This post describes how to generate a few backup public key hashes to add to your HTTP Public Key Pinning (HPKP) config that might save you from bricking your domain if Let’s Encrypt ever gets untrusted like StartCom did.
If you have a healthy distrust of the X.509 PKI trust model, then you’ve probably heard of HPKP (and probably also HSTS & CAA). Website certificate pinning was a trend first started by google, who hard-coded a pin of their certificates in their Chrome browser. Eventually, google helped build a more standardized pinning method under RFC 7469. And today, it’s supported by Chrome, Firefox, and Opera.
Pinning is a great TOFU improvement to https, but–if misconfigured–you could “brick” your domain–making it so that your client’s browsers will refuse to let them access your site for months or years (interestingly, this has also caused some security experts to think of how HPKP could be abused in ransom-ware). Therefore, it’s a good idea to follow a few HPKP Best Practices.
Michael Altfield
Hi, I’m Michael Altfield. I write articles about opsec, privacy, and devops ➡
This post will describe what hardware to buy & how to configure it so that you have 2 wireless networks in your house: One that seamlessly forces all of the traffic on that network through a VPN–and one that connects to the Internet normally . When finished, the internet activity for any device connected to the first network will be entirely encrypted so that the ISP cannot see which websites are visited*, what software you use, and what information you send & receive on the internet.
* Assuming your config doesn’t leak DNS; see improvements section
Update 2017-08-25: Added “kill switch” firewall rule that prevents LAN traffic from escaping to the ISP unless it passed through the VPN’s vtun0 interface first. Following this change, if the VPN connection is down, the internet will not be accessible (as desired) over the ‘home’ wifi network (without this, the router bypasses the VPN by sending the packets straight to the ISP–giving a false sense of privacy).
As some mega websites deploy APIs that are used nearly ubiquitously on most of the Internet’s websites (I’m looking at you Facebook & Google), I’ve begun to compartmentalize my browsers to “jail” specific website usage to a single, sandboxed browser (profile). This is sometimes referred to as a Site-Specific Browser (SSB).
Besides making sure that your SSB is isolated in that it cannot access your regular browser’s data (a configuration I plan to document in the future), it’s essential to block all network traffic from/to your SSB and all websites, except a whitelist. Unfortunately, getting block-all-then-whitelist functionality in uBlock Origin was annoyingly not documented, so I decided to publish it.
If you want uBlock Origin to block all traffic, add the following line to the textbox in your “My filters” tab of uBlock’s Dashboard.
*.* Michael Altfield
Hi, I’m Michael Altfield. I write articles about opsec, privacy, and devops ➡
This post will describe how to route outgoing traffic in a python script running on TAILS first through Tor, then through a SOCKS proxy created with an ssh tunnel. This is helpful when you want to use the anonymizing capabilities of tor, but you need to access a website that explicitly blocks tor exit nodes (common with sites running CloudFlare on default settings).
Michael Altfield
Hi, I’m Michael Altfield. I write articles about opsec, privacy, and devops ➡
This article describes the correct way to use pycurl over Tor, such that both DNS lookup data and HTTP(S) traffic is sent through Tor’s SOCKS5 proxy.
If you google “pycurl tor”, one of the first results is a stackoverflow post that describes how to configure pycurl using the pycurl.PROXYTYPE_SOCKS5 setting. Indeed, even the tutorial To Russia With Love on the Tor Project’s Official Website describes how to pass pycurl through Tor using the pycurl.PROXYTYPE_SOCKS5 setting.
However, using pycurl.PROXYTYPE_SOCKS5 will leak DNS queries associated with your HTTP requests outside of the Tor network! Instead you should use pycurl.PROXYTYPE_SOCKS5_HOSTNAME.
The –socks5-hostname argument was added to libcurl v7.26.0. The pycurl.PROXYTYPE_SOCKS5_HOSTNAME argument wasn’t added to pycurl until pycurl v7.19.5.1, which (at the time of writing) was less than 2 months ago!
This article will describe how to install pycurl v7.19.5.1 onto the latest version of TAILS at the time of writing, which is TAILS v1.2.3.
Michael Altfield
Hi, I’m Michael Altfield. I write articles about opsec, privacy, and devops ➡
This post attempts to answer the following question: If an evesdropper intercepts a message encrypted with gpg, how much information will they be able to extract from the message without a decryption key?
