There has been quite a bit of recent activity in my 2ze.us project since I first released it nearly a year ago. My intent was not to become a competitor with bit.ly, is.gd, or anyone else in the URL-shortening arena. I created the site as a way for me to learn more about Google's AppEngine. It didn't take very long to get it up and running, and it seemed to work fairly well.

Folks, I cannot take this any longer. I've had Fedora 11 installed on my computer for 5 days now. That is close enough to a week for me. There simply is not enough about Fedora right now to keep me using it. Perhaps the next release will be better for me. I honestly hope so.

To be perfectly honest, I enjoyed most of the Fedora experience these past few days. I was thoroughly impressed with the speed and memory usage in Fedora compared to Jaunty. When I mentioned that on Twitter the other day, one fellow asked if the two systems were running the exact same software. His train of thought seemed to be that you can't really compare two different distros for speed or memory usage unless they run the exact same software at the time of the sample.

My response to that is that it doesn't matter to me in this particular case. I was comparing the general performance of both distros using their "stock" configuration. You can customize a distro however you'd like, and, in the end, that's where you'll probably find the most performance gains in any system.

But performance out of the box is important to me. I'll just leave it at that.

As I write this, I'm creating an ISO of slackware-current (as of midnight MST) so I can see what KDE 4 is like on a real distribution. Heh. This oughta be fun. Anyway, I truly hope that the next release of Fedora will hold my attention for a bit longer.

I suppose I should update everyone out there about what I've been up to lately. It seems strange to me that I post article much less frequently now than I did when I was a full-time university student. You'd think I'd have a whole lot more time to blog about whatever I've been working on. I suppose I do indeed have that time, it's just that I usually like to wait until my projects are "ready" for the public before I write about them.

The biggest reason I haven't posted much of anything lately is a small Twitter client I've been working on. Its purpose is to be a simple, out-of-the-way Twitter client that works equally well on Windows, Linux, and OSX. The application is written in Python and wxPython, and it has been coming along quite well. It works great in Linux (in GNOME and KDE at least), but Windows and OSX have issues with windows stealing focus when I don't want them to. I'm still trying to figure it out--any advice would be greatly appreciated.

Chirpy currently does nothing more than check your Twitter accounts for updates periodically. It notifies you of new updates using blinking buttons (which can be configured to not blink). I think the interface is pretty nice and easy to use, but I am its developer so it's only proper that I think that way.

Anyway, that project has been sucking up a lot of my free time. It's been frustrating as I build it in Linux only to find that Windows and OSX both act stupidly when I go to test it. That frustration inspired me to tinker with a different approach to a Twitter client. I began fooling around with it last night, and I think the idea has turned out to be more useful than Chripy is after a month of development!

I'm calling this new project "Tim", which is short for "Twitter IM". This one also periodically checks your Twitter account(s) for updates (of course). However, Tim will send any Twitter updates to any Jabber-enabled instant messenger client that you are signed into. If you're like me, you have Google Talk open most of the day, so you can just have Twitter updates go straight there! You can also post updates to Twitter using your Jabber instant messenger when Tim is running by simply sending a message back!!

The really neat stuff comes in when you start to consider the commands that I've added to Tim tonight. I've made it possible for you to filter out certain hashtags, follow/unfollow users, and specify from which Twitter account to post updates (when you have multiple accounts enabled). I hate all of those #FollowFriday tweets... they drive me crazy. So all I have to do is type ./filter followfriday and no tweet that contains #FollowFriday will be sent to my Jabber client. I love it.

More commands are on the way. Also on the way is a friendly interface for configuring Tim. Getting it up and running the first time is... a little less than pleasant :) Once you have it configured it seems to work pretty well though.

If you're interested in trying it out, just head on over to the project's page (http://bitbucket.org/codekoala/twitter-im/). Windows users can download an installer from the Downloads tab. I plan on putting up a DMG a little later tonight for OSX users. Linux users can download the .tar.gz file and install the normal Python way :) Enjoy!

Update: The DMG for OSX is a little bigger than I thought it would be, so I won't be hosting it on bitbucket. Instead, you can download it from my server.

Don't forget to read the README !!!

I spent a little bit of time last night and this morning trying to find some examples for AES encryption using Python and PyCrypto. To my surprise, I had quite a difficult time finding an example of how to do it! I posted a message on Twitter asking for any solid examples, but people mostly just responded with things I had seen before--the libraries that do the encryption, not examples for how to use the libraries.

