER
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* }
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* signature ::= OCTET STRING
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* END
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*/
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public class BootSignature extends ASN1Object
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{
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private ASN1Integer formatVersion;
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private ASN1Encodable certificate;
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private AlgorithmIdentifier algorithmIdentifier;
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private DERPrintableString target;
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private ASN1Integer length;
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private DEROctetString signature;
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private PublicKey publicKey;
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private static final int FORMAT_VERSION = 1;
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/**
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* Initializes the object for signing an image file
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* @param target Target name, included in the signed data
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* @param length Length of the image, included in the signed data
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*/
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public BootSignature(String target, int length) {
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this.formatVersion = new ASN1Integer(FORMAT_VERSION);
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this.target = new DERPrintableString(target);
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this.length = new ASN1Integer(length);
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}
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/**
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* Initializes the object for verifying a signed image file
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* @param signature Signature footer
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*/
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public BootSignature(byte[] signature)
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throws Exception {
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ASN1InputStream stream = new ASN1InputStream(signature);
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ASN1Sequence sequence = (ASN1Sequence) stream.readObject();
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formatVersion = (ASN1Integer) sequence.getObjectAt(0);
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if (formatVersion.getValue().intValue() != FORMAT_VERSION) {
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throw new IllegalArgumentException("Unsupported format version");
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}
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certificate = sequence.getObjectAt(1);
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byte[] encoded = ((ASN1Object) certificate).getEncoded();
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ByteArrayInputStream bis = new ByteArrayInputStream(encoded);
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CertificateFactory cf = CertificateFactory.getInstance("X.509");
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X509Certificate c = (X509Certificate) cf.generateCertificate(bis);
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publicKey = c.getPublicKey();
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ASN1Sequence algId = (ASN1Sequence) sequence.getObjectAt(2);
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algorithmIdentifier = new AlgorithmIdentifier(
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(ASN1ObjectIdentifier) algId.getObjectAt(0));
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ASN1Sequence attrs = (ASN1Sequence) sequence.getObjectAt(3);
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target = (DERPrintableString) attrs.getObjectAt(0);
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length = (ASN1Integer) attrs.getObjectAt(1);
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this.signature = (DEROctetString) sequence.getObjectAt(4);
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}
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public ASN1Object getAuthenticatedAttributes() {
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ASN1EncodableVector attrs = new ASN1EncodableVector();
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attrs.add(target);
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attrs.add(length);
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return new DERSequence(attrs);
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}
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public byte[] getEncodedAuthenticatedAttributes() throws IOException {
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return getAuthenticatedAttributes().getEncoded();
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}
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public AlgorithmIdentifier getAlgorithmIdentifier() {
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return algorithmIdentifier;
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}
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public PublicKey getPublicKey() {
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return publicKey;
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}
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public byte[] getSignature() {
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return signature.getOctets();
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}
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public void setSignature(byte[] sig, AlgorithmIdentifier algId) {
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algorithmIdentifier = algId;
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signature = new DEROctetString(sig);
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}
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public void setCertificate(X509Certificate cert)
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throws Exception, IOException, CertificateEncodingException {
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ASN1InputStream s = new ASN1InputStream(cert.getEncoded());
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certificate = s.readObject();
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}
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public byte[] generateSignableImage(byte[] image) throws IOException {
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byte[] attrs = getEncodedAuthenticatedAttributes();
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byte[] signable = Arrays.copyOf(image, image.length + attrs.length);
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for (int i=0; i < attrs.length; i++) {
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signable[i+image.length] = attrs[i];
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}
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return signable;
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}
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public byte[] sign(byte[] image, PrivateKey key) throws Exception {
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byte[] signable = generateSignableImage(image);
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return Utils.sign(key, signable);
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}
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public boolean verify(byte[] image) throws Exception {
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if (length.getValue().intValue() != image.length) {
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throw new IllegalArgumentException("Invalid image length");
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}
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byte[] signable = generateSignableImage(image);
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return Utils.verify(publicKey, signable, signature.getOctets(),
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algorithmIdentifier);
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}
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public ASN1Primitive toASN1Primitive() {
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ASN1EncodableVector v = new ASN1EncodableVector();
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v.add(formatVersion);
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v.add(certificate);
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v.add(algorithmIdentifier);
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v.add(getAuthenticatedAttributes());
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v.add(signature);
