Merge pull request #665 from SamWhited/issue71

Add SCRAM-SHA1 support
This commit is contained in:
Daniel Gultsch 2014-11-15 15:34:50 +01:00
commit 4c504dea7a
8 changed files with 722 additions and 374 deletions

View File

@ -17,20 +17,23 @@ public class DigestMd5 extends SaslMechanism {
super(tagWriter, account, rng);
}
@Override
public String getMechanism() {
public static String getMechanism() {
return "DIGEST-MD5";
}
private State state = State.INITIAL;
@Override
public String getResponse(final String challenge) {
public String getResponse(final String challenge) throws AuthenticationException {
switch (state) {
case INITIAL:
state = State.RESPONSE_SENT;
final String encodedResponse;
try {
final String[] challengeParts = new String(Base64.decode(challenge,
Base64.DEFAULT)).split(",");
final Tokenizer tokenizer = new Tokenizer(Base64.decode(challenge, Base64.DEFAULT));
String nonce = "";
for (int i = 0; i < challengeParts.length; ++i) {
String[] parts = challengeParts[i].split("=");
for (final String token : tokenizer) {
final String[] parts = token.split("=");
if (parts[0].equals("nonce")) {
nonce = parts[1].replace("\"", "");
} else if (parts[0].equals("rspauth")) {
@ -45,8 +48,7 @@ public class DigestMd5 extends SaslMechanism {
final byte[] y = md.digest(x.getBytes(Charset.defaultCharset()));
final String cNonce = new BigInteger(100, rng).toString(32);
final byte[] a1 = CryptoHelper.concatenateByteArrays(y,
(":" + nonce + ":" + cNonce).getBytes(Charset
.defaultCharset()));
(":" + nonce + ":" + cNonce).getBytes(Charset.defaultCharset()));
final String a2 = "AUTHENTICATE:" + digestUri;
final String ha1 = CryptoHelper.bytesToHex(md.digest(a1));
final String ha2 = CryptoHelper.bytesToHex(md.digest(a2.getBytes(Charset
@ -64,9 +66,16 @@ public class DigestMd5 extends SaslMechanism {
saslString.getBytes(Charset.defaultCharset()),
Base64.NO_WRAP);
} catch (final NoSuchAlgorithmException e) {
return "";
throw new AuthenticationException(e);
}
return encodedResponse;
case RESPONSE_SENT:
state = State.VALID_SERVER_RESPONSE;
break;
default:
throw new InvalidStateException(state);
}
return null;
}
}

View File

@ -12,13 +12,12 @@ public class Plain extends SaslMechanism {
super(tagWriter, account, null);
}
@Override
public String getMechanism() {
public static String getMechanism() {
return "PLAIN";
}
@Override
public String getStartAuth() {
public String getClientFirstMessage() {
final String sasl = '\u0000' + account.getUsername() + '\u0000' + account.getPassword();
return Base64.encodeToString(sasl.getBytes(Charset.defaultCharset()), Base64.NO_WRAP);
}

View File

@ -11,17 +11,43 @@ public abstract class SaslMechanism {
final protected Account account;
final protected SecureRandom rng;
protected static enum State {
INITIAL,
AUTH_TEXT_SENT,
RESPONSE_SENT,
VALID_SERVER_RESPONSE,
}
public static class AuthenticationException extends Exception {
public AuthenticationException(final String message) {
super(message);
}
public AuthenticationException(final Exception inner) {
super(inner);
}
}
public static class InvalidStateException extends AuthenticationException {
public InvalidStateException(final String message) {
super(message);
}
public InvalidStateException(final State state) {
this("Invalid state: " + state.toString());
}
}
public SaslMechanism(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
this.tagWriter = tagWriter;
this.account = account;
this.rng = rng;
}
public abstract String getMechanism();
public String getStartAuth() {
public String getClientFirstMessage() {
return "";
}
public String getResponse(final String challenge) {
public String getResponse(final String challenge) throws AuthenticationException {
return "";
}
}

