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For those of who you are wondering about what the title is, it is a Caesar’s cipher of 13 also popularly known as rot13. For those of you who are wondering about what caesar cipher and rot13 mean, well, it is like the building blocks for steganography. Ok, don’t kill me yet. This post of mine and probably the next one or two posts will discuss cryptography – “the practise and study of encryption and decryption - encoding data so that it can only be decoded by specific individuals”
(Source: http://www.definethat.com/define/265.htm)

Caesar’s cipher is the most basic form of creating a crypt, which involves substitution of one alphabet by another, moved by a specified number of places. So you can replace a by b, b by c and so on to create a caesar cipher of 1. The title of this post is the word “cryptography” in caesar cipher of 13, also popularly known as rot13 (rot13 is available online at www.rot13.com). Rot13 has this special property that if you apply it twice consecutively, it reveals the original word (there being 26 alphabets in the English language)

I always thought a Caesar cipher is quite secure. However, it is actually very simple to decode. A frequency analysis for english articles reveals that the alphabet “a” occurs 8.2% times, b occurs 1.5% times and so on. If you have a sufficiently large amount of the crypt (probably collected over a period of time), you can conduct frequency analysis and easily decode the script. Also the presence of vowels and words like “a”, “an”, “the”, “and” help break the code faster.

So to reduce the vulnerability of caser cipher, what would be required is that the frequency analysis should not reveal any results – this can be achieved by substituting a given alphabet by not just one but several alphabets. This would mean, “a” could be substitute by “b” at one place, “k” at another and “y” at yet another place. This can be achieved by using something called a “Vvtarer Fdhner”

Will discuss the workings of a Vvtarer Fdhner in the next post!

Ps - this is a repost from an earlier blog, i had started writing and had exactly 2 posts! so please not to expect a follow up post on this!