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return new DERSequence(v);
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}
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public static int getSignableImageSize(byte[] data) throws Exception {
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if (!Arrays.equals(Arrays.copyOfRange(data, 0, 8),
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"ANDROID!".getBytes("US-ASCII"))) {
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throw new IllegalArgumentException("Invalid image header: missing magic");
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}
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ByteBuffer image = ByteBuffer.wrap(data);
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image.order(ByteOrder.LITTLE_ENDIAN);
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image.getLong(); // magic
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int kernelSize = image.getInt();
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image.getInt(); // kernel_addr
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int ramdskSize = image.getInt();
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image.getInt(); // ramdisk_addr
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int secondSize = image.getInt();
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image.getLong(); // second_addr + tags_addr
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int pageSize = image.getInt();
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int dtSize = image.getInt(); // dt_size
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int length = pageSize // include the page aligned image header
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+ ((kernelSize + pageSize - 1) / pageSize) * pageSize
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+ ((ramdskSize + pageSize - 1) / pageSize) * pageSize
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+ ((secondSize + pageSize - 1) / pageSize) * pageSize
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+ ((dtSize + pageSize - 1) / pageSize) * pageSize;
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length = ((length + pageSize - 1) / pageSize) * pageSize;
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if (length <= 0) {
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throw new IllegalArgumentException("Invalid image header: invalid length");
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}
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return length;
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}
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public static void doSignature( String target,
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String imagePath,
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String keyPath,
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String certPath,
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String outPath) throws Exception {
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byte[] image = Utils.read(imagePath);
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int signableSize = getSignableImageSize(image);
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if (signableSize < image.length) {
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System.err.println("NOTE: truncating file " + imagePath +
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" from " + image.length + " to " + signableSize + " bytes");
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image = Arrays.copyOf(image, signableSize);
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} else if (signableSize > image.length) {
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throw new IllegalArgumentException("Invalid image: too short, expected " +
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signableSize + " bytes");
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}
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BootSignature bootsig = new BootSignature(target, image.length);
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X509Certificate cert = Utils.loadPEMCertificate(certPath);
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bootsig.setCertificate(cert);
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PrivateKey key = Utils.loadDERPrivateKeyFromFile(keyPath);
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bootsig.setSignature(bootsig.sign(image, key),
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Utils.getSignatureAlgorithmIdentifier(key));
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byte[] encoded_bootsig = bootsig.getEncoded();
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byte[] image_with_metadata = Arrays.copyOf(image, image.length + encoded_bootsig.length);
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System.arraycopy(encoded_bootsig, 0, image_with_metadata,
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image.length, encoded_bootsig.length);
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Utils.write(image_with_metadata, outPath);
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}
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public static void verifySignature(String imagePath) throws Exception {
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byte[] image = Utils.read(imagePath);
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int signableSize = getSignableImageSize(image);
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if (signableSize >= image.length) {
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throw new IllegalArgumentException("Invalid image: not signed");
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}
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byte[] signature = Arrays.copyOfRange(image, signableSize, image.length);
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BootSignature bootsig = new BootSignature(signature);
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try {
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if (bootsig.verify(Arrays.copyOf(image, signableSize))) {
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System.err.println("Signature is VALID");
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System.exit(0);
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} else {
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System.err.println("Signature is INVALID");
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}
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} catch (Exception e) {
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e.printStackTrace(System.err);
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}
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System.exit(1);
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}
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/* Example usage for signing a boot image using dev keys:
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java -cp \
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../../../out/host/common/obj/JAVA_LIBRARIES/BootSignature_intermediates/ \
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classes/com.android.verity.BootSignature \
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/boot \
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../../../out/target/product/$PRODUCT/boot.img \
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../../../build/target/product/security/verity.pk8 \
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../../../build/target/product/security/verity.x509.pem \
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/tmp/boot.img.signed
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*/
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public static void main(String[] args) throws Exception {
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Security.addProvider(new BouncyCastleProvider());
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if ("-verify".equals(args[0])) {
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/* args[1] is the path to a signed boot image */
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verifySignature(args[1]);
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} else {
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/* args[0] is the target name, typically /boot
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args[1] is the path to a boot image to sign
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args[2] is the path to a private key
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args[3] is the path to the matching public key certificate
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args[4] is the path where to output the signed boot image
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*/
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doSignature(args[0], args[1], args[2], args[3], args[4]);
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}
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}
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}
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