Introduction
This course is designed to show you some of the more advance codes that you might come along as an Intel Agent. With the use of the Internet, codes can be anywhere. You just have to know where to look.
Binary Numbers
Yes, binary numbers can be a hidden code. This way of coding can give a date, or even a coordinate for an attack. If you are not familiar with binary numbers, do not fret. They are not as complicated as you think. The binary number system is a method of representing numbers in which only the digits 0 and 1 are used. Successive units are powers of 2. Ok what does this mean? Here is an example of a binary number, but with no value:
0 0 0 0 0 0 0 0 = 0
Each one of the columns represents a power of 2. Starting at the equal sign, the column values are 1,2,4,6,8,16, 32, 64, 148. To calculate the decimal value, add the values that have a 1 in the column. The maximum number that can be added is 8 bits or 255. This would be represented by a 1 in all columns:
1 1 1 1 1 1 1 1 = 255
Hexadecimal
We are used to using the standard numbering system in the world today. This system is based on a radix of 10. Hexadecimal is based on a radix of 16. But how can we use numbers to display a 16 radix. Easy, we use a combination of numbers and letters. So what we get is:
1 2 3 4 5 6 7 8 9 A B C D E F
A would be 10, B would be 11, C would be 12…and so on. So in order to understand how this works we need to look at a decimal number, but instead of powers of 10, we need to change it to powers of 16…what does this mean. Currently we look at a number as:
Hundreds Place, Tens place, ones place, (decimal point) Tenths Place, Hundredths Place…
You get the picture. Well now with Hexadecimal we are going to change those places to powers of 16. So if we got:
3FC.3h
Note: It can be a problem knowing if a number is a Hex or a decimal number. In this case it is customary to place an h after the Hex to show that it is a Hex ( ex. 3Ah…you would only work with 3A…the h is just a courtesy identifier).
What you would do is multiply the number by the power of 16 they represent and then add them from right to left…. so it would be (3X162) + (15X161) + (12X160) + (3X16-1) which would be (768) + (240) + (12) + (0.1875) = 1020.1875
As you know computers use the binary number system, but utilizing the Hexadecimal system allows for it to be easier on the eyes of humans. So what exactly is the relationship between the two. Each digit of a hexadecimal number represents exactly four digits of a binary number. This property is due to the fact, that 16 equals 24.
ASCII
ASCII stands for American Standard Code for Information Interchange. It is a standard character set comprised of 128 decimal numbers. This code is a standard code utilized by computers. View a decimal ASCII chart HERE.
You can see how this all can help in Cryptoanalysis. If you can’t, I will explain. Since we have direct relationships between the three styles we can now start with a binary number and get a character for it. Here is an example:
01000001 = 41h this then becomes A.
Now you know the direct relationship between the three formats. Cracking these codes is still not going to be an easy task. But, if you utilize the information in this course, it should make it a lot easier.