user.py

#!/usr/bin/python

import random
import hashlib
from string import letters
from google.appengine.ext import db


def users_key(group='default'):
    return db.Key.from_path("users", group)


class User(db.Model):
    name = db.StringProperty(required=True)
    pw_hash = db.StringProperty(required=True)
    email = db.StringProperty()

    @classmethod
    def by_name(cls, name):
        u = User.all().filter('name =', name).get()
        return u

    @classmethod
    def by_id(cls, user_id):
        return User.get_by_id(user_id, parent=users_key())

    @classmethod
    def signup(cls, username, pw, email=None):
        pw_hash = User.make_pw_hash(username, pw)
        user = User(name=username, pw_hash=pw_hash, email=email)

    @classmethod
    def make_salt(cls, length=5):
        return ''.join(random.choice(letters) for x in xrange(length))

    @classmethod
    def make_pw_hash(cls, name, pw, salt=None):
        if not salt:
            salt = User.make_salt()
        h = hashlib.sha256(name + pw + salt).hexdigest()
        return "%s,%s" % (salt, h)

    @classmethod
    def valid_hash(cls, name, pw, h):
        salt = h.split(',')[0]
        return h == User.make_pw_hash(name, pw, salt)