Tag: encryption

Accessing AWS VPC instances using OpenVPN-NL


  1. Amazon VPC CIDR (the /16 one) – is our example

  2. Ubuntu 14.04 instance launched in a public subnet with EIP attached

  3. EIP of the above machine – is our example
  4. SSH connection to the Ubuntu instance

Setting up the server

We are going to use a distribution of OpenVPN called OpenVPN-NL (http://openvpn.fox-it.com/) because it has more secure defaults than the standard OpenVPN installation that is distributed with Ubuntu. Also, OpenVPN-NL makes use of mbed-TLS (previously PolarSSL) instead of OpenSSL because of its compactness and ease of auditability (is that even a word?). Run all following commands as the root user: (more…)


Disk encryption using cryptsetup

Disk encryption is used to encrypt the entire hard disk or a thumb drive in order to secure and protect the information contained within from prying eyes. For this exercise, we shall be using the program called cryptsetup to encrypt a thumb drive.

Obligatory unrelated vintage photo
Obligatory unrelated vintage photo

These instructions can also be extended to hard-disks for full-disk encryption.

Using GPG to password-encrypt files

In addition to public key encryption, GPG can also be used to password encrypt files. This doesn’t use public/private key encryption but uses symmetric key ciphers like AES or CAST.  This can be useful when you simply need to use a shared secret to encrypt or decrypt a file or if you are encrypting a file to yourself for safekeeping.

Wikimedia Commons
Enigma Machine – Flickr Simon Claessen CC-BY

OpenSSL is cool and all but don’t use it to encrypt information in-situ. It’s a bad idea. OpenSSL is good for generating TLS certificates. It wasn’t intended for file encryption.

To encrypt a file named message.txt:


Electronic Mail Encryption

Electronic mails need to be encrypted if you need true privacy when communicating. Encryption is the most practical and effective way of fighting surveillance and privacy violations by the state or any malicious actors like intelligence agencies (unwarranted eavesdropping) and black-hat crackers.

Electronic Mail Encryption can be done using the open implementation of Pretty Good Privacy (PGP, written by Phil Zimmermann) called GNU Privacy Guard (GPG) authored by Werner Koch and others.


Creating a public key pair:

A public key pair is a pair of keys: A public key and a private key. As the name makes it obvious, you keep the private key to yourself and give out the public key. You can create a key pair like so:

Password Security – Primer

Passwords have always been one of the weakest links in information security. Good passwords are hard to generate and remember. Added to that it’s not good practice to use the same password for multiple sites. So one has to use completely random, reasonably long, password that contains upper and lowercase letters, numbers and special characters (phew). As if all this is not enough, several sites – like those of financial institutions – require you to change your password regularly.

All this can make it very difficult to generate, remember and maintain passwords and store passwords in a secure fashion. In this article, let’s tackle the problems with passwords one after the other.

Hopefully, I’ll cover everything that needs to be covered. If I’ve left off something, kindly point it out and I’ll edit the article to fix it as quickly as possible