To encrypt or use a cipher (also spelled cypher) to make your message unreadable with out a password...
Encryption isn't complicated
in theory, in practice it gets more complicated the stronger you want the cipher
However with today's technology you can get by with reading the help file and following the demo that comes with most programs.
But if you want to dig deeper in to the subject you will need to do some research, here is a small primer to wet your research apatite. :)
Here is a nice test for you: ROT13 type in a word then click the "Cypher" button. What this program does is takes each character and replaces it with a character removed 13 places, such as 'a' would be 'n'.
The cypher replaces a letter with another letter or series of letters though out a document. That is if the letter is a then the program will replace it with something else in the entire document.
To arrive at the replacement of a given character you create a string of characters that is turned into an algorithm that tells the program to find the character and replace it with another letter or series of letters.
If the a was replaced with any one of the common alphabet characters then the code would be easy to crack but there are other things going on with the algorithm that makes it harder to crack:
The more bits the algorithm has to work with the more sophisticated the code can be, such as only every x (where x is a number) letter a will be replaced with y (where y is a character), on the next pass the letter a would be replaced every x, series of characters b0e%.
The more sophisticated the algorithm is, it can make one or more passes through the document changing more characters to further confuse the program that is trying to decode the document with out the key.
To date there isn't a point where the algorithm is too complicated to work efficiently, it has been said that a 1024K bit (1 Mega bit) algorithm would take over two months to complete on a document of 500K words (almost an average pdf file today).
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But with newer processors this time to
cipher with large keys will be less than it took with say a Pentium 4 of fes years ago using a 512 bit key.
Short story: When I worked for a major company there were some computers stolen. Two of the computers were executive laptops, these laptops had sensitive data about the future of the company in plans and how to accomplish them. The compromise of these plans cost the company a lot of money.
This prompted upper level management to implement levels of security from the everyday mundane job to the executive computers they would all have some type of encryption installed that would defeat a thief. One way to do this is to
encrypt the complete hard drive (there are some very complex and expensive programs that will do this) and if you didn't use the correct password the first time you didn't get a second chance, in that case you had to call the Tech Support Hot Line and tech would come out with a special disk and reset the password. I had to do at least four a day for over a month before people figured out how to create and use a complex password (a complex password contains numbers, letters, and special characters) it was a rough month.
That program was a 512 bit strength cypher program, most of the computers were Pentium 4. They handled the encryption of the hard drive quite well although when you encrypted the hard drive it
did take a couple of hours to complete.
Now the question comes down to do you want to actually cipher your data?
Consider this: If you cipher your data and forget the password how will you get to your data? I only know of two programs that will crack 512 bit encryption both belong to the US Gov.
You may want to consider this:
The US Gov. is currently considering that the use of this method of
protecting your data may be illegal in the sense that it takes a long period of
time to recover the password for data that is protected by this means. A recent
criminal attack proves this point where the FBI sued Apple for the cypher key to
a cell phone; a Judge denied the FBI's request due to privacy concerns for
other cell phone owners...
You can buy a program that will cipher a file, a directory, or a complete hard drive. If you have a laptop it might be a good idea to
cypher any sensitive data you have to carry while traveling. By encrypting the data you have the assurance that if the laptop is stolen your data may not be compromised unless the thief has access to some very sophisticated tools.
One thing to look for when buying a cypher program is the 'peer-to-peer' certification that insures there are no back doors or hidden algorithms that can be used to either capture the password or open the
cyphered data with out the use of the correct password.
But before you use the built in Windows cypher option you may want to read this!