verity/BootSignature.java - platform/system/extras - Git at Google

 /*
  * Copyright (C) 2014 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 com.android.verity;

 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.Security;
 import java.security.cert.X509Certificate;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateFactory;
 import java.security.cert.CertificateEncodingException;
 import java.util.Arrays;
 import org.bouncycastle.asn1.ASN1Encodable;
 import org.bouncycastle.asn1.ASN1EncodableVector;
 import org.bouncycastle.asn1.ASN1Integer;
 import org.bouncycastle.asn1.ASN1Object;
 import org.bouncycastle.asn1.ASN1ObjectIdentifier;
 import org.bouncycastle.asn1.ASN1OctetString;
 import org.bouncycastle.asn1.ASN1Primitive;
 import org.bouncycastle.asn1.ASN1Sequence;
 import org.bouncycastle.asn1.ASN1InputStream;
 import org.bouncycastle.asn1.DEROctetString;
 import org.bouncycastle.asn1.DERPrintableString;
 import org.bouncycastle.asn1.DERSequence;
 import org.bouncycastle.asn1.util.ASN1Dump;
 import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
 import org.bouncycastle.jce.provider.BouncyCastleProvider;

 /**
  *    AndroidVerifiedBootSignature DEFINITIONS ::=
  *    BEGIN
  *        formatVersion ::= INTEGER
  *        certificate ::= Certificate
  *        algorithmIdentifier ::= SEQUENCE {
  *            algorithm OBJECT IDENTIFIER,
  *            parameters ANY DEFINED BY algorithm OPTIONAL
  *        }
  *        authenticatedAttributes ::= SEQUENCE {
  *            target CHARACTER STRING,
  *            length INTEGER
  *        }
  *        signature ::= OCTET STRING
  *     END
  */

 public class BootSignature extends ASN1Object
 {
     private ASN1Integer             formatVersion;
     private ASN1Encodable           certificate;
     private AlgorithmIdentifier     algorithmIdentifier;
     private DERPrintableString      target;
     private ASN1Integer             length;
     private DEROctetString          signature;
     private PublicKey               publicKey;

     private static final int FORMAT_VERSION = 1;

     /**
      * Initializes the object for signing an image file
      * @param target Target name, included in the signed data
      * @param length Length of the image, included in the signed data
      */
     public BootSignature(String target, int length) {
         this.formatVersion = new ASN1Integer(FORMAT_VERSION);
         this.target = new DERPrintableString(target);
         this.length = new ASN1Integer(length);
     }

     /**
      * Initializes the object for verifying a signed image file
      * @param signature Signature footer
      */
     public BootSignature(byte[] signature)
             throws Exception {
         ASN1InputStream stream = new ASN1InputStream(signature);
         ASN1Sequence sequence = (ASN1Sequence) stream.readObject();

         formatVersion = (ASN1Integer) sequence.getObjectAt(0);
         if (formatVersion.getValue().intValue() != FORMAT_VERSION) {
             throw new IllegalArgumentException("Unsupported format version");
         }

         certificate = sequence.getObjectAt(1);
         byte[] encoded = ((ASN1Object) certificate).getEncoded();
         ByteArrayInputStream bis = new ByteArrayInputStream(encoded);

         CertificateFactory cf = CertificateFactory.getInstance("X.509");
         X509Certificate c = (X509Certificate) cf.generateCertificate(bis);
         publicKey = c.getPublicKey();

         ASN1Sequence algId = (ASN1Sequence) sequence.getObjectAt(2);
         algorithmIdentifier = new AlgorithmIdentifier(
             (ASN1ObjectIdentifier) algId.getObjectAt(0));

