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package de.pixart.messenger.crypto.sasl;
import android.util.Base64;
import java.math.BigInteger;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import de.pixart.messenger.entities.Account;
import de.pixart.messenger.utils.CryptoHelper;
import de.pixart.messenger.xml.TagWriter;
public class DigestMd5 extends SaslMechanism {
public DigestMd5(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
super(tagWriter, account, rng);
}
@Override
public int getPriority() {
return 10;
}
@Override
public String getMechanism() {
return "DIGEST-MD5";
}
private State state = State.INITIAL;
@Override
public String getResponse(final String challenge) throws AuthenticationException {
switch (state) {
case INITIAL:
state = State.RESPONSE_SENT;
final String encodedResponse;
try {
final Tokenizer tokenizer = new Tokenizer(Base64.decode(challenge, Base64.DEFAULT));
String nonce = "";
for (final String token : tokenizer) {
final String[] parts = token.split("=", 2);
if (parts[0].equals("nonce")) {
nonce = parts[1].replace("\"", "");
} else if (parts[0].equals("rspauth")) {
return "";
}
}
final String digestUri = "xmpp/" + account.getServer();
final String nonceCount = "00000001";
final String x = account.getUsername() + ":" + account.getServer() + ":"
+ account.getPassword();
final MessageDigest md = MessageDigest.getInstance("MD5");
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()));
final String a2 = "AUTHENTICATE:" + digestUri;
final String ha1 = CryptoHelper.bytesToHex(md.digest(a1));
final String ha2 = CryptoHelper.bytesToHex(md.digest(a2.getBytes(Charset
.defaultCharset())));
final String kd = ha1 + ":" + nonce + ":" + nonceCount + ":" + cNonce
+ ":auth:" + ha2;
final String response = CryptoHelper.bytesToHex(md.digest(kd.getBytes(Charset
.defaultCharset())));
final String saslString = "username=\"" + account.getUsername()
+ "\",realm=\"" + account.getServer() + "\",nonce=\""
+ nonce + "\",cnonce=\"" + cNonce + "\",nc=" + nonceCount
+ ",qop=auth,digest-uri=\"" + digestUri + "\",response="
+ response + ",charset=utf-8";
encodedResponse = Base64.encodeToString(
saslString.getBytes(Charset.defaultCharset()),
Base64.NO_WRAP);
} catch (final NoSuchAlgorithmException e) {
throw new AuthenticationException(e);
}
return encodedResponse;
case RESPONSE_SENT:
state = State.VALID_SERVER_RESPONSE;
break;
case VALID_SERVER_RESPONSE:
if (challenge == null) {
return null; //everything is fine
}
default:
throw new InvalidStateException(state);
}
return null;
}
}
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