Monthly Archives: July 2013

Link

Tor and HTTPS

An excellent description of how Tor and HTTPS can help protect your online privacy and secure your web communications.

Link

Lawmakers of both parties voice doubts about NSA surveillance programs

I’m happy to read the Washington Post story discussing the House committee’s hearing on the NSA’s domestic spying programs.  It’s encouraging that both parties aren’t happy with the programs and that “…there are not enough votes in the House now to renew Section 215 [of the Patriot Act] when the law is revisited.”

Of course the wrong arguments were being made by Stewart Baker, the former NSA general council.  Using fear mongering techniques, Baker talked about the failures of the NSA prior to September 11th (which was an investigation failure and not an intelligence failure) and how the “hyped and distorted press reports orchestrated by Edward Snowden” was out to harm the intelligence agencies.  Baker should have been addressing the civil liberties that are being put at risk and the risks to the First and Fourth Amendments.

Needless to say, I’ll be following these hearings closely.

Secure GnuPG configuration

Someone recently asked what my GPG.conf file looks like since he hadn’t updated his in… years.  Okay, let’s take a look and I’ll try to explain what each setting is and why I feel it is important.  I’m not guaranteeing this as being complete and I welcome input from others.

keyserver-options auto-key-retrieve

This says that if a program needs a public key but it’s not in my keyring that it should automatically reach out to the keyserver (see below) and download it.

use-agent

This says to use the GPG agent. I cannot remember, right now, why this was a good idea. Perhaps it isn’t?

auto-key-locate cert pka ldap hkps://hkps.pool.sks-keyservers.net
keyserver hkps://hkps.pool.sks-keyservers.net
keyserver-options ca-cert-file=/etc/ssl/certs/sks-keyservers.netCA.pem
keyserver-options no-honor-keyserver-url
keyserver-options auto-key-retrieve

Almost the fun stuff there.  This is just setting up the keyserver that I wish to use (note the use of hkps instead of hkp).

default-preference-list AES AES192 AES256 TWOFISH SHA1 SHA224 SHA256 SHA384 SHA512 Uncompressed ZIP ZLIB BZIP2
personal-cipher-preferences AES256 TWOFISH AES192 AES
personal-digest-preferences SHA512 SHA384 SHA256 SHA224
personal-compress-preferences BZIP2 ZLIB ZIP

Okay, the fun stuff. These are all the algorithms that I wish to use. If you setup your GPG key to advertise these then it will make it easier for others to use the most secure algorithms since they will already know what you can do. The first line just lists all the preferences. The second, third, and fourth lines actually provide the preferences in order of them being used. If you’ll note my preferred cipher is AES with a 256-bit key and my preferred hash (digest) is SHA with a 512-bit key.  There are other options available and a quick

gpg --help

should provide what options are available to you. For instance, my current installation says that its supported algorithms are:

Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

I’ve omitted 3DES, MD5, and SHA1 from my preferences due to their weaknesses but I could still use them according to my GnuPG software.

Again, this wasn’t meant to be a strict “thou must do this to be secure” but rather a “this is what I’m doing” sort of thing. I’d appreciate feedback!

Inadvertant data leakage from GnuPG

I was recently introduced to a privacy issue when refreshing your OpenPGP keys using GnuPG.  When refreshing your public key ring using a public key server GnuPG will generally use the OpenPGP HTTP Key Protocol (HKP) to synchronize keys.  The problem is that when you do refresh your keys using HKP everyone that you maintain in your public key ring is sent across the Internet unencrypted.  This can allow anyone monitoring your network traffic to receive a complete list of contacts in which you may hope to use OpenPGP.

The fix is quite simple: in your gpg.conf file make sure that your keyserver entries include hkps:// instead of hkp://.  This will force GnuPG to wrap HKP in SSL to keep the key exchange private.

Happy encrypting!