         ASN1Sequence attrs = (ASN1Sequence) sequence.getObjectAt(3);
         target = (DERPrintableString) attrs.getObjectAt(0);
         length = (ASN1Integer) attrs.getObjectAt(1);

         this.signature = (DEROctetString) sequence.getObjectAt(4);
     }

     public ASN1Object getAuthenticatedAttributes() {
         ASN1EncodableVector attrs = new ASN1EncodableVector();
         attrs.add(target);
         attrs.add(length);
         return new DERSequence(attrs);
     }

     public byte[] getEncodedAuthenticatedAttributes() throws IOException {
         return getAuthenticatedAttributes().getEncoded();
     }

     public AlgorithmIdentifier getAlgorithmIdentifier() {
         return algorithmIdentifier;
     }

     public PublicKey getPublicKey() {
         return publicKey;
     }

     public byte[] getSignature() {
         return signature.getOctets();
     }

     public void setSignature(byte[] sig, AlgorithmIdentifier algId) {
         algorithmIdentifier = algId;
         signature = new DEROctetString(sig);
     }

     public void setCertificate(X509Certificate cert)
             throws Exception, IOException, CertificateEncodingException {
         ASN1InputStream s = new ASN1InputStream(cert.getEncoded());
         certificate = s.readObject();
     }

     public byte[] generateSignableImage(byte[] image) throws IOException {
         byte[] attrs = getEncodedAuthenticatedAttributes();
         byte[] signable = Arrays.copyOf(image, image.length + attrs.length);
         for (int i=0; i < attrs.length; i++) {
             signable[i+image.length] = attrs[i];
         }
         return signable;
     }

     public byte[] sign(byte[] image, PrivateKey key) throws Exception {
         byte[] signable = generateSignableImage(image);
         return Utils.sign(key, signable);
     }

     public boolean verify(byte[] image) throws Exception {
         if (length.getValue().intValue() != image.length) {
             throw new IllegalArgumentException("Invalid image length");
         }

         byte[] signable = generateSignableImage(image);
         return Utils.verify(publicKey, signable, signature.getOctets(),
                     algorithmIdentifier);
     }

     public ASN1Primitive toASN1Primitive() {
         ASN1EncodableVector v = new ASN1EncodableVector();
         v.add(formatVersion);
         v.add(certificate);
         v.add(algorithmIdentifier);
         v.add(getAuthenticatedAttributes());
         v.add(signature);
         return new DERSequence(v);
     }

     public static int getSignableImageSize(byte[] data) throws Exception {
         if (!Arrays.equals(Arrays.copyOfRange(data, 0, 8),
                 "ANDROID!".getBytes("US-ASCII"))) {
             throw new IllegalArgumentException("Invalid image header: missing magic");
         }

         ByteBuffer image = ByteBuffer.wrap(data);
         image.order(ByteOrder.LITTLE_ENDIAN);

         image.getLong(); // magic
         int kernelSize = image.getInt();
         image.getInt(); // kernel_addr
         int ramdskSize = image.getInt();
         image.getInt(); // ramdisk_addr
         int secondSize = image.getInt();
         image.getLong(); // second_addr + tags_addr
         int pageSize = image.getInt();

         int length = pageSize // include the page aligned image header
                 + ((kernelSize + pageSize - 1) / pageSize) * pageSize
                 + ((ramdskSize + pageSize - 1) / pageSize) * pageSize
                 + ((secondSize + pageSize - 1) / pageSize) * pageSize;

         length = ((length + pageSize - 1) / pageSize) * pageSize;

         if (length <= 0) {
             throw new IllegalArgumentException("Invalid image header: invalid length");
         }

         return length;
     }

     public static void doSignature( String target,
                                     String imagePath,
                                     String keyPath,
                                     String certPath,
                                     String outPath) throws Exception {

         byte[] image = Utils.read(imagePath);
         int signableSize = getSignableImageSize(image);

         if (signableSize < image.length) {
             System.err.println("NOTE: truncating file " + imagePath +
                     " from " + image.length + " to " + signableSize + " bytes");
             image = Arrays.copyOf(image, signableSize);
         } else if (signableSize > image.length) {
             throw new IllegalArgumentException("Invalid image: too short, expected " +
                     signableSize + " bytes");
         }

         BootSignature bootsig = new BootSignature(target, image.length);

         X509Certificate cert = Utils.loadPEMCertificate(certPath);
         bootsig.setCertificate(cert);

         PrivateKey key = Utils.loadDERPrivateKeyFromFile(keyPath);
         bootsig.setSignature(bootsig.sign(image, key),
             Utils.getSignatureAlgorithmIdentifier(key));

         byte[] encoded_bootsig = bootsig.getEncoded();
         byte[] image_with_metadata = Arrays.copyOf(image, image.length + encoded_bootsig.length);

