@@ -20,215 +20,214 @@ 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,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(",", 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 = CryptoHelper.random(100,rng);
- 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;
- 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 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;
- }
+ // 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;
+ }
+ }
}