248 lines
9.1 KiB
Java
248 lines
9.1 KiB
Java
/**
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*
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* Copyright 2014-2019 Florian Schmaus
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smack.sasl.provided;
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import java.nio.charset.StandardCharsets;
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import javax.security.auth.callback.CallbackHandler;
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import org.jivesoftware.smack.SmackException.SmackSaslException;
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import org.jivesoftware.smack.sasl.SASLMechanism;
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import org.jivesoftware.smack.util.ByteUtils;
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import org.jivesoftware.smack.util.MD5;
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import org.jivesoftware.smack.util.StringUtils;
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public class SASLDigestMD5Mechanism extends SASLMechanism {
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public static final String NAME = DIGESTMD5;
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private static final String INITAL_NONCE = "00000001";
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/**
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* The only 'qop' value supported by this implementation
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*/
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private static final String QOP_VALUE = "auth";
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private enum State {
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INITIAL,
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RESPONSE_SENT,
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VALID_SERVER_RESPONSE,
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}
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private static boolean verifyServerResponse = true;
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public static void setVerifyServerResponse(boolean verifyServerResponse) {
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SASLDigestMD5Mechanism.verifyServerResponse = verifyServerResponse;
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}
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/**
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* The state of the this instance of SASL DIGEST-MD5 authentication.
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*/
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private State state = State.INITIAL;
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private String nonce;
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private String cnonce;
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private String digestUri;
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private String hex_hashed_a1;
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@Override
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protected void authenticateInternal(CallbackHandler cbh) {
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throw new UnsupportedOperationException("CallbackHandler not (yet) supported");
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}
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@Override
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protected byte[] getAuthenticationText() {
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// DIGEST-MD5 has no initial response, return null
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return null;
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}
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@Override
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public String getName() {
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return NAME;
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}
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@Override
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public int getPriority() {
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return 210;
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}
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@Override
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public SASLDigestMD5Mechanism newInstance() {
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return new SASLDigestMD5Mechanism();
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}
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@Override
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public boolean authzidSupported() {
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return true;
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}
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@Override
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public void checkIfSuccessfulOrThrow() throws SmackSaslException {
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if (verifyServerResponse && state != State.VALID_SERVER_RESPONSE) {
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throw new SmackSaslException(NAME + " no valid server response");
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}
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}
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@Override
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protected byte[] evaluateChallenge(byte[] challenge) throws SmackSaslException {
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if (challenge.length == 0) {
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throw new SmackSaslException("Initial challenge has zero length");
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}
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String challengeString = new String(challenge, StandardCharsets.UTF_8);
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String[] challengeParts = challengeString.split(",");
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byte[] response = null;
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switch (state) {
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case INITIAL:
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for (String part : challengeParts) {
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String[] keyValue = part.split("=", 2);
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String key = keyValue[0];
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// RFC 2831 § 7.1 about the formatting of the digest-challenge:
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// "The full form is "<n>#<m>element" indicating at least <n> and
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// at most <m> elements, each separated by one or more commas
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// (",") and OPTIONAL linear white space (LWS)."
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// Which means the key value may be preceded by whitespace,
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// which is what we remove: *Only the preceding whitespace*.
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key = key.replaceFirst("^\\s+", "");
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String value = keyValue[1];
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if ("nonce".equals(key)) {
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if (nonce != null) {
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throw new SmackSaslException("Nonce value present multiple times");
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}
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nonce = value.replace("\"", "");
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}
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else if ("qop".equals(key)) {
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value = value.replace("\"", "");
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if (!value.equals("auth")) {
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throw new SmackSaslException("Unsupported qop operation: " + value);
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}
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}
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}
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if (nonce == null) {
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// RFC 2831 2.1.1 about nonce "This directive is required and MUST appear exactly
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// once; if not present, or if multiple instances are present, the client should
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// abort the authentication exchange."