         System.arraycopy(encoded_bootsig, 0, image_with_metadata,
                 image.length, encoded_bootsig.length);

         Utils.write(image_with_metadata, outPath);
     }

     public static void verifySignature(String imagePath) throws Exception {
         byte[] image = Utils.read(imagePath);
         int signableSize = getSignableImageSize(image);

         if (signableSize >= image.length) {
             throw new IllegalArgumentException("Invalid image: not signed");
         }

         byte[] signature = Arrays.copyOfRange(image, signableSize, image.length);
         BootSignature bootsig = new BootSignature(signature);

         try {
             if (bootsig.verify(Arrays.copyOf(image, signableSize))) {
                 System.err.println("Signature is VALID");
                 System.exit(0);
             } else {
                 System.err.println("Signature is INVALID");
             }
         } catch (Exception e) {
             e.printStackTrace(System.err);
         }
         System.exit(1);
     }

     /* Example usage for signing a boot image using dev keys:
         java -cp \
             ../../../out/host/common/obj/JAVA_LIBRARIES/BootSignature_intermediates/ \
                 classes/com.android.verity.BootSignature \
             /boot \
             ../../../out/target/product/$PRODUCT/boot.img \
             ../../../build/target/product/security/verity.pk8 \
             ../../../build/target/product/security/verity.x509.pem \
             /tmp/boot.img.signed
     */
     public static void main(String[] args) throws Exception {
         Security.addProvider(new BouncyCastleProvider());

         if ("-verify".equals(args[0])) {
             /* args[1] is the path to a signed boot image */
             verifySignature(args[1]);
         } else {
             /* args[0] is the target name, typically /boot
                args[1] is the path to a boot image to sign
                args[2] is the path to a private key
                args[3] is the path to the matching public key certificate
                args[4] is the path where to output the signed boot image
             */
             doSignature(args[0], args[1], args[2], args[3], args[4]);
         }
     }
 }
	/*
	* Copyright (C) 2014 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 com.android.verity;

	import java.io.ByteArrayInputStream;
	import java.io.IOException;
	import java.nio.ByteBuffer;
	import java.nio.ByteOrder;
	import java.security.PrivateKey;
	import java.security.PublicKey;
	import java.security.Security;
	import java.security.cert.X509Certificate;
	import java.security.cert.Certificate;
	import java.security.cert.CertificateFactory;
	import java.security.cert.CertificateEncodingException;
	import java.util.Arrays;
	import org.bouncycastle.asn1.ASN1Encodable;
	import org.bouncycastle.asn1.ASN1EncodableVector;
	import org.bouncycastle.asn1.ASN1Integer;
	import org.bouncycastle.asn1.ASN1Object;
	import org.bouncycastle.asn1.ASN1ObjectIdentifier;
	import org.bouncycastle.asn1.ASN1OctetString;
	import org.bouncycastle.asn1.ASN1Primitive;
	import org.bouncycastle.asn1.ASN1Sequence;
	import org.bouncycastle.asn1.ASN1InputStream;
	import org.bouncycastle.asn1.DEROctetString;
	import org.bouncycastle.asn1.DERPrintableString;
	import org.bouncycastle.asn1.DERSequence;
	import org.bouncycastle.asn1.util.ASN1Dump;
	import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
	import org.bouncycastle.jce.provider.BouncyCastleProvider;

	/**
	* AndroidVerifiedBootSignature DEFINITIONS ::=
	* BEGIN
	* formatVersion ::= INTEGER
	* certificate ::= Certificate
	* algorithmIdentifier ::= SEQUENCE {
	* algorithm OBJECT IDENTIFIER,
	* parameters ANY DEFINED BY algorithm OPTIONAL
	* }
	* authenticatedAttributes ::= SEQUENCE {
	* target CHARACTER STRING,
	* length INTEGER
	* }
	* signature ::= OCTET STRING
	* END
	*/

	public class BootSignature extends ASN1Object
	{
	private ASN1Integer formatVersion;
	private ASN1Encodable certificate;
	private AlgorithmIdentifier algorithmIdentifier;
	private DERPrintableString target;
	private ASN1Integer length;
	private DEROctetString signature;
	private PublicKey publicKey;

	private static final int FORMAT_VERSION = 1;

