No subject

the example only indicates cleartext/unhashed passwords.

in  src/allmydata/frontends, review of sftpd.py and especially auth.py
suggests that hashed passwords can be used.

However, there is no provision for use of PAM, which would eliminate
need for this service to deal with authentication at all.

module  twisted.cred.credentials   has an interface
IPluggableAuthenticationModules   which looks like a candidate.  My
python skills are not particularly good, but I would think that in file
auth.py the following could be used as a start:


class AccountFileChecker:

    implements(checkers.ICredentialsChecker)

    credentialInterfaces = (credentials.IUsernamePassword,
                            credentials.IUsernameHashedPassword,
                            credentials.IPluggableAuthenticationModules)
                            #  see ref #1

    def __init__(self, client, accountfile):
        self.client = client
        self.passwords = {}
        self.pubkeys = {}
        self.rootcaps = {}
        for line in open(os.path.expanduser(accountfile), "r"):
            line = line.strip()
            if line.startswith("#") or not line:
                continue
            name, passwd, rest = line.split(None, 2)
            if passwd in ("ssh-dss", "ssh-rsa"):
                bits = rest.split()
                keystring = " ".join(bits[-1])
                rootcap = bits[-1]
                self.pubkeys[name] = keystring
            elif passwd in ("usepam"):
                # some appropriate code to put rest of
                # account file into rootcap var
            else:
                self.passwords[name] = passwd
                rootcap = rest
            self.rootcaps[name] = rootcap


and ?perhaps? later,
    def _somePamPasswdChecker(self....


Someone who knows this better than I should definitely do the
implemenation.  :|


Refs:

(1)
http://twistedmatrix.com/documents/10.2.0/api/twisted.cred.credentials.html

(2)
http://twistedmatrix.com/documents/10.2.0/api/twisted.cred.credentials.IPluggableAuthenticationModules.html