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package eu.siacs.conversations.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 eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.utils.CryptoHelper;
import eu.siacs.conversations.xml.TagWriter;
public class DigestMd5 extends SaslMechanism {
public DigestMd5(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
super(tagWriter, account, rng);
}
@Override
public String getMechanism() {
return "DIGEST-MD5";
}
@Override
public String getResponse(final String challenge) {
final String encodedResponse;
try {
final String[] challengeParts = new String(Base64.decode(challenge,
Base64.DEFAULT)).split(",");
String nonce = "";
for (int i = 0; i < challengeParts.length; ++i) {
String[] parts = challengeParts[i].split("=");
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) {
return "";
}
return encodedResponse;
}
}
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