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@ -0,0 +1,189 @@
package eu.siacs.conversations.crypto.sasl;
import android.util.Base64;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.digests.SHA1Digest;
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;
public class ScramSha1 extends SaslMechanism {
// TODO: When channel binding (SCRAM-SHA1-PLUS) is supported in future, generalize this to indicate support and/or usage.
final private static String GS2_HEADER = "n,,";
private String clientFirstMessageBare;
private byte[] serverFirstMessage;
final private String clientNonce;
private byte[] serverSignature = null;
private static HMac HMAC;
private static Digest DIGEST;
private static final byte[] CLIENT_KEY_BYTES = "Client Key".getBytes();
private static final byte[] SERVER_KEY_BYTES = "Server Key".getBytes();
static {
DIGEST = new SHA1Digest();
HMAC = new HMac(new SHA1Digest());
}
private State state = State.INITIAL;
public ScramSha1(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
super(tagWriter, account, rng);
// This nonce should be different for each authentication attempt.
clientNonce = new BigInteger(100, this.rng).toString(32);
clientFirstMessageBare = "";
}
public static String getMechanism() {
return "SCRAM-SHA-1";
}
@Override
public String getClientFirstMessage() {
if (clientFirstMessageBare.isEmpty() && state == State.INITIAL) {
clientFirstMessageBare = "n=" + 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:
serverFirstMessage = Base64.decode(challenge, Base64.DEFAULT);
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();
// TODO: In future, cache the clientKey and serverKey and re-use them on re-auth.
final byte[] saltedPassword, clientSignature, serverKey, clientKey;
try {
saltedPassword = hi(CryptoHelper.saslPrep(account.getPassword()).getBytes(),
Base64.decode(salt, Base64.DEFAULT), iterationCount);
serverKey = hmac(saltedPassword, SERVER_KEY_BYTES);
serverSignature = hmac(serverKey, authMessage);
clientKey = hmac(saltedPassword, CLIENT_KEY_BYTES);
final byte[] storedKey = digest(clientKey);
clientSignature = hmac(storedKey, authMessage);
} catch (final InvalidKeyException e) {
throw new AuthenticationException(e);
}
final byte[] clientProof = new byte[clientKey.length];
for (int i = 0; i < clientProof.length; i++) {
clientProof[i] = (byte) (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:
final String clientCalculatedServerFinalMessage = "v=" +
Base64.encodeToString(serverSignature, Base64.NO_WRAP);
if (!clientCalculatedServerFinalMessage.equals(new String(Base64.decode(challenge, Base64.DEFAULT)))) {
throw new AuthenticationException("Server final message does not match calculated final message");
}
state = State.VALID_SERVER_RESPONSE;
return "";
default:
throw new InvalidStateException(state);
}
}
public 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;
}
}

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@ -0,0 +1,76 @@
package eu.siacs.conversations.crypto.sasl;
import android.util.Base64;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* A tokenizer for GS2 header strings
*/
public final class Tokenizer implements Iterator<String>, Iterable<String> {
private final List<String> parts;
private int index;
public Tokenizer(final byte[] challenge) {
final String challengeString = new String(challenge);
parts = new ArrayList<>(Arrays.asList(challengeString.split(",")));
index = 0;
}
/**
* Returns true if there is at least one more element, false otherwise.
*
* @see #next
*/
@Override
public boolean hasNext() {
return parts.size() != index + 1;
}
/**
* Returns the next object and advances the iterator.
*
* @return the next object.
* @throws java.util.NoSuchElementException if there are no more elements.
* @see #hasNext
*/
@Override
public String next() {
if (hasNext()) {
return parts.get(index++);
} else {
throw new NoSuchElementException("No such element. Size is: " + parts.size());
}
}
/**
* Removes the last object returned by {@code next} from the collection.
* This method can only be called once between each call to {@code next}.
*
* @throws UnsupportedOperationException if removing is not supported by the collection being
* iterated.
* @throws IllegalStateException if {@code next} has not been called, or {@code remove} has
* already been called after the last call to {@code next}.
*/
@Override
public void remove() {
if(index <= 0) {
throw new IllegalStateException("You can't delete an element before first next() method call");
}
parts.remove(--index);
}
/**
* Returns an {@link java.util.Iterator} for the elements in this object.
*
* @return An {@code Iterator} instance.
*/
@Override
public Iterator<String> iterator() {
return parts.iterator();
}
}

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@ -1,13 +1,14 @@
package eu.siacs.conversations.utils;
import java.security.SecureRandom;
import java.text.Normalizer;
public class CryptoHelper {
public static final String FILETRANSFER = "?FILETRANSFERv1:";
final protected static char[] hexArray = "0123456789abcdef".toCharArray();
final protected static char[] vowels = "aeiou".toCharArray();
final protected static char[] consonants = "bcdfghjklmnpqrstvwxyz"
.toCharArray();
final protected static char[] consonants = "bcdfghjklmnpqrstvwxyz".toCharArray();
final public static byte[] ONE = new byte[] { 0, 0, 0, 1 };
public static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
@ -51,4 +52,30 @@ public class CryptoHelper {
}
return builder.toString();
}
/**
* Escapes usernames or passwords for SASL.
*/
public static String saslEscape(final String s) {
final StringBuilder sb = new StringBuilder((int) (s.length() * 1.1));
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
switch (c) {
case ',':
sb.append("=2C");
break;
case '=':
sb.append("=3D");
break;
default:
sb.append(c);
break;
}
}
return sb.toString();
}
public static String saslPrep(final String s) {
return saslEscape(Normalizer.normalize(s, Normalizer.Form.NFKC));
}
}

