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4

An Introduction to

Biocryptography

CRYPTOGRAPHY AND BIOCRYPTOGRAPHY

It is very important to further protect the biometric templates—by adding

an extra layer of security to them. This solution is primarily answered by

the science of cryptography—especially that of biocryptography, which

combines both the sciences and technologies of biometrics and cryp-

tography. Therefore, the goal of this chapter is to review the science and

principles of cryptography and how it lends itself to the emerging eld of

biocryptography.

INTRODUCTION TO CRYPTOGRAPHY

Cryptography is a science that dates all the way back to the times of Julius

Caesar. In its simplest terms, the science of cryptography is merely the

scrambling and descrambling of text or written messages between two

individual parties.

These individual parties can also be referred to the sender and the

receiver. It is the former that creates the text or the written message that

needs to be sent, and in turn, it is the latter that receives the text or the

written message and then reads it and appropriately responds.

In normal, everyday communications, we always trust that the indi-

vidual party who is receiving the text or written message will receive it

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accordingly, without any type of problem. Although this mostly happens

in our daily lives, given especially the high-tech world we live in today,

this sometimes does not occur.

When this actually happens, we always assume that the worst has

always occurred. However, what is the worse that could happen? The text

or the written message could be intercepted by a third party and mali-

ciously used. Again, in normal everyday conversations, while we would

normally trust the other party (the receiving party) from keeping the

details of the conversation privileged, there is always a chance that a third

party could be covertly listening in and use that very privileged informa-

tion for purposes of personal gain or exploitation, such as that of identity

theft.

We can also extend this example to electronic communications of all

types. For example, when we hit the send button, what assurances do we

have that the receiving party will get our message or that it will not be

intercepted by a third party? Obviously, we cannot really ensure any type

of safety, especially when it comes to electronic communications, like that

of e-mail, which gets transmitted all over the worldwide networks and

the Internet.

However, the only thing that can be guaranteed is that if any type of

message were to be captured by a third party, it would be rendered use-

less. However, how is this task actually accomplished? It is done by the

scrambling and descrambling of the text or the written message. Much

more specically, the text or the written message is scrambled by the

sending party, and it remains scrambled while it is in transit, until the

receiving party gets the text or the written message.

Message Scrambling and Descrambling

At this point, the text or the written message must be unscrambled for it

to make comprehensible sense for the receiving party. For example, a very

simple example of this is that of I LOVE YOU. The sending party would

scramble this message by rearranging the letters as UYO I VEOL. This

message would then stay in this scrambled format while it is in transit,

until it is received by the receiving party.

They would then descramble it, so it would read again I LOVE YOU.

Thus, if this message were to have been captured by a third party, the

content would be rendered useless and totally undecipherable to the

third party. This, in very simple terms, is the science of cryptography. It

is basically the art of scrambling and, in turn, the descrambling of the