int colonPos;
if (plainChallenge != null && (colonPos = plainChallenge.indexOf(COLON)) > -1) {
String userName = plainChallenge.substring(0, colonPos);
char[] password = plainChallenge.substring(colonPos + 1).toCharArray();
IdentityManager idm = securityContext.getIdentityManager();
PasswordCredential credential = new PasswordCredential(password);
try {
final AuthenticationMechanismOutcome result;
Account account = idm.verify(userName, credential);
if (account != null) {
securityContext.authenticationComplete(account, name, false);
result = AuthenticationMechanismOutcome.AUTHENTICATED;
} else {
securityContext.authenticationFailed(MESSAGES.authenticationFailed(userName), name);