Skip to main content

Base64 Encoding is NOT Cryptography

I have once again come across an IT department who were/are firmly convinced that the commercial web application that they use is secure and has encrypted user details. What it actually does is Base64 encode the password. This is not encryption and must be treated as plaintext.

So what is Base64 encoding and why do we have it? Well, a large number of popular application layer protocols are ASCII text based, i.e. they transfer plain text over the network. A good example of this is HTTP - the protocol used to transfer HTML (or Web) pages around. Originally, only text pages were sent with markup embedded to style it. However, soon other resources were added to the web including pictures, documents, etc. HTTP is designed to transfer plain ASCII text, so how do you transfer a JPEG photograph? Answer: You convert it into plain ASCII text.

The basic principle of converting a file into text is to use the data to represent an index to the ASCII character, e.g. 'A' is 63, 'B' is 64, 'a' is 97, '8' is 56, etc. So, if the first four bytes of your file are 63, 64, 97 and 56, this can be represented by 'ABa8' without loss. However, ASCII is actually only 7 bits and we usually use 8-bit bytes (because of IBM setting the standard - actually a byte was historically just the number of bits required to store a character). Also, ASCII character 13 is a carriage return, 27 is escape and 8 is backspace. These are non-printable and, worse than that, could corrupt the communications as well as remove other characters. So, we can't just do a straight conversion from bytes to ASCII.

This is where Base64 conversion comes in. We split the file up into 6-bit 'bytes', rather than 8-bit. 6 bits give us 64 possible values. These are then represented by the digits, upper and lowercase letters and a couple of symbols ensuring that they are always printable and don't cause problems. So, the Base64 encoded password is just a 6-bit 'byte' representation of an 8-bit byte password and it is trivial to convert between the two. There is no security in Base64 encoding anything. Perhaps I should repeat that again.

Base64 encoding something is not encrypting it and provides NO SECURITY whatsoever!

I am constantly surprised and disappointed that people think that Base64 encoding something will protect it. I know TLS has its problems, but why aren't all web applications using it?

The little JavaScript tool below will allow you to encode and decode Base64 encoded text to see what it's like and how simple it is. If you find Base64 encoded passwords on your network via sniffing then you can use this to decode them.



Enter Text:


Select Encoding or Decoding:



Encode | Decode

Comments

Popular Posts

You say it's 'Security Best Practice' - prove it!

Over the last few weeks I have had many conversations and even attended presentations where people talk about 'Security Best Practices' and how we should all follow them. However, 'Best Practice' is just another way of saying 'What everyone else does!' OK, so if everyone else does it and it's the right thing to do, you should be able to prove it. The trouble is that nobody ever measures best practice - why would you? If everyone's doing it, it must be right.

Well, I don't agree with this sentiment. Don't get me wrong, many of the so-called best practices are good for most organisations, but blindly following them without thought for your specific business could cause as many problems as you solve. I see best practice like buying an off-the-peg suit - it will fit most people acceptably well if they are a fairly 'normal' size and shape. However, it will never fit as well as a tailored suit and isn't an option for those of us who are ou…

Coventry Building Society Grid Card

Coventry Building Society have recently introduced the Grid Card as a simple form of 2-factor authentication. It replaces memorable words in the login process. Now the idea is that you require something you know (i.e. your password) and something you have (i.e. the Grid Card) to log in - 2 things = 2 factors. For more about authentication see this post.

How does it work? Very simply is the answer. During the log in process, you will be asked to enter the digits at 3 co-ordinates. For example: c3, d2 and j5 would mean that you enter 5, 6 and 3 (this is the example Coventry give). Is this better than a secret word? Yes, is the short answer. How many people will choose a memorable word that someone close to them could guess? Remember, that this isn't a password as such, it is expected to be a word and a word that means something to the user. The problem is that users cannot remember lots of passwords, so remembering two would be difficult. Also, having two passwords isn't really…

Security is a mindset not a technology

I often get asked what I look for when hiring security professionals and my answer is usually that I want the right attitude first and foremost - knowledge is easy to gain and those that just collect pieces of paper should maybe think about gaining experience rather than yet more acronyms. However, it's difficult to get someone to change their mindset, so the right attitude is very important. But what is the right attitude?


Firstly, security professionals differ from developers and IT engineers in their outlook and approach, so shouldn't be lumped in with them, in my opinion. The mindset of a security professional is constantly thinking about what could go wrong (something that tends to spill over into my personal life as well, much to the annoyance of my wife). Contrast this with the mindset of a developer who is being measured on their delivery of new features. Most developers, or IT engineers, are looking at whether what they have delivered satisfies the requirements from t…