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Complete AuthKey generation process 

It works sometimes. Probably due to unsigned mistakes (50% chance)
This commit is contained in:
Lonami Exo 2018-07-24 16:07:51 +02:00
parent e404594ad5
commit 0a4abdcd36
5 changed files with 252 additions and 2 deletions
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40
lib/src/main/java/io/github/lonamiwebs/overgram/crypto/AuthKey.java Normal file
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@ -0,0 +1,40 @@
package io.github.lonamiwebs.overgram.crypto;
import io.github.lonamiwebs.overgram.utils.Utils;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
public class AuthKey {
public final byte[] key;
public final long auxHash;
public final long keyId;
public AuthKey(final byte[] key) {
this.key = key;
final ByteBuffer digest = ByteBuffer.wrap(Utils.sha1digest(key)).order(ByteOrder.LITTLE_ENDIAN);
auxHash = digest.getLong();
digest.position(digest.position() + 4);
keyId = digest.getLong();
}
public BigInteger calcNewNonceHash(final BigInteger newNonce, final int number) {
// Big integer is big endian but we need little endian
final byte[] data = Utils.sha1digest(Utils.concat(
Utils.reversed(newNonce.toByteArray()), Utils.concat(
ByteBuffer.allocate(1).put((byte) number).array(),
ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(auxHash).array()
)
));
// Little endian once again so read (20..4]
final byte[] numberBytes = new byte[16];
for (int i = 16; i-- != 0; ) {
numberBytes[i] = data[19 - i];
}
return new BigInteger(numberBytes);
}
}

