A full-featured password keeper.

Passerby uses AES encryption to keep passwords secure. It has a full graphical user interface and is entirely open source. Passerby is written completely in Python. Executables are available for Microsoft Windows NT/2000/XP, Mac OS X, and I686 Linux (32 bit).

Downloads Screenshots Project Page Who's the Author?


How much does passerby cost? That's a good question. The right answer is that its free. Also, the code is made available under an open source license (GPL 2.0) for your scrutiny and use. If you like passerby please consider donating. The proceeds from your donation will go towards registering code signing certificates so future users know that the passerby program originates from a trusted source (James Stroud, the author).

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When I travel, I often find myself using someone else's computer but need one of my passwords, account numbers, or account PINs. Keeping my passwords and PINs on a laptop is good, but laptops get lost or left behind or crash at the wrong time. I feel that whatever program I have on my "main" computer should also run on any other computer on which I find myself (or that I may buy in the future). I also want a program that keeps my passwords in a very secure file that itself is seamlessly transportable and readable on whichever computer I happen to be using at that moment--be it a Linux box at work, a Mac at home, the Windows machine at my brother's, or whatever. In essence, I need to have a password program that has versions for any computer and that creates files that don't require cumbersome conversion between different kinds of computers--kind of like Adobe PDF files.

So I wrote passerby for myself and made it available to everyone else for free. It is written in pure Python so it can run on just about any machine you encounter, using the exact same password file for every machine. You just need to download the right installer for the machine you are using. I have personally made installers for all of the major platforms that people use--Mac, Linux, Windows. If you run one of these, just go to the download page.

Accessing Your Passwords Anywhere

I keep my passerby file on my computer at work and put it on a USB stick when I travel. If I happen to need to change the file when I travel, I just save it back to my "main" computer from my USB stick. Another way I use passerby (when I am in a pinch and can't find my USB stick) is I email my passerby document to myself and upload it on the other side. passerby documents are small, so you don't have to worry about your passwords clogging your mail box.

Also, when you decide that your new computer is going to be a Mac instead of a Windows machine like your old one, your password file can be used without any conversion at all. Just grab the right installer from the download page.

Three Letter Extension

The official passerby three letter extension is "pby". So name your documents something like "my_passwords.pby".

Passerby Security

You might be worried about stray copies of your password file being left on various computers or someone snooping files on your hard drive. This is a concern no matter what password keeper you use. But, to safeguard your passwords in the best possible way, passerby uses AES encryption to protect passwords. AES (Advanced Encryption Standard) is a military grade encryption standard certified by the US Government. AES is strong encryption. Real strong. That means, if you pick a good master password to protect your passerby document, it should be safe from even the most capable and well funded adversaries, including major governments, your pesky kid brother, and identity thieves--for a long time.

Of course this relies on your choosing a good password for your passerby file. I strongly recommend visiting this page to learn how to create a good password. If that document is no longer available when you read this, just do an internet search on "picking a good password" and do a little reading before you continue.

Now, with that being said, you should take care to not forget the "master" password to your passerby file. The encryption used by passerby is so strong that I seriously doubt anyone (me, you, the US Government, the late Albert Einstein, or even that snotty IT guy) will be able to recover the contents of a passerby document within the next 30 or so years without your password. If you forget your password, consider the contents of your passerby document gone forever. Disclaimer: By using passerby you acknowledge that you understand this fact.

The AES implementation used in passerby is from the Python Cryptography Toolkit, authored by Andrew Kuchling. This code has been subject to extensive public scrutiny because, like passerby itself, it is an open source project.

AES is specified by the United States National Institutes of Standards in the Federal Information Processing Standards Publication 197 (FIPS-197).

Special Types of Computers

First of all, people who have a special type of computer know they have a special type of computer. If you are running Windows 2000 or Windows XP or Mac OSX, then you don't have a special computer and really don't need to read this section. If you are not sure whether you have a special type of computer, then you probably don't have a special type of computer. But, if you do have a special case, you can get passerby to run on your computer easily, just download the source and run passerby with:


For this route, you will need Python 2.3 or later and Andrew Kuchling's Python Cryptography Toolkit installed for your Python.

Copyright © 2006 James C. Stroud. All rights reserved.
Revised April 17, 2006.

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