OK, so five is an arbitrary number. Still, it works to illustrate the point that there are different kinds of secrets that warrant different levels of security. Since more security takes more effort on your part and possibly more money, you may want to match the level of security to the value of the information being protected.
Here are the five levels as we see them and the appropriate security measures:
Messages that you would be comfortable sending on a post card or shouting across a crowded room fall into this category.
No security is required because you truly have no secret to protect.
Emails you wouldn’t want posted on the company bulletin board but wouldn’t really cause a problem if they were, are trivial secrets. Party plans, romantic crushes, embarrassing childhood experiences, you may not be inclined to discuss these in polite company but, no real harm would come if they were made public.
Don’t send email about even trivial things like this from your work computer. Every email you send is stored on a mail server somewhere. Email may even be archived for compliance purposes. The mail server your employer provides is theirs and they are within their rights to read all the emails on it.
Never use a shared email account or give anyone access to your email by sharing your passwords. Also don’t send this type of material to anyone who shares accounts or passwords.
Significant implies that possible (but not necessarily probable) harm could come to you or someone else if your email became public. For example, if they find out you are interviewing for a new job, your current employer might treat you differently. Or if your salary information became known it could trigger jealousies or bring you to the attention of marketers and scam artists. Your medical information might also fall into this category.
The measures recommended for level 2 are necessary but not sufficient this this level.
If you must send this type of information electronically, consider using some kind of cipher. When using your own computer, encryption software such as PGP is a good idea. It is a bit of work to set up but easy to use afterwards, particularly if you use something like the Enigmail pluggin for your mail reader. If you are not using your own computer there are (less secure) web based services you can employ. Some are these are listed under the products tab above.
Personal identifying information such as credit card numbers, social security number, and bank account numbers and PINs are in this category. This is stuff people may be actively trying to find with malicious intent. Also high value business deals, attorney-client communications, or anything that might be important to someone else.
Ratting out a corrupt senator to the FBI or other whistle blowing activities that could bring harm to you and your family should be strongly protected.
The measures recommended for levels 2 and 3 are necessary but not sufficient this this level.
Definitely use a strong encryption program to hide the content of your message. Your network connection might be tapped so, make sure your email connection uses SSL or TLS so the email headers that say who the message is going to is also encrypted. Look at the recommendations given under “How to keep a secret”.
You may want to use cryptographic signatures to prevent messages from being altered between you and your correspondent.
Also consider using a special secure email service that will protect your identity and keep copies of your email out of hostile hands. Such services are listed under the products and services tabs above.
Now we are probably talking about crime, politics (a fine distinction) or large sums of money; things people get killed over. This might be a good time to ask yourself, “How did I get here?”
The measures recommended for levels 2, 3 and 4 are just a start. If you are not among “the truly paranoid”, you should be.
Definitely use a strong encryption program to hide the content of your message and use electronic (crypto) signatures to prevent third party alterations. Your network connection is tapped so, make sure your email connection uses SSL or TLS. Even so, try to send your email from some place public. Don’t let go of your laptop if you are using one. Make sure your computer is clean with no spy-ware or keyloggers installed.
The people watching you may have access to high power computers and talented cryptanalyst who will try to break your ciphers. Your first defence is to try to keep the message out of their hands. They may also try to get your secret through the real weak link in the process: people. Remember, you are one of those people.
Depending on what you are up to, traffic analysis is another tactic that may be used against you. Much can be learned by knowing who you talk to and when, even if they don’t know what you are saying.
The five levels described above are used as short hand on other pages when discussing specific strategies, software, and service offerings.
Encrypted versus Anonymous Email
In the five levels discussed above, it was assumed that the secret was in the message. In some cases, the message is meant to be public, it is the messenger that needs to be protected.
If this is your situation, you need anonymous email. This usually comes in the form of a service that will remove header information from an email and relay it to the destination without revealing the sender. These services are also listed under the products tab above. We also offer our own, mixmaster based NoName free anonymous email service.