2023-11-29 22:32:00 -06:00

324 lines
12 KiB
Java

package com.limelight.nvstream.http;
import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.engines.AESLightEngine;
import org.bouncycastle.crypto.params.KeyParameter;
import org.xmlpull.v1.XmlPullParserException;
import com.limelight.LimeLog;
import java.security.cert.Certificate;
import java.io.*;
import java.security.*;
import java.security.cert.*;
import java.util.Arrays;
import java.util.Locale;
public class PairingManager {
private NvHTTP http;
private PrivateKey pk;
private X509Certificate cert;
private byte[] pemCertBytes;
private X509Certificate serverCert;
public enum PairState {
NOT_PAIRED,
PAIRED,
PIN_WRONG,
FAILED,
ALREADY_IN_PROGRESS
}
public PairingManager(NvHTTP http, LimelightCryptoProvider cryptoProvider) {
this.http = http;
this.cert = cryptoProvider.getClientCertificate();
this.pemCertBytes = cryptoProvider.getPemEncodedClientCertificate();
this.pk = cryptoProvider.getClientPrivateKey();
}
final private static char[] hexArray = "0123456789ABCDEF".toCharArray();
private static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for ( int j = 0; j < bytes.length; j++ ) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
private static byte[] hexToBytes(String s) {
int len = s.length();
if (len % 2 != 0) {
throw new IllegalArgumentException("Illegal string length: "+len);
}
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
private X509Certificate extractPlainCert(String text) throws XmlPullParserException, IOException
{
// Plaincert may be null if another client is already trying to pair
String certText = NvHTTP.getXmlString(text, "plaincert", false);
if (certText != null) {
byte[] certBytes = hexToBytes(certText);
try {
CertificateFactory cf = CertificateFactory.getInstance("X.509");
return (X509Certificate)cf.generateCertificate(new ByteArrayInputStream(certBytes));
} catch (CertificateException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
else {
return null;
}
}
private byte[] generateRandomBytes(int length)
{
byte[] rand = new byte[length];
new SecureRandom().nextBytes(rand);
return rand;
}
private static byte[] saltPin(byte[] salt, String pin) throws UnsupportedEncodingException {
byte[] saltedPin = new byte[salt.length + pin.length()];
System.arraycopy(salt, 0, saltedPin, 0, salt.length);
System.arraycopy(pin.getBytes("UTF-8"), 0, saltedPin, salt.length, pin.length());
return saltedPin;
}
private static boolean verifySignature(byte[] data, byte[] signature, Certificate cert) {
try {
Signature sig = Signature.getInstance("SHA256withRSA");
sig.initVerify(cert.getPublicKey());
sig.update(data);
return sig.verify(signature);
} catch (NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private static byte[] signData(byte[] data, PrivateKey key) {
try {
Signature sig = Signature.getInstance("SHA256withRSA");
sig.initSign(key);
sig.update(data);
return sig.sign();
} catch (NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private static byte[] performBlockCipher(BlockCipher blockCipher, byte[] input) {
int blockSize = blockCipher.getBlockSize();
int blockRoundedSize = (input.length + (blockSize - 1)) & ~(blockSize - 1);
byte[] blockRoundedInputData = Arrays.copyOf(input, blockRoundedSize);
byte[] blockRoundedOutputData = new byte[blockRoundedSize];
for (int offset = 0; offset < blockRoundedSize; offset += blockSize) {
blockCipher.processBlock(blockRoundedInputData, offset, blockRoundedOutputData, offset);
}
return blockRoundedOutputData;
}
private static byte[] decryptAes(byte[] encryptedData, byte[] aesKey) {
BlockCipher aesEngine = new AESLightEngine();
aesEngine.init(false, new KeyParameter(aesKey));
return performBlockCipher(aesEngine, encryptedData);
}
private static byte[] encryptAes(byte[] plaintextData, byte[] aesKey) {
BlockCipher aesEngine = new AESLightEngine();
aesEngine.init(true, new KeyParameter(aesKey));
return performBlockCipher(aesEngine, plaintextData);
}
private static byte[] generateAesKey(PairingHashAlgorithm hashAlgo, byte[] keyData) {
return Arrays.copyOf(hashAlgo.hashData(keyData), 16);
}
private static byte[] concatBytes(byte[] a, byte[] b) {
byte[] c = new byte[a.length + b.length];
System.arraycopy(a, 0, c, 0, a.length);
System.arraycopy(b, 0, c, a.length, b.length);
return c;
}
public static String generatePinString() {
SecureRandom r = new SecureRandom();
return String.format((Locale)null, "%d%d%d%d",
r.nextInt(10), r.nextInt(10),
r.nextInt(10), r.nextInt(10));
}
public X509Certificate getPairedCert() {
return serverCert;
}
public PairState pair(String serverInfo, String pin) throws IOException, XmlPullParserException {
PairingHashAlgorithm hashAlgo;
int serverMajorVersion = http.getServerMajorVersion(serverInfo);
LimeLog.info("Pairing with server generation: "+serverMajorVersion);
if (serverMajorVersion >= 7) {
// Gen 7+ uses SHA-256 hashing
hashAlgo = new Sha256PairingHash();
}
else {
// Prior to Gen 7, SHA-1 is used
hashAlgo = new Sha1PairingHash();
}
// Generate a salt for hashing the PIN
byte[] salt = generateRandomBytes(16);
// Combine the salt and pin, then create an AES key from them
byte[] aesKey = generateAesKey(hashAlgo, saltPin(salt, pin));
// Send the salt and get the server cert. This doesn't have a read timeout
// because the user must enter the PIN before the server responds
String getCert = http.executePairingCommand("phrase=getservercert&salt="+
bytesToHex(salt)+"&clientcert="+bytesToHex(pemCertBytes),
false);
if (!NvHTTP.getXmlString(getCert, "paired", true).equals("1")) {
return PairState.FAILED;
}
// Save this cert for retrieval later
serverCert = extractPlainCert(getCert);
if (serverCert == null) {
// Attempting to pair while another device is pairing will cause GFE
// to give an empty cert in the response.
