1package eu.siacs.conversations.crypto.sasl;
 2
 3import java.security.SecureRandom;
 4
 5import eu.siacs.conversations.entities.Account;
 6import eu.siacs.conversations.xml.TagWriter;
 7
 8public abstract class SaslMechanism {
 9
10	final protected TagWriter tagWriter;
11	final protected Account account;
12	final protected SecureRandom rng;
13
14	protected enum State {
15		INITIAL,
16		AUTH_TEXT_SENT,
17		RESPONSE_SENT,
18		VALID_SERVER_RESPONSE,
19	}
20
21	public static class AuthenticationException extends Exception {
22		public AuthenticationException(final String message) {
23			super(message);
24		}
25
26		public AuthenticationException(final Exception inner) {
27			super(inner);
28		}
29	}
30
31	public static class InvalidStateException extends AuthenticationException {
32		public InvalidStateException(final String message) {
33			super(message);
34		}
35
36		public InvalidStateException(final State state) {
37			this("Invalid state: " + state.toString());
38		}
39	}
40
41	public SaslMechanism(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
42		this.tagWriter = tagWriter;
43		this.account = account;
44		this.rng = rng;
45	}
46
47	/**
48	 * The priority is used to pin the authentication mechanism. If authentication fails, it MAY be retried with another
49	 * mechanism of the same priority, but MUST NOT be tried with a mechanism of lower priority (to prevent downgrade
50	 * attacks).
51	 * @return An arbitrary int representing the priority
52	 */
53	public abstract int getPriority();
54
55	public abstract String getMechanism();
56	public String getClientFirstMessage() {
57		return "";
58	}
59	public String getResponse(final String challenge) throws AuthenticationException {
60		return "";
61	}
62}