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/*
* Copyright 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.signtos;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.lang.reflect.Constructor;
import java.security.GeneralSecurityException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.MessageDigest;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.PublicKey;
import java.security.Security;
import java.security.Signature;
import java.security.interfaces.ECKey;
import java.security.interfaces.ECPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.EncryptedPrivateKeyInfo;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
/**
* Signs Trusty images for use with operating systems that support it.
*/
public class SignTos {
/** Size of the signature footer in bytes. */
private static final int SIGNATURE_BLOCK_SIZE = 256;
/** Current signature version code we use. */
private static final int VERSION_CODE = 1;
/** Size of the header on the file to skip. */
private static final int HEADER_SIZE = 512;
private static BouncyCastleProvider sBouncyCastleProvider;
/**
* Reads the password from stdin and returns it as a string.
*
* @param keyFile The file containing the private key. Used to prompt the user.
*/
private static String readPassword(File keyFile) {
// TODO: use Console.readPassword() when it's available.
System.out.print("Enter password for " + keyFile + " (password will not be hidden): ");
System.out.flush();
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
try {
return stdin.readLine();
} catch (IOException ex) {
return null;
}
}
/**
* Decrypt an encrypted PKCS#8 format private key.
*
* Based on ghstark's post on Aug 6, 2006 at
* http://forums.sun.com/thread.jspa?threadID=758133&messageID=4330949
*
* @param encryptedPrivateKey The raw data of the private key
* @param keyFile The file containing the private key
*/
private static PKCS8EncodedKeySpec decryptPrivateKey(byte[] encryptedPrivateKey, File keyFile)
throws GeneralSecurityException {
EncryptedPrivateKeyInfo epkInfo;
try {
epkInfo = new EncryptedPrivateKeyInfo(encryptedPrivateKey);
} catch (IOException ex) {
// Probably not an encrypted key.
return null;
}
char[] password = readPassword(keyFile).toCharArray();
SecretKeyFactory skFactory = SecretKeyFactory.getInstance(epkInfo.getAlgName());
Key key = skFactory.generateSecret(new PBEKeySpec(password));
Cipher cipher = Cipher.getInstance(epkInfo.getAlgName());
cipher.init(Cipher.DECRYPT_MODE, key, epkInfo.getAlgParameters());
try {
return epkInfo.getKeySpec(cipher);
} catch (InvalidKeySpecException ex) {
System.err.println("signapk: Password for " + keyFile + " may be bad.");
throw ex;
}
}
/** Read a PKCS#8 format private key. */
private static PrivateKey readPrivateKey(File file) throws IOException,
GeneralSecurityException {
DataInputStream input = new DataInputStream(new FileInputStream(file));
try {
byte[] bytes = new byte[(int) file.length()];
input.read(bytes);
/* Check to see if this is in an EncryptedPrivateKeyInfo structure. */
PKCS8EncodedKeySpec spec = decryptPrivateKey(bytes, file);
if (spec == null) {
spec = new PKCS8EncodedKeySpec(bytes);
}
/*
* Now it's in a PKCS#8 PrivateKeyInfo structure. Read its Algorithm
* OID and use that to construct a KeyFactory.
*/
ASN1InputStream bIn = new ASN1InputStream(new ByteArrayInputStream(spec.getEncoded()));
PrivateKeyInfo pki = PrivateKeyInfo.getInstance(bIn.readObject());
String algOid = pki.getPrivateKeyAlgorithm().getAlgorithm().getId();
return KeyFactory.getInstance(algOid).generatePrivate(spec);
} finally {
input.close();
}
}
/**
* Tries to load a JSE Provider by class name. This is for custom PrivateKey
* types that might be stored in PKCS#11-like storage.
*/
private static void loadProviderIfNecessary(String providerClassName) {
if (providerClassName == null) {
return;
}
final Class<?> klass;
try {
final ClassLoader sysLoader = ClassLoader.getSystemClassLoader();
if (sysLoader != null) {
klass = sysLoader.loadClass(providerClassName);
} else {
klass = Class.forName(providerClassName);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
System.exit(1);
return;
}
Constructor<?> constructor = null;
for (Constructor<?> c : klass.getConstructors()) {
if (c.getParameterTypes().length == 0) {
constructor = c;
break;
}
}
if (constructor == null) {
System.err.println("No zero-arg constructor found for " + providerClassName);
System.exit(1);
return;
}
final Object o;
try {
o = constructor.newInstance();
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
return;
}
if (!(o instanceof Provider)) {
System.err.println("Not a Provider class: " + providerClassName);
System.exit(1);
}
Security.insertProviderAt((Provider) o, 1);
}
private static String getSignatureAlgorithm(Key key) {
if ("EC".equals(key.getAlgorithm())) {
ECKey ecKey = (ECKey) key;
int curveSize = ecKey.getParams().getOrder().bitLength();
if (curveSize <= 256) {
return "SHA256withECDSA";
} else if (curveSize <= 384) {
return "SHA384withECDSA";
} else {
return "SHA512withECDSA";
}
} else {
throw new IllegalArgumentException("Unsupported key type " + key.getAlgorithm());
}
}
/**
* @param inputFilename
* @param outputFilename
*/
private static void signWholeFile(InputStream input, OutputStream output, PrivateKey signingKey)
throws Exception {
Signature sig = Signature.getInstance(getSignatureAlgorithm(signingKey));
sig.initSign(signingKey);
byte[] buffer = new byte[8192];
/* Skip the header. */
int skippedBytes = 0;
while (skippedBytes != HEADER_SIZE) {
int bytesRead = input.read(buffer, 0, HEADER_SIZE - skippedBytes);
output.write(buffer, 0, bytesRead);
skippedBytes += bytesRead;
}
int totalBytes = 0;
for (;;) {
int bytesRead = input.read(buffer);
if (bytesRead == -1) {
break;
}
totalBytes += bytesRead;
sig.update(buffer, 0, bytesRead);
output.write(buffer, 0, bytesRead);
}
byte[] sigBlock = new byte[SIGNATURE_BLOCK_SIZE];
sigBlock[0] = VERSION_CODE;
sig.sign(sigBlock, 1, sigBlock.length - 1);
output.write(sigBlock);
}
private static void usage() {
System.err.println("Usage: signtos " +
"[-providerClass <className>] " +
" privatekey.pk8 " +
"input.img output.img");
System.exit(2);
}
public static void main(String[] args) throws Exception {
if (args.length < 3) {
usage();
}
String providerClass = null;
String providerArg = null;
int argstart = 0;
while (argstart < args.length && args[argstart].startsWith("-")) {
if ("-providerClass".equals(args[argstart])) {
if (argstart + 1 >= args.length) {
usage();
}
providerClass = args[++argstart];
++argstart;
} else {
usage();
}
}
/*
* Should only be "<privatekey> <input> <output>" left.
*/
if (argstart != args.length - 3) {
usage();
}
sBouncyCastleProvider = new BouncyCastleProvider();
Security.addProvider(sBouncyCastleProvider);
loadProviderIfNecessary(providerClass);
String keyFilename = args[args.length - 3];
String inputFilename = args[args.length - 2];
String outputFilename = args[args.length - 1];
PrivateKey privateKey = readPrivateKey(new File(keyFilename));
InputStream input = new BufferedInputStream(new FileInputStream(inputFilename));
OutputStream output = new BufferedOutputStream(new FileOutputStream(outputFilename));
try {
SignTos.signWholeFile(input, output, privateKey);
} finally {
input.close();
output.close();
}
System.out.println("Successfully signed: " + outputFilename);
}
}