234 lines
10 KiB
Java
234 lines
10 KiB
Java
package eu.siacs.conversations.crypto.sasl;
|
|
|
|
import android.annotation.TargetApi;
|
|
import android.os.Build;
|
|
import android.util.Base64;
|
|
import android.util.LruCache;
|
|
|
|
import org.bouncycastle.crypto.Digest;
|
|
import org.bouncycastle.crypto.macs.HMac;
|
|
import org.bouncycastle.crypto.params.KeyParameter;
|
|
|
|
import java.math.BigInteger;
|
|
import java.nio.charset.Charset;
|
|
import java.security.InvalidKeyException;
|
|
import java.security.SecureRandom;
|
|
|
|
import eu.siacs.conversations.entities.Account;
|
|
import eu.siacs.conversations.utils.CryptoHelper;
|
|
import eu.siacs.conversations.xml.TagWriter;
|
|
|
|
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
|
|
abstract class ScramMechanism extends SaslMechanism {
|
|
// TODO: When channel binding (SCRAM-SHA1-PLUS) is supported in future, generalize this to indicate support and/or usage.
|
|
private final static String GS2_HEADER = "n,,";
|
|
private static final byte[] CLIENT_KEY_BYTES = "Client Key".getBytes();
|
|
private static final byte[] SERVER_KEY_BYTES = "Server Key".getBytes();
|
|
private static final LruCache<String, KeyPair> CACHE;
|
|
static HMac HMAC;
|
|
static Digest DIGEST;
|
|
|
|
static {
|
|
CACHE = new LruCache<String, KeyPair>(10) {
|
|
protected KeyPair create(final String k) {
|
|
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations,SASL-Mechanism".
|
|
// Changing any of these values forces a cache miss. `CryptoHelper.bytesToHex()'
|
|
// is applied to prevent commas in the strings breaking things.
|
|
final String[] kparts = k.split(",", 5);
|
|
try {
|
|
final byte[] saltedPassword, serverKey, clientKey;
|
|
saltedPassword = hi(CryptoHelper.hexToString(kparts[1]).getBytes(),
|
|
Base64.decode(CryptoHelper.hexToString(kparts[2]), Base64.DEFAULT), Integer.valueOf(kparts[3]));
|
|
serverKey = hmac(saltedPassword, SERVER_KEY_BYTES);
|
|
clientKey = hmac(saltedPassword, CLIENT_KEY_BYTES);
|
|
|
|
return new KeyPair(clientKey, serverKey);
|
|
} catch (final InvalidKeyException | NumberFormatException e) {
|
|
return null;
|
|
}
|
|
}
|
|
};
|
|
}
|
|
|
|
private final String clientNonce;
|
|
protected State state = State.INITIAL;
|
|
private String clientFirstMessageBare;
|
|
private byte[] serverSignature = null;
|
|
|
|
ScramMechanism(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
|
|
super(tagWriter, account, rng);
|
|
|
|
// This nonce should be different for each authentication attempt.
|
|
clientNonce = CryptoHelper.random(100, rng);
|
|
clientFirstMessageBare = "";
|
|
}
|
|
|
|
private static synchronized byte[] hmac(final byte[] key, final byte[] input)
|
|
throws InvalidKeyException {
|
|
HMAC.init(new KeyParameter(key));
|
|
HMAC.update(input, 0, input.length);
|
|
final byte[] out = new byte[HMAC.getMacSize()];
|
|
HMAC.doFinal(out, 0);
|
|
return out;
|
|
}
|
|
|
|
public static synchronized byte[] digest(byte[] bytes) {
|
|
DIGEST.reset();
|
|
DIGEST.update(bytes, 0, bytes.length);
|
|
final byte[] out = new byte[DIGEST.getDigestSize()];
|
|
DIGEST.doFinal(out, 0);
|
|
return out;
|
|
}
|
|
|
|
/*
|
|
* Hi() is, essentially, PBKDF2 [RFC2898] with HMAC() as the
|
|
* pseudorandom function (PRF) and with dkLen == output length of
|
|
* HMAC() == output length of H().