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@ -42,6 +42,7 @@ import eu.siacs.conversations.Config;
import eu.siacs.conversations.crypto.sasl.DigestMd5;
import eu.siacs.conversations.crypto.sasl.Plain;
import eu.siacs.conversations.crypto.sasl.SaslMechanism;
import eu.siacs.conversations.crypto.sasl.ScramSha1;
import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.services.XmppConnectionService;
import eu.siacs.conversations.utils.DNSHelper;
@ -271,6 +272,7 @@ public class XmppConnection implements Runnable {
private void processStream(final Tag currentTag) throws XmlPullParserException,
IOException, NoSuchAlgorithmException {
Tag nextTag = tagReader.readTag();
while ((nextTag != null) && (!nextTag.isEnd("stream"))) {
if (nextTag.isStart("error")) {
processStreamError(nextTag);
@ -281,8 +283,14 @@ public class XmppConnection implements Runnable {
} else if (nextTag.isStart("compressed")) {
switchOverToZLib(nextTag);
} else if (nextTag.isStart("success")) {
final String challenge = tagReader.readElement(nextTag).getContent();
try {
saslMechanism.getResponse(challenge);
} catch (final SaslMechanism.AuthenticationException e) {
disconnect(true);
Log.e(Config.LOGTAG, String.valueOf(e));
}
Log.d(Config.LOGTAG, account.getJid().toBareJid().toString() + ": logged in");
tagReader.readTag();
tagReader.reset();
sendStartStream();
processStream(tagReader.readTag());
@ -295,7 +303,12 @@ public class XmppConnection implements Runnable {
final Element response = new Element("response");
response.setAttribute("xmlns",
"urn:ietf:params:xml:ns:xmpp-sasl");
try {
response.setContent(saslMechanism.getResponse(challenge));
} catch (final SaslMechanism.AuthenticationException e) {
// TODO: Send auth abort tag.
Log.e(Config.LOGTAG, e.toString());
}
tagWriter.writeElement(response);
} else if (nextTag.isStart("enabled")) {
Element enabled = tagReader.readElement(nextTag);
@ -616,13 +629,22 @@ public class XmppConnection implements Runnable {
.findChild("mechanisms"));
final Element auth = new Element("auth");
auth.setAttribute("xmlns", "urn:ietf:params:xml:ns:xmpp-sasl");
if (mechanisms.contains("DIGEST-MD5")) {
if (mechanisms.contains(ScramSha1.getMechanism())) {
saslMechanism = new ScramSha1(tagWriter, account, mXmppConnectionService.getRNG());
Log.d(Config.LOGTAG, "Authenticating with " + ScramSha1.getMechanism());
auth.setAttribute("mechanism", ScramSha1.getMechanism());
} else if (mechanisms.contains(DigestMd5.getMechanism())) {
Log.d(Config.LOGTAG, "Authenticating with " + DigestMd5.getMechanism());
saslMechanism = new DigestMd5(tagWriter, account, mXmppConnectionService.getRNG());
} else if (mechanisms.contains("PLAIN")) {
auth.setAttribute("mechanism", DigestMd5.getMechanism());
} else if (mechanisms.contains(Plain.getMechanism())) {
Log.d(Config.LOGTAG, "Authenticating with " + Plain.getMechanism());
saslMechanism = new Plain(tagWriter, account);
auth.setContent(((Plain)saslMechanism).getStartAuth());
auth.setAttribute("mechanism", Plain.getMechanism());
}
if (!saslMechanism.getClientFirstMessage().isEmpty()) {
auth.setContent(saslMechanism.getClientFirstMessage());
}
auth.setAttribute("mechanism", saslMechanism.getMechanism());
tagWriter.writeElement(auth);
} else if (this.streamFeatures.hasChild("sm", "urn:xmpp:sm:"
+ smVersion)

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@ -117,7 +117,7 @@ public final class Jid {
finaljid = finaljid + dp;
}
// Remove trailling "." before storing the domain part.
// Remove trailing "." before storing the domain part.
if (dp.endsWith(".")) {
try {
domainpart = IDN.toASCII(dp.substring(0, dp.length() - 1), IDN.USE_STD3_ASCII_RULES);