It wasn't long after that when I just decided to tackle the problem myself. My solution ended up being pretty simple (which is probably why there weren't any solid examples for me to find). However, out of respect for those out there who might still be looking for a solid example, here is my solution:

#!/usr/bin/env python

from Crypto.Cipher import AES
import base64
import os

# the block size for the cipher object; must be 16 per FIPS-197
BLOCK_SIZE = 16

# the character used for padding--with a block cipher such as AES, the value
# you encrypt must be a multiple of BLOCK_SIZE in length.  This character is
# used to ensure that your value is always a multiple of BLOCK_SIZE
PADDING = '{'

# one-liner to sufficiently pad the text to be encrypted
pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * PADDING

# one-liners to encrypt/encode and decrypt/decode a string
# encrypt with AES, encode with base64
EncodeAES = lambda c, s: base64.b64encode(c.encrypt(pad(s)))
DecodeAES = lambda c, e: c.decrypt(base64.b64decode(e)).rstrip(PADDING)

# generate a random secret key
secret = os.urandom(BLOCK_SIZE)

# create a cipher object using the random secret
cipher = AES.new(secret)

# encode a string
encoded = EncodeAES(cipher, 'password')
print 'Encrypted string:', encoded

# decode the encoded string
decoded = DecodeAES(cipher, encoded)
print 'Decrypted string:', decoded

Edit: thanks to John and Kaso for their suggestions, though John's didn't seem to work for me (?)

Edit 2015.12.14: thanks to Stephen for pointing out that the block size for AES is always 16, and the key size can be 16, 24, or 32. See FIPS-197 for more details.

If you plan to use this script, you'll need to have PyCrypto installed on your computer. I have had a difficult time finding this for Windows in the past, so I will mirror the installer that I found over here: http://jintoreedwine.wordpress.com/2008/07/20/python-25-and-encryption-pycrypto-under-windows/. I haven't tried it on Mac OS X yet, but it should be fairly simple to install it. Same goes for Linux.

The output of the script should always change with each execution thanks to the random secret key. Here's some sample output:

$ python aes_encryption.py
Encrypted string: aPCQ8v9WzLM/JusrJPS19K8uUA/34Xiu/ZR+arzl1oM=
Decrypted string: password

$ python aes_encryption.py
Encrypted string: F0cp4hMk8RXjcww270leHnigH++yqysIyPy8Em/qEbI=
Decrypted string: password

$ python aes_encryption.py
Encrypted string: 7gH2QCIPOxXVBjTXrMmdgU2l7Iku5Lch5jpG9OScGZw=
Decrypted string: password

$ python aes_encryption.py
Encrypted string: oJUq0/XHdmYgC3ILgFgF6Tpuo8ZhoEHN9wmnuYvV58Y=
Decrypted string: password

If the comments in the script aren't explanatory enough, please comment and ask for clarification. I will offer any that I am capable of, and I invite others to do the same.

I just had a buddy of mine ask me to write a script that would send an e-mail to you whenever you get an "@reply" on Twitter. I've recently been doing some work on a Twitter application, so I feel relatively comfortable with the python-twitter project to access Twitter. It didn't take very long to come up with this script, and it appears to work fine for us (using a cronjob to run the script periodically).

I thought others on the Internets might enjoy the script as well, so here it is!

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
A simple script to check your Twitter account for @replies and send you an email
if it finds any new ones since the last time it checked.  It was developed using
python-twitter 0.5 and Python 2.5.  It has been tested on Linux only, but it
should work fine on other platforms as well.  This script is intended to be
executed by a cron manager or scheduled task manager.

Copyright (c) 2009, Josh VanderLinden
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
- Neither the name of the organization nor the names of its contributors may
be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

import twitter
import ConfigParser
import os
import sys
from datetime import datetime
import smtplib
from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText
from email.Utils import formatdate

# get the user's "home" directory
DIRNAME = os.path.expanduser('~')
CONFIG = os.path.join(DIRNAME, '.twitter_email_replies.conf')
FORMAT = '%a %b %d %H:%M:%S +0000 %Y'
REPLY_TEMPLATE = """%(author)s said: %(text)s
Posted on %(created_at)s
Go to http://twitter.com/home?status=@%(screen_name)s%%20&in_reply_to_status_id=%(id)s&in_reply_to=%(screen_name)s to post a reply
"""

