Courses Home

Overview

  Day One

       The Wild, Wild, Web.

        Unsecured Base of the Internet

        Assume No Security

        Encryption

        Basic Encryption

        Know Who you are talking to

       Rambling Notes

       Day Two - Rambling Notes1

       Day Two - Rambling Notes2

       Reference Material

       Course Evaluation

Encryption

Encryption is the process of using something that only you and your partner know (a Key), and using it to translate your message into something that can not be understood without that knowledge.

Maybe you want to send your friend a letter that is encrypted. You both have to agree to the 'Key' in advance. For example, you might decide that every letter will be replaced with a two-digit code. Spaces are represented with '00', A = '01', B = '02', ..., Y = '25', and Z = '26'.

You letter might simply be '071515040005220514091407'. Someone finding this message would have no idea what it was. It just looks like you wrote down a number. This could be anything. That is not to say that they could not figure it out, as this is a very simple example. However, only you and the person you exchanged the 'Encryption Key' with will know for sure what this is.

Based on the above information, take out a piece of paper, and decode the message.