|
|
*/
|
|
private static synchronized byte[] hi(final byte[] key, final byte[] salt, final int iterations)
|
|
throws InvalidKeyException {
|
|
byte[] u = hmac(key, CryptoHelper.concatenateByteArrays(salt, CryptoHelper.ONE));
|
|
byte[] out = u.clone();
|
|
for (int i = 1; i < iterations; i++) {
|
|
u = hmac(key, u);
|
|
for (int j = 0; j < u.length; j++) {
|
|
out[j] ^= u[j];
|
|
}
|
|
}
|
|
return out;
|
|
}
|
|
|
|
@Override
|
|
public String getClientFirstMessage() {
|
|
if (clientFirstMessageBare.isEmpty() && state == State.INITIAL) {
|
|
clientFirstMessageBare = "n=" + CryptoHelper.saslEscape(CryptoHelper.saslPrep(account.getUsername())) +
|
|
",r=" + this.clientNonce;
|
|
state = State.AUTH_TEXT_SENT;
|
|
}
|
|
return Base64.encodeToString(
|
|
(GS2_HEADER + clientFirstMessageBare).getBytes(Charset.defaultCharset()),
|
|
Base64.NO_WRAP);
|
|
}
|
|
|
|
@Override
|
|
public String getResponse(final String challenge) throws AuthenticationException {
|
|
switch (state) {
|
|
case AUTH_TEXT_SENT:
|
|
if (challenge == null) {
|
|
throw new AuthenticationException("challenge can not be null");
|
|
}
|
|
byte[] serverFirstMessage;
|
|
try {
|
|
serverFirstMessage = Base64.decode(challenge, Base64.DEFAULT);
|
|
} catch (IllegalArgumentException e) {
|
|
throw new AuthenticationException("Unable to decode server challenge", e);
|
|
}
|
|
final Tokenizer tokenizer = new Tokenizer(serverFirstMessage);
|
|
String nonce = "";
|
|
int iterationCount = -1;
|
|
String salt = "";
|
|
for (final String token : tokenizer) {
|
|
if (token.charAt(1) == '=') {
|
|
switch (token.charAt(0)) {
|
|
case 'i':
|
|
try {
|
|
iterationCount = Integer.parseInt(token.substring(2));
|
|
} catch (final NumberFormatException e) {
|
|
throw new AuthenticationException(e);
|
|
}
|
|
break;
|
|
case 's':
|
|
salt = token.substring(2);
|
|
break;
|
|
case 'r':
|
|
nonce = token.substring(2);
|
|
break;
|
|
case 'm':
|
|
/*
|
|
* RFC 5802:
|
|
* m: This attribute is reserved for future extensibility. In this
|
|
* version of SCRAM, its presence in a client or a server message
|
|
* MUST cause authentication failure when the attribute is parsed by
|
|
* the other end.
|
|
*/
|
|
throw new AuthenticationException("Server sent reserved token: `m'");
|
|
}
|
|
}
|
|
}
|
|
|
|
if (iterationCount < 0) {
|
|
throw new AuthenticationException("Server did not send iteration count");
|
|
}
|
|
if (nonce.isEmpty() || !nonce.startsWith(clientNonce)) {
|
|
throw new AuthenticationException("Server nonce does not contain client nonce: " + nonce);
|
|
}
|
|
if (salt.isEmpty()) {
|
|
throw new AuthenticationException("Server sent empty salt");
|
|
}
|
|
|
|
final String clientFinalMessageWithoutProof = "c=" + Base64.encodeToString(
|
|
GS2_HEADER.getBytes(), Base64.NO_WRAP) + ",r=" + nonce;
|
|
final byte[] authMessage = (clientFirstMessageBare + ',' + new String(serverFirstMessage) + ','
|
|
+ clientFinalMessageWithoutProof).getBytes();
|
|
|
|
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations,SASL-Mechanism".
|
|
final KeyPair keys = CACHE.get(
|
|
CryptoHelper.bytesToHex(account.getJid().asBareJid().toString().getBytes()) + ","
|
|
+ CryptoHelper.bytesToHex(account.getPassword().getBytes()) + ","
|
|
+ CryptoHelper.bytesToHex(salt.getBytes()) + ","
|
|
+ String.valueOf(iterationCount) + ","
|
|
+ getMechanism()
|
|
);
|
|
if (keys == null) {
|
|
throw new AuthenticationException("Invalid keys generated");
|
|
}
|
|
final byte[] clientSignature;
|
|
try {
|
|
serverSignature = hmac(keys.serverKey, authMessage);
|
|
final byte[] storedKey = digest(keys.clientKey);
|
|
|
|
clientSignature = hmac(storedKey, authMessage);
|
|
|
|
} catch (final InvalidKeyException e) {
|
|
throw new AuthenticationException(e);
|
|
}
|
|
|
|
final byte[] clientProof = new byte[keys.clientKey.length];
|
|
|
|
for (int i = 0; i < clientProof.length; i++) {
|
|
clientProof[i] = (byte) (keys.clientKey[i] ^ clientSignature[i]);
|
|
}
|
|
|
|
|
|
final String clientFinalMessage = clientFinalMessageWithoutProof + ",p=" +
|
|
Base64.encodeToString(clientProof, Base64.NO_WRAP);
|
|
state = State.RESPONSE_SENT;
|
|
return Base64.encodeToString(clientFinalMessage.getBytes(), Base64.NO_WRAP);
|
|
case RESPONSE_SENT:
|
|
try {
|
|
final String clientCalculatedServerFinalMessage = "v=" +
|
|
Base64.encodeToString(serverSignature, Base64.NO_WRAP);
|
|
if (!clientCalculatedServerFinalMessage.equals(new String(Base64.decode(challenge, Base64.DEFAULT)))) {
|
|
throw new Exception();
|
|
}
|
|
state = State.VALID_SERVER_RESPONSE;
|
|
return "";
|
|
} catch (Exception e) {
|
|
throw new AuthenticationException("Server final message does not match calculated final message");
|
|
}
|
|
default:
|
|
throw new InvalidStateException(state);
|
|
}
|
|
}
|
|
|
|
private static class KeyPair {
|
|
final byte[] clientKey;
|
|
final byte[] serverKey;
|
|
|
|
KeyPair(final byte[] clientKey, final byte[] serverKey) {
|
|
this.clientKey = clientKey;
|
|
this.serverKey = serverKey;
|
|
}
|
|
}
|
|
}
|