# sections
AUTH = 'credentials'
EXEC = 'exec_info'
EMAIL = 'email_info'

# make the code a bit "cleaner"
O = lambda s: sys.stdout.write(s + '\n')
E = lambda s: sys.stderr.write(s + '\n')
str2dt = lambda s: datetime.strptime(s, FORMAT)

def get_dict(status):
    my_dict = status.AsDict()
    my_dict['screen_name'] = my_dict['user']['screen_name']
    my_dict['author'] = my_dict['user']['name']
    return my_dict

def main():
    O('Reading configuration from %s' % CONFIG)
    parser = ConfigParser.SafeConfigParser()
    config = parser.read(CONFIG)

    # make sure we have the proper sections
    if not parser.has_section(AUTH): parser.add_section(AUTH)
    if not parser.has_section(EMAIL): parser.add_section(EMAIL)
    if not parser.has_section(EXEC): parser.add_section(EXEC)

    try:
        # get some useful settings from the configuration file
        username = parser.get(AUTH, 'username')
        password = parser.get(AUTH, 'password')

        to_address = parser.get(EMAIL, 'to_address')
        from_address = parser.get(EMAIL, 'from_address')
        smtp_server = parser.get(EMAIL, 'smtp_server')
        smtp_user = parser.get(EMAIL, 'smtp_user')
        smtp_pass = parser.get(EMAIL, 'smtp_pass')

        if '' in [username, password, to_address, from_address, smtp_server]:
            raise Exception('Not configured')
    except Exception:
        E('Please configure your credentials and e-mail information in %s!' % CONFIG)

        # create some placeholders in the configuration file to make it easier
        sections = {
            AUTH: ('username', 'password'),
            EMAIL: ('to_address', 'from_address', 'smtp_server', 'smtp_user', 'smtp_pass')
        }

        for section in sections.keys():
            for opt in sections[section]:
                if not parser.has_option(section, opt):
                    parser.set(section, opt, '')
    else:
        # determine the last time we checked for replies
        try:
            last_check = str2dt(parser.get(EXEC, 'last_run'))
        except ConfigParser.NoOptionError:
            last_check = datetime.utcnow()
        last_check_str = last_check.strftime(FORMAT)

        info = 'Fetching updates for %s since %s' % (username,
                                                       last_check_str)
        O(info)

        # attempt to connect to Twitter
        api = twitter.Api(username=username, password=password)

        # not using the `since` parameter for more backward-compatibility
        timeline = api.GetReplies()
        new_replies = []
        for reply in timeline:
            post_time = str2dt(reply.GetCreatedAt())
            if post_time > last_check:
                new_replies.append(reply)

        count = len(new_replies)
        if count:
            # send out an email for this user
            O('Found %i new replies... sending e-mail to %s' % (count, to_address))
            reply_list = '\n\n'.join([REPLY_TEMPLATE % get_dict(r) for r in new_replies])
            is_are = 'is'
            plural = 'y'
            if count != 1:
                is_are = 'are'
                plural = 'ies'

            params = {
                'is_are': is_are,
                'count': count,
                'replies': plural,
                'username': username,
                'reply_list': reply_list,
                'last_check': last_check_str
            }

            text = """There %(is_are)s %(count)i new @repl%(replies)s for %(username)s on Twitter since %(last_check)s:

%(reply_list)s""" % params

            # compose the e-mail
            msg = MIMEMultipart()
            msg['From'] = from_address
            msg['To'] = to_address
            msg['Date'] = formatdate(localtime=True)
            msg['Subject'] = 'New @Replies for %s' % username
            msg.attach(MIMEText(text))

            # try to send the e-mail message out
            email = smtplib.SMTP(smtp_server)
            if smtp_user and smtp_pass:
                email.login(smtp_user, smtp_pass)
            email.sendmail(from_address,
                           to_address,
                           msg.as_string())
            email.close()

        # save the current time so we know where to pick up next time
        parser.set(EXEC, 'last_run', datetime.utcnow().strftime(FORMAT))

    # write the config
    O('Saving settings...')
    out = open(CONFIG, 'wb')
    parser.write(out)
    out.close()

if __name__ == '__main__':
    main()

Feel free to copy this script and modify it to your desires. Also, please comment if you have issues using it.