I will show the unencrypted metadata added to a GPG-encypted message, and I will present commands that can be used to extract this unencrypted metadata.
Michael Altfield
Hi, I’m Michael Altfield. I write articles about opsec, privacy, and devops ➡
Your browser aggrigates a *lot* of data about your computer, and it won’t hesitate to provide all of this data to a nosy web site. In fact, if a website requests a large dataset of your computer’s configuration, concatinates it together, and passes it through a hash function, the resulting hash can be farily unique.
This procedure can be done (and is done) on seperate websites to track users and their activity across multiple websites. If the same procedure [get data, concatenate, hash()] produces the same hash value when done on 2 seperate websites, the website can be fairly certain that you’re the same user. This technique for tracking users is known as Browser Fingerprinting.
Just to get an idea of how effective this is, here’s an excerpt from the above-linked article:
[The EFF] found that, over their study of around 1 million visits to their study website, 83.6% of the browsers seen had a unique fingerprint; among those with Flash or Java enabled, 94.2%. This does not include cookies!
You can test the uniqueness of your browser’s “fingerprint” using this handy EFF tool.
I came back from my “cross-country bicycle trip”:http://1guy2biketrips.michaelaltfield.net to discover I could no longer send signed email because my key expired! I’ve also changed colleges from “SPSU”:http://www.spsu.edu/ to “UCF”:http://www.ucf.edu, and my old college is expiring my email address, so here’s what I need to do:
# Extend my key’s expiration another year # Add new email address to subkey # Save updates to key # Export a new public key
Background Information GPG
“GPG (GNU Privacy Guard)”:http://www.gnupg.org/ (used here) is a popular, cross-platform implementation of “OpenPGP (Pretty Good Privacy)”:http://en.wikipedia.org/wiki/Pretty_Good_Privacy defined in “RFC 4880”:http://tools.ietf.org/html/rfc4880. OpenPGP outlines a standard, open message format for maintaining the “confidentiality”:http://en.wikipedia.org/wiki/Information_security#Confidentiality and “integrity”:http://en.wikipedia.org/wiki/Information_security#Integrity of electronic messages.
Why Subkeys?
“Public Key Cryptography”:http://en.wikipedia.org/wiki/Public-key_cryptography is long, complicated, and well outside the scope of this post. However, one thing I never fully understood was the functional purpose of subkeys. Thankfully, “the GPG documentation”:http://www.gnupg.org/gph/en/manual.html is excellent.
So, there’s 2 major things I want to accomplish by using GPG with my email
# Confidentiality through encryption # Integrity through signatures
The designers of PGP viewed the signature role as indefinitely important while the encryption role as dynamic overtime. Therefore, when we first generate a keypair, 2 keys are created: 1 primary key for . . . → Read More: Extend GPG Key Expiration
Plausibly deniable encryption is a fascinating concept. For example, “TrueCrypt”:http://www.truecrypt.org/ (a FOSS for hard disk encryption) has a wonderful “Hidden Volume”:http://www.truecrypt.org/docs/?s=hidden-volume feature that provides “Plausible Deniability”:http://www.truecrypt.org/docs/?s=plausible-deniability. The concept is: you install 2 OS instances on your computer–1 in a hidden volume. If, for whatever reason, you were forced to reveal your encrypted data, you could give access to decrypt your fake, but seemingly legitimate, OS instance. If done correctly, this could prevent you from forfeiting your sensitive data.
What if you want to encrypt some data to a file, bury it on a thumbdrive somewhere, and make it appear to be just an obscure filetype (possibly corrupted)? I ran across “the answer”:http://old.nabble.com/Is-it-possible-to-decide-what-is-a-gpg-file–td26392408.html when studying for my Secure Computing final.
I haven’t had a chance to research this potential solution, but there seems to exist a project that builds onto the Blowfish cypher to achieve this plausibly deniable encryption: “Blowfish Updated Re-entrant Project (BURP)”:http://www.geodyssey.com/.
Exerpt from “burp.txt”:http://www.geodyssey.com/cryptography/burp.txt
Unlike many similar programs, BURP writes to the output file only the ciphertext (i.e., it writes no “file headers”, password verification data, system, program or content identification strings, etc.). Consequently, such file can not be “provably” identified as ciphertext, as long as the key . . . → Read More: Plausibly Deniable File Encryption
