Merge pull request #2233 from SamWhited/scram-sha-2

Add SCRAM-SHA-2 support
This commit is contained in:
Daniel Gultsch 2017-01-16 13:14:48 +01:00 committed by GitHub
commit ac2eee8e81
4 changed files with 263 additions and 212 deletions

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@ -0,0 +1,228 @@
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 String clientFirstMessageBare;
private final String clientNonce;
private byte[] serverSignature = null;
static HMac HMAC;
static Digest DIGEST;
private static final byte[] CLIENT_KEY_BYTES = "Client Key".getBytes();
private static final byte[] SERVER_KEY_BYTES = "Server Key".getBytes();
private static class KeyPair {
final byte[] clientKey;
final byte[] serverKey;
KeyPair(final byte[] clientKey, final byte[] serverKey) {
this.clientKey = clientKey;
this.serverKey = serverKey;
}
}
static {
CACHE = new LruCache<String, KeyPair>(10) {
protected KeyPair create(final String k) {
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations".
// 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(",", 4);
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 static final LruCache<String, KeyPair> CACHE;
protected State state = State.INITIAL;
ScramMechanism(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 = "";
}
@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 = 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();
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations".
final KeyPair keys = CACHE.get(
CryptoHelper.bytesToHex(account.getJid().toBareJid().toString().getBytes()) + ","
+ CryptoHelper.bytesToHex(account.getPassword().getBytes()) + ","
+ CryptoHelper.bytesToHex(salt.getBytes()) + ","
+ String.valueOf(iterationCount)
);
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 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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@ -1,77 +1,21 @@
package eu.siacs.conversations.crypto.sasl; package eu.siacs.conversations.crypto.sasl;
import android.util.Base64;
import android.util.LruCache;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.digests.SHA1Digest; import org.bouncycastle.crypto.digests.SHA1Digest;
import org.bouncycastle.crypto.macs.HMac; 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 java.security.SecureRandom;
import eu.siacs.conversations.entities.Account; import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.utils.CryptoHelper;
import eu.siacs.conversations.xml.TagWriter; import eu.siacs.conversations.xml.TagWriter;
public class ScramSha1 extends SaslMechanism { public class ScramSha1 extends ScramMechanism {
// 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;
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();
public static class KeyPair {
final public byte[] clientKey;
final public byte[] serverKey;
public KeyPair(final byte[] clientKey, final byte[] serverKey) {
this.clientKey = clientKey;
this.serverKey = serverKey;
}
}
private static final LruCache<String, KeyPair> CACHE;
static { static {
DIGEST = new SHA1Digest(); DIGEST = new SHA1Digest();
HMAC = new HMac(new SHA1Digest()); HMAC = new HMac(new SHA1Digest());
CACHE = new LruCache<String, KeyPair>(10) {
protected KeyPair create(final String k) {
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations".
// 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(",", 4);
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 State state = State.INITIAL;
public ScramSha1(final TagWriter tagWriter, final Account account, final SecureRandom rng) { public ScramSha1(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
super(tagWriter, account, rng); super(tagWriter, account, rng);
// This nonce should be different for each authentication attempt.
clientNonce = new BigInteger(100, this.rng).toString(32);
clientFirstMessageBare = "";
} }
@Override @Override
@ -83,156 +27,4 @@ public class ScramSha1 extends SaslMechanism {
public String getMechanism() { public String getMechanism() {
return "SCRAM-SHA-1"; return "SCRAM-SHA-1";
} }
@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 = 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();
// Map keys are "bytesToHex(JID),bytesToHex(password),bytesToHex(salt),iterations".
final KeyPair keys = CACHE.get(
CryptoHelper.bytesToHex(account.getJid().toBareJid().toString().getBytes()) + ","
+ CryptoHelper.bytesToHex(account.getPassword().getBytes()) + ","
+ CryptoHelper.bytesToHex(salt.getBytes()) + ","
+ String.valueOf(iterationCount)
);
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);
}
}
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 +1,30 @@
package eu.siacs.conversations.crypto.sasl;
import org.bouncycastle.crypto.digests.SHA256Digest;
import org.bouncycastle.crypto.macs.HMac;
import java.security.SecureRandom;
import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.xml.TagWriter;
public class ScramSha256 extends ScramMechanism {
static {
DIGEST = new SHA256Digest();
HMAC = new HMac(new SHA256Digest());
}
public ScramSha256(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
super(tagWriter, account, rng);
}
@Override
public int getPriority() {
return 25;
}
@Override
public String getMechanism() {
return "SCRAM-SHA-256";
}
}

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@ -13,8 +13,6 @@ import android.util.Log;
import android.util.Pair; import android.util.Pair;
import android.util.SparseArray; import android.util.SparseArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.xmlpull.v1.XmlPullParserException; import org.xmlpull.v1.XmlPullParserException;
import java.io.ByteArrayInputStream; import java.io.ByteArrayInputStream;
@ -26,8 +24,8 @@ import java.net.IDN;
import java.net.InetAddress; import java.net.InetAddress;
import java.net.InetSocketAddress; import java.net.InetSocketAddress;
import java.net.Socket; import java.net.Socket;
import java.net.UnknownHostException;
import java.net.URL; import java.net.URL;
import java.net.UnknownHostException;
import java.security.KeyManagementException; import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException; import java.security.NoSuchAlgorithmException;
import java.security.Principal; import java.security.Principal;
@ -61,6 +59,7 @@ import eu.siacs.conversations.crypto.sasl.External;
import eu.siacs.conversations.crypto.sasl.Plain; import eu.siacs.conversations.crypto.sasl.Plain;
import eu.siacs.conversations.crypto.sasl.SaslMechanism; import eu.siacs.conversations.crypto.sasl.SaslMechanism;
import eu.siacs.conversations.crypto.sasl.ScramSha1; import eu.siacs.conversations.crypto.sasl.ScramSha1;
import eu.siacs.conversations.crypto.sasl.ScramSha256;
import eu.siacs.conversations.entities.Account; import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.entities.Message; import eu.siacs.conversations.entities.Message;
import eu.siacs.conversations.entities.ServiceDiscoveryResult; import eu.siacs.conversations.entities.ServiceDiscoveryResult;
@ -855,6 +854,8 @@ public class XmppConnection implements Runnable {
auth.setAttribute("xmlns", "urn:ietf:params:xml:ns:xmpp-sasl"); auth.setAttribute("xmlns", "urn:ietf:params:xml:ns:xmpp-sasl");
if (mechanisms.contains("EXTERNAL") && account.getPrivateKeyAlias() != null) { if (mechanisms.contains("EXTERNAL") && account.getPrivateKeyAlias() != null) {
saslMechanism = new External(tagWriter, account, mXmppConnectionService.getRNG()); saslMechanism = new External(tagWriter, account, mXmppConnectionService.getRNG());
} else if (mechanisms.contains("SCRAM-SHA-256")) {
saslMechanism = new ScramSha256(tagWriter, account, mXmppConnectionService.getRNG());
} else if (mechanisms.contains("SCRAM-SHA-1")) { } else if (mechanisms.contains("SCRAM-SHA-1")) {
saslMechanism = new ScramSha1(tagWriter, account, mXmppConnectionService.getRNG()); saslMechanism = new ScramSha1(tagWriter, account, mXmppConnectionService.getRNG());
} else if (mechanisms.contains("PLAIN")) { } else if (mechanisms.contains("PLAIN")) {