http.unpair();
return PairState.ALREADY_IN_PROGRESS;
}
// Require this cert for TLS to this host
http.setServerCert(serverCert);
// Generate a random challenge and encrypt it with our AES key
byte[] randomChallenge = generateRandomBytes(16);
byte[] encryptedChallenge = encryptAes(randomChallenge, aesKey);
// Send the encrypted challenge to the server
String challengeResp = http.executePairingCommand("clientchallenge="+bytesToHex(encryptedChallenge), true);
if (!NvHTTP.getXmlString(challengeResp, "paired", true).equals("1")) {
http.unpair();
return PairState.FAILED;
}
// Decode the server's response and subsequent challenge
byte[] encServerChallengeResponse = hexToBytes(NvHTTP.getXmlString(challengeResp, "challengeresponse", true));
byte[] decServerChallengeResponse = decryptAes(encServerChallengeResponse, aesKey);
byte[] serverResponse = Arrays.copyOfRange(decServerChallengeResponse, 0, hashAlgo.getHashLength());
byte[] serverChallenge = Arrays.copyOfRange(decServerChallengeResponse, hashAlgo.getHashLength(), hashAlgo.getHashLength() + 16);
// Using another 16 bytes secret, compute a challenge response hash using the secret, our cert sig, and the challenge
byte[] clientSecret = generateRandomBytes(16);
byte[] challengeRespHash = hashAlgo.hashData(concatBytes(concatBytes(serverChallenge, cert.getSignature()), clientSecret));
byte[] challengeRespEncrypted = encryptAes(challengeRespHash, aesKey);
String secretResp = http.executePairingCommand("serverchallengeresp="+bytesToHex(challengeRespEncrypted), true);
if (!NvHTTP.getXmlString(secretResp, "paired", true).equals("1")) {
http.unpair();
return PairState.FAILED;
}
// Get the server's signed secret
byte[] serverSecretResp = hexToBytes(NvHTTP.getXmlString(secretResp, "pairingsecret", true));
byte[] serverSecret = Arrays.copyOfRange(serverSecretResp, 0, 16);
byte[] serverSignature = Arrays.copyOfRange(serverSecretResp, 16, serverSecretResp.length);
// Ensure the authenticity of the data
if (!verifySignature(serverSecret, serverSignature, serverCert)) {
// Cancel the pairing process
http.unpair();
// Looks like a MITM
return PairState.FAILED;
}
// Ensure the server challenge matched what we expected (aka the PIN was correct)
byte[] serverChallengeRespHash = hashAlgo.hashData(concatBytes(concatBytes(randomChallenge, serverCert.getSignature()), serverSecret));
if (!Arrays.equals(serverChallengeRespHash, serverResponse)) {
// Cancel the pairing process
http.unpair();
// Probably got the wrong PIN
return PairState.PIN_WRONG;
}
// Send the server our signed secret
byte[] clientPairingSecret = concatBytes(clientSecret, signData(clientSecret, pk));
String clientSecretResp = http.executePairingCommand("clientpairingsecret="+bytesToHex(clientPairingSecret), true);
if (!NvHTTP.getXmlString(clientSecretResp, "paired", true).equals("1")) {
http.unpair();
return PairState.FAILED;
}
// Do the initial challenge (seems necessary for us to show as paired)
String pairChallenge = http.executePairingChallenge();
if (!NvHTTP.getXmlString(pairChallenge, "paired", true).equals("1")) {
http.unpair();
return PairState.FAILED;
}
return PairState.PAIRED;
}
private interface PairingHashAlgorithm {
int getHashLength();
byte[] hashData(byte[] data);
}
private static class Sha1PairingHash implements PairingHashAlgorithm {
public int getHashLength() {
return 20;
}
public byte[] hashData(byte[] data) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-1");
return md.digest(data);
}
catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
private static class Sha256PairingHash implements PairingHashAlgorithm {
public int getHashLength() {
return 32;
}
public byte[] hashData(byte[] data) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
return md.digest(data);
}
catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
}