	/**
	* Initializes the object for signing an image file
	* @param target Target name, included in the signed data
	* @param length Length of the image, included in the signed data
	*/
	public BootSignature(String target, int length) {
	this.formatVersion = new ASN1Integer(FORMAT_VERSION);
	this.target = new DERPrintableString(target);
	this.length = new ASN1Integer(length);
	}

	/**
	* Initializes the object for verifying a signed image file
	* @param signature Signature footer
	*/
	public BootSignature(byte[] signature)
	throws Exception {
	ASN1InputStream stream = new ASN1InputStream(signature);
	ASN1Sequence sequence = (ASN1Sequence) stream.readObject();

	formatVersion = (ASN1Integer) sequence.getObjectAt(0);
	if (formatVersion.getValue().intValue() != FORMAT_VERSION) {
	throw new IllegalArgumentException("Unsupported format version");
	}

	certificate = sequence.getObjectAt(1);
	byte[] encoded = ((ASN1Object) certificate).getEncoded();
	ByteArrayInputStream bis = new ByteArrayInputStream(encoded);

	CertificateFactory cf = CertificateFactory.getInstance("X.509");
	X509Certificate c = (X509Certificate) cf.generateCertificate(bis);
	publicKey = c.getPublicKey();

	ASN1Sequence algId = (ASN1Sequence) sequence.getObjectAt(2);
	algorithmIdentifier = new AlgorithmIdentifier(
	(ASN1ObjectIdentifier) algId.getObjectAt(0));

	ASN1Sequence attrs = (ASN1Sequence) sequence.getObjectAt(3);
	target = (DERPrintableString) attrs.getObjectAt(0);
	length = (ASN1Integer) attrs.getObjectAt(1);

	this.signature = (DEROctetString) sequence.getObjectAt(4);
	}

	public ASN1Object getAuthenticatedAttributes() {
	ASN1EncodableVector attrs = new ASN1EncodableVector();
	attrs.add(target);
	attrs.add(length);
	return new DERSequence(attrs);
	}

	public byte[] getEncodedAuthenticatedAttributes() throws IOException {
	return getAuthenticatedAttributes().getEncoded();
	}

	public AlgorithmIdentifier getAlgorithmIdentifier() {
	return algorithmIdentifier;
	}

	public PublicKey getPublicKey() {
	return publicKey;
	}

	public byte[] getSignature() {
	return signature.getOctets();
	}

	public void setSignature(byte[] sig, AlgorithmIdentifier algId) {
	algorithmIdentifier = algId;
	signature = new DEROctetString(sig);
	}

	public void setCertificate(X509Certificate cert)
	throws Exception, IOException, CertificateEncodingException {
	ASN1InputStream s = new ASN1InputStream(cert.getEncoded());
	certificate = s.readObject();
	}

	public byte[] generateSignableImage(byte[] image) throws IOException {
	byte[] attrs = getEncodedAuthenticatedAttributes();
	byte[] signable = Arrays.copyOf(image, image.length + attrs.length);
	for (int i=0; i < attrs.length; i++) {
	signable[i+image.length] = attrs[i];
	}
	return signable;
	}

	public byte[] sign(byte[] image, PrivateKey key) throws Exception {
	byte[] signable = generateSignableImage(image);
	return Utils.sign(key, signable);
	}

	public boolean verify(byte[] image) throws Exception {
	if (length.getValue().intValue() != image.length) {
	throw new IllegalArgumentException("Invalid image length");
	}

	byte[] signable = generateSignableImage(image);
	return Utils.verify(publicKey, signable, signature.getOctets(),
	algorithmIdentifier);
	}

	public ASN1Primitive toASN1Primitive() {
	ASN1EncodableVector v = new ASN1EncodableVector();
	v.add(formatVersion);
	v.add(certificate);
	v.add(algorithmIdentifier);
	v.add(getAuthenticatedAttributes());
	v.add(signature);
	return new DERSequence(v);
	}

	public static int getSignableImageSize(byte[] data) throws Exception {
	if (!Arrays.equals(Arrays.copyOfRange(data, 0, 8),
	"ANDROID!".getBytes("US-ASCII"))) {
	throw new IllegalArgumentException("Invalid image header: missing magic");
	}