81
lib/src/main/java/io/github/lonamiwebs/overgram/crypto/Authenticator.java
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@ -4,16 +4,19 @@ import io.github.lonamiwebs.overgram.network.MTProtoPlainSender;
import io.github.lonamiwebs.overgram.tl.Abstract;
import io.github.lonamiwebs.overgram.tl.Functions;
import io.github.lonamiwebs.overgram.tl.Types;
import io.github.lonamiwebs.overgram.utils.AES;
import io.github.lonamiwebs.overgram.utils.BinaryReader;
import io.github.lonamiwebs.overgram.utils.RSA;
import io.github.lonamiwebs.overgram.utils.Utils;
import javafx.util.Pair;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.ByteBuffer;
public class Authenticator {
public static void doAuthentication(final MTProtoPlainSender sender) throws IOException, ClassNotFoundException {
public static AuthKey doAuthentication(final MTProtoPlainSender sender) throws IOException, ClassNotFoundException {
final BigInteger nonce = new BigInteger(Utils.randomBytes(16));
final Types.ResPQ resPq = sender.send(
new Functions.ReqPqMulti().nonce(nonce));
@ -56,6 +59,7 @@ public class Authenticator {
throw new SecurityException("Step 2 could not find a known RSA key");
}
// TODO This *sometimes* fails, huh
final Abstract.ServerDHParams abstractDhParams = sender.send(
new Functions.ReqDHParams()
.nonce(resPq.nonce())
@ -76,7 +80,80 @@ public class Authenticator {
throw new SecurityException("Step 2 DH params have invalid nonce");
}
if (!dhParams.serverNonce().equals(resPq.serverNonce())) {
throw new SecurityException("Step 2 DH params have invalid nonce");
throw new SecurityException("Step 2 DH params have invalid server nonce");
}
if (dhParams.encryptedAnswer().length % 16 != 0) {
throw new SecurityException("Step 3 AES block size mismatch");
}
final Pair<byte[], byte[]> keyIv = Utils.generateKeyDataFromNonce(resPq.serverNonce(), newNonce);
final byte[] key = keyIv.getKey();
final byte[] iv = keyIv.getValue();
final byte[] plainText = AES.decryptIge(dhParams.encryptedAnswer(), key, iv);
final BinaryReader dhReader = new BinaryReader(ByteBuffer.wrap(plainText));
dhReader.seek(20); // hash sum
final Types.ServerDHInnerData dhInnerData = (Types.ServerDHInnerData) dhReader.readTl();
if (!dhInnerData.nonce().equals(resPq.nonce())) {
throw new SecurityException("Step 3 DH data have invalid nonce");
}
if (!dhInnerData.serverNonce().equals(resPq.serverNonce())) {
throw new SecurityException("Step 3 DH data have invalid server nonce");
}
// Big endian once again (and unsigned, so contact with a single zero byte)
final BigInteger dhPrime = new BigInteger(Utils.concat(new byte[1], dhInnerData.dhPrime()));
final BigInteger ga = new BigInteger(Utils.concat(new byte[1], dhInnerData.gA()));
final long timeOffset = dhInnerData.serverTime() - (System.currentTimeMillis() / 1000);
final byte[] bBytes = Utils.randomBytes(257);
bBytes[0] = 0;
final BigInteger b = new BigInteger(bBytes);
final BigInteger gb = new BigInteger(Integer.toString(dhInnerData.g())).modPow(b, dhPrime);
final BigInteger gab = ga.modPow(b, dhPrime);
final byte[] clientDhInnerData = new Types.ClientDHInnerData()
.nonce(resPq.nonce())
.serverNonce(resPq.serverNonce())
.retryId(0)
.gB(gb.toByteArray())
.serializeToBytes();
final byte[] clientDhInnerEncrypted = AES.encryptIge(Utils.concat(
Utils.sha1digest(clientDhInnerData), clientDhInnerData), key, iv);
final Abstract.SetClientDHParamsAnswer abstractDh = sender.send(
new Functions.SetClientDHParams()
.nonce(resPq.nonce())
.serverNonce(resPq.serverNonce())
.encryptedData(clientDhInnerEncrypted)
);
if (!(abstractDh instanceof Types.DhGenOk)) {
// Once again we could check the values for other types but it's invalid anyway
throw new SecurityException("Step 3 DH response was not OK");
}
final Types.DhGenOk dhGen = (Types.DhGenOk) abstractDh;
if (!dhGen.nonce().equals(resPq.nonce())) {
throw new SecurityException("Step 3 DH gen data have invalid nonce");
}
if (!dhGen.serverNonce().equals(resPq.serverNonce())) {
throw new SecurityException("Step 3 DH gen data have invalid server nonce");
}
final AuthKey authKey = new AuthKey(gab.toByteArray());
// OK, Retry and Fail have numbers 1, 2 and 3 respectively
final int nonceNumber = 1;
final BigInteger newNonceHash = authKey.calcNewNonceHash(newNonce, nonceNumber);
if (!dhGen.newNonceHash1().equals(newNonceHash)) {
throw new SecurityException("Step 3 DH gen data have invalid nonce hash");
}
return authKey; // TODO And time offset
}
}