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throw new SmackSaslException("nonce value not present in initial challenge");
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}
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// RFC 2831 2.1.2.1 defines A1, A2, KD and response-value
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byte[] a1FirstPart = MD5.bytes(authenticationId + ':' + serviceName + ':'
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+ password);
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cnonce = StringUtils.randomString(32);
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byte[] a1 = ByteUtils.concat(a1FirstPart, toBytes(':' + nonce + ':' + cnonce));
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digestUri = "xmpp/" + serviceName;
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hex_hashed_a1 = StringUtils.encodeHex(MD5.bytes(a1));
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String responseValue = calcResponse(DigestType.ClientResponse);
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// @formatter:off
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// See RFC 2831 2.1.2 digest-response
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String authzid;
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if (authorizationId == null) {
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authzid = "";
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} else {
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authzid = ",authzid=\"" + authorizationId + '"';
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}
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String saslString = "username=\"" + quoteBackslash(authenticationId) + '"'
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+ authzid
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+ ",realm=\"" + serviceName + '"'
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+ ",nonce=\"" + nonce + '"'
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+ ",cnonce=\"" + cnonce + '"'
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+ ",nc=" + INITAL_NONCE
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+ ",qop=auth"
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+ ",digest-uri=\"" + digestUri + '"'
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+ ",response=" + responseValue
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+ ",charset=utf-8";
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// @formatter:on
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response = toBytes(saslString);
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state = State.RESPONSE_SENT;
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break;
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case RESPONSE_SENT:
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if (verifyServerResponse) {
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String serverResponse = null;
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for (String part : challengeParts) {
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String[] keyValue = part.split("=");
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assert (keyValue.length == 2);
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String key = keyValue[0];
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String value = keyValue[1];
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if ("rspauth".equals(key)) {
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serverResponse = value;
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break;
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}
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}
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if (serverResponse == null) {
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throw new SmackSaslException("No server response received while performing " + NAME
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+ " authentication");
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}
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String expectedServerResponse = calcResponse(DigestType.ServerResponse);
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if (!serverResponse.equals(expectedServerResponse)) {
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throw new SmackSaslException("Invalid server response while performing " + NAME
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+ " authentication");
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}
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}
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state = State.VALID_SERVER_RESPONSE;
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break;
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default:
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throw new IllegalStateException();
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}
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return response;
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}
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private enum DigestType {
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ClientResponse,
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ServerResponse
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}
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private String calcResponse(DigestType digestType) {
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StringBuilder a2 = new StringBuilder();
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if (digestType == DigestType.ClientResponse) {
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a2.append("AUTHENTICATE");
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}
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a2.append(':');
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a2.append(digestUri);
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String hex_hashed_a2 = StringUtils.encodeHex(MD5.bytes(a2.toString()));
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StringBuilder kd_argument = new StringBuilder();
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kd_argument.append(hex_hashed_a1);
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kd_argument.append(':');
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kd_argument.append(nonce);
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kd_argument.append(':');
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kd_argument.append(INITAL_NONCE);
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kd_argument.append(':');
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kd_argument.append(cnonce);
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kd_argument.append(':');
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kd_argument.append(QOP_VALUE);
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kd_argument.append(':');
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kd_argument.append(hex_hashed_a2);
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byte[] kd = MD5.bytes(kd_argument.toString());
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String responseValue = StringUtils.encodeHex(kd);
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return responseValue;
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}
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/**
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* Quote the backslash in the given String. Replaces all occurrences of "\" with "\\".
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* <p>
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* According to RFC 2831 § 7.2 a quoted-string consists either of qdtext or quoted-pair. And since quoted-pair is a
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* backslash followed by a char, every backslash in qdtext must be quoted, since it otherwise would be treated as
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* qdtext.
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* </p>
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*
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* @param string the input string.
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* @return the input string where the every backslash is quoted.
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*/
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public static String quoteBackslash(String string) {
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return string.replace("\\", "\\\\");
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}
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}
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