	ByteBuffer image = ByteBuffer.wrap(data);
	image.order(ByteOrder.LITTLE_ENDIAN);

	image.getLong(); // magic
	int kernelSize = image.getInt();
	image.getInt(); // kernel_addr
	int ramdskSize = image.getInt();
	image.getInt(); // ramdisk_addr
	int secondSize = image.getInt();
	image.getLong(); // second_addr + tags_addr
	int pageSize = image.getInt();

	int length = pageSize // include the page aligned image header
	+ ((kernelSize + pageSize - 1) / pageSize) * pageSize
	+ ((ramdskSize + pageSize - 1) / pageSize) * pageSize
	+ ((secondSize + pageSize - 1) / pageSize) * pageSize;

	length = ((length + pageSize - 1) / pageSize) * pageSize;

	if (length <= 0) {
	throw new IllegalArgumentException("Invalid image header: invalid length");
	}

	return length;
	}

	public static void doSignature( String target,
	String imagePath,
	String keyPath,
	String certPath,
	String outPath) throws Exception {

	byte[] image = Utils.read(imagePath);
	int signableSize = getSignableImageSize(image);

	if (signableSize < image.length) {
	System.err.println("NOTE: truncating file " + imagePath +
	" from " + image.length + " to " + signableSize + " bytes");
	image = Arrays.copyOf(image, signableSize);
	} else if (signableSize > image.length) {
	throw new IllegalArgumentException("Invalid image: too short, expected " +
	signableSize + " bytes");
	}

	BootSignature bootsig = new BootSignature(target, image.length);

	X509Certificate cert = Utils.loadPEMCertificate(certPath);
	bootsig.setCertificate(cert);

	PrivateKey key = Utils.loadDERPrivateKeyFromFile(keyPath);
	bootsig.setSignature(bootsig.sign(image, key),
	Utils.getSignatureAlgorithmIdentifier(key));

	byte[] encoded_bootsig = bootsig.getEncoded();
	byte[] image_with_metadata = Arrays.copyOf(image, image.length + encoded_bootsig.length);

	System.arraycopy(encoded_bootsig, 0, image_with_metadata,
	image.length, encoded_bootsig.length);

	Utils.write(image_with_metadata, outPath);
	}

	public static void verifySignature(String imagePath) throws Exception {
	byte[] image = Utils.read(imagePath);
	int signableSize = getSignableImageSize(image);

	if (signableSize >= image.length) {
	throw new IllegalArgumentException("Invalid image: not signed");
	}

	byte[] signature = Arrays.copyOfRange(image, signableSize, image.length);
	BootSignature bootsig = new BootSignature(signature);

	try {
	if (bootsig.verify(Arrays.copyOf(image, signableSize))) {
	System.err.println("Signature is VALID");
	System.exit(0);
	} else {
	System.err.println("Signature is INVALID");
	}
	} catch (Exception e) {
	e.printStackTrace(System.err);
	}
	System.exit(1);
	}

	/* Example usage for signing a boot image using dev keys:
	java -cp \
	../../../out/host/common/obj/JAVA_LIBRARIES/BootSignature_intermediates/ \
	classes/com.android.verity.BootSignature \
	/boot \
	../../../out/target/product/$PRODUCT/boot.img \
	../../../build/target/product/security/verity.pk8 \
	../../../build/target/product/security/verity.x509.pem \
	/tmp/boot.img.signed
	*/
	public static void main(String[] args) throws Exception {
	Security.addProvider(new BouncyCastleProvider());

	if ("-verify".equals(args[0])) {
	/* args[1] is the path to a signed boot image */
	verifySignature(args[1]);
	} else {
	/* args[0] is the target name, typically /boot
	args[1] is the path to a boot image to sign
	args[2] is the path to a private key
	args[3] is the path to the matching public key certificate
	args[4] is the path where to output the signed boot image
	*/
	doSignature(args[0], args[1], args[2], args[3], args[4]);
	}
	}
	}