96
lib/src/main/java/io/github/lonamiwebs/overgram/utils/AES.java Normal file
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@ -0,0 +1,96 @@
package io.github.lonamiwebs.overgram.utils;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
public class AES {
public static byte[] decryptIge(final byte[] cipherText, final byte[] key, final byte[] iv) {
final Cipher cipher;
try {
cipher = Cipher.getInstance("AES/ECB/NoPadding");
} catch (NoSuchAlgorithmException | NoSuchPaddingException ignored) {
throw new SecurityException("AES/ECB/NoPadding is required but not available");
}
try {
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"));
} catch (InvalidKeyException ignored) {
throw new SecurityException("Invalid key");
}
final int blockSize = cipher.getBlockSize();
final byte[] plainText = new byte[cipherText.length];
byte[] x;
byte[] y;
byte[] xPrev = Arrays.copyOfRange(iv, 0, blockSize);
byte[] yPrev = Arrays.copyOfRange(iv, blockSize, iv.length);
try {
for (int i = 0; i < cipherText.length; ) {
x = Arrays.copyOfRange(cipherText, i, i + blockSize);
y = Utils.xor(cipher.doFinal(Utils.xor(x, yPrev)), xPrev);
xPrev = x;
yPrev = y;
for (int j = 0; j < blockSize; ++j) {
plainText[i] = y[j];
++i;
}
}
} catch (IllegalBlockSizeException | BadPaddingException ignored) {
throw new SecurityException("Illegal block size or padding");
}
return plainText;
}
public static byte[] encryptIge(final byte[] plainText, final byte[] key, final byte[] iv) {
final Cipher cipher;
try {
cipher = Cipher.getInstance("AES/ECB/NoPadding");
} catch (NoSuchAlgorithmException | NoSuchPaddingException ignored) {
throw new SecurityException("AES/ECB/NoPadding is required but not available");
}
try {
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"));
} catch (InvalidKeyException ignored) {
throw new SecurityException("Invalid key");
}
final int blockSize = cipher.getBlockSize();
final byte[] paddedPlain;
if (plainText.length % 16 == 0) {
paddedPlain = plainText;
} else {
paddedPlain = Utils.concat(plainText, Utils.randomBytes(16 - plainText.length % 16));
}
final byte[] cipherText = new byte[paddedPlain.length];
byte[] x;
byte[] y;
byte[] xPrev = Arrays.copyOfRange(iv, 0, blockSize);
byte[] yPrev = Arrays.copyOfRange(iv, blockSize, iv.length);
try {
for (int i = 0; i < paddedPlain.length; ) {
y = Arrays.copyOfRange(paddedPlain, i, i + blockSize);
x = Utils.xor(cipher.doFinal(Utils.xor(y, xPrev)), yPrev);
yPrev = y;
xPrev = x;
for (int j = 0; j < blockSize; ++j) {
cipherText[i] = x[j];
++i;
}
}
} catch (IllegalBlockSizeException | BadPaddingException ignored) {
throw new SecurityException("Illegal block size or padding");
}
return cipherText;
}
}

4
lib/src/main/java/io/github/lonamiwebs/overgram/utils/BinaryReader.java
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@ -125,4 +125,8 @@ public class BinaryReader {
}
return result;
}
public void seek(final int delta) {
buffer.position(buffer.position() + delta);
}
}

33
lib/src/main/java/io/github/lonamiwebs/overgram/utils/Utils.java
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@ -6,6 +6,7 @@ import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;
public class Utils {
@ -44,6 +45,16 @@ public class Utils {
return bytes;
}
public static byte[] concat(final byte[] left, final byte[] right, final int rightLength) {
final byte[] result = Arrays.copyOf(left, left.length + rightLength);
System.arraycopy(right, 0, result, left.length, rightLength);
return result;
}
public static byte[] concat(final byte[] left, final byte[] right) {
return concat(left, right, right.length);
}
public static Pair<BigInteger, BigInteger> factorize(final BigInteger pq) {
final BigInteger two = new BigInteger("2");
@ -110,4 +121,26 @@ public class Utils {
sha1.reset();
return result;
}
public static Pair<byte[], byte[]> generateKeyDataFromNonce(BigInteger serverNonce, BigInteger newNonce) {
final byte[] serverNonceBytes = reversed(serverNonce.toByteArray());
final byte[] newNonceBytes = reversed(newNonce.toByteArray());
final byte[] hash1 = sha1digest(concat(newNonceBytes, serverNonceBytes));
final byte[] hash2 = sha1digest(concat(serverNonceBytes, newNonceBytes));
final byte[] hash3 = sha1digest(concat(newNonceBytes, newNonceBytes));
final byte[] key = concat(hash1, hash2, 12);
final byte[] iv = new byte[8];
System.arraycopy(hash2, 12, iv, 0, 8);
return new Pair<>(key, concat(iv, concat(hash3, newNonceBytes, 4)));
}
public static byte[] xor(final byte[] a, final byte[] b) {
final byte[] result = new byte[Math.min(a.length, b.length)];
for (int i = 0; i < result.length; ++i) {
result[i] = (byte) (0xff & (a[i] ^ b[i]));
}
return result;
}
}