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); } public static 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("="); 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; default: throw new InvalidStateException(state); } return null; } }