Common Criteria is based on idea of a sound way of evaluating security of an operating system. Common Criteria has evolved over years. Security evaluation criteria goes back to ‘70’s. The first standard for this criteria was published in United States Trusted Computer Systems Evaluation Criteria (TCSEC), “Orange Book.” It was published in 1985 by National Security Agency. Europe came up with similar standards in an effort to create an international standard called Information Technology Security Evaluation and Certification (ITSEC) in 1991. This led to CC Editorial Board (CCEB) which was formed establishing globally recognized standards for security evaluation (dinopolis). Each country has its own organization that enforces and advertises these international standards. In United States, both NSA and National Institute of Standards and Technology meet security and testing needs of Information Technology producers and consumers. They do this through a joint program called National Information Assurance Partnership (NIAP). The responsibilities of these organization are outlined in Computer Security Act of 1987 (epic).

Let us take example of scrambling an egg. First, crack shell, pour contents into a bowl and beat contents vigorously until you achieved needed result - well, a scrambled egg. This action of mixing molecules of egg is encryption. Since molecules are mixed-up, we say egg has achieved a higher state of entropy (state of randomness). To return scrambled egg to its original form (including uncracking shell) is decryption. Impossible?

However, if we substitute word “egg” and replace it with “number”, “molecules” with “digits”, it is POSSIBLE. This, my friend, is exciting world of cryptography (crypto for short). It is a new field dominated by talented mathematicians who uses vocabulary like "non-linear polynomial relations", "overdefined systems of multivariate polynomial equations", "Galois fields", and so forth. These cryptographers uses language that mere mortals like us cannot pretend to understand.

In computer, everything stored are numbers. Your MP3 file is a number. Your text message is a number. Your address book is a longer number. The number 65 represents character "A", 97 for small "a", and so on.

For humans, we recognize numbers with digits from 0 to 9, where else, computer can only recognize 0 or 1. This is binary system which uses bits instead of digits. To convert bits to digits, just simply multiply number of bits by 0.3 to get a good estimation. For example, if you have 256-bits of Indonesian Rupiah (one of lowest currency denomination in world), Bill Gates’ wealth in comparison would be microscopic.