Thursday, June 17, 2010 , Posted by Shan Serilo at 9:27 AM
The basic of all ciphers is called Caesar Cipher. Why? Well as he roamed far and wide across his vast empire in the past, he needed a way to make sure that if any of his messages were to fall into the enemy hands, his secret plans would remain safe. He uses this way of coding messages so that's why it was named after him.
The Caesar Cipher shifts the alphabet 3 places. So for example A becomes D, B becomes E, C becomes F and so on. So if you were to write "Meet me at the canteen" you would write it as "Phhw ph dw wkh fdqwhhq" To decipher just shift the alphabet 3 letters to the left. Cool?
Now decipher this one =)
"Oryh lv doo wkhuh lv"
So now what would it be like, you may wonder, if we were able to shift the alphabet as many places as we want? It is actually called St. Cyr. Slide. Why it is called that? I don't know, so don't ask me haha. Anyway for example if we shift the alphabet to 10 shifts, A would become K, B would become L, and Z will be J. So if we cipher "University of Santo Tomas" we would write this as "Exsfobcsdi yp Ckxdy Dywkc".
Now decipher this. This is for 10 shifts. =)
"Nkxmobc kbo dro woccoxqobc yp Qyn"
Now let our imagination run wild would we? How about a keyboard cipher? Yes a keyboard, the one that you've been using now in typing. With the combination of St. Cyr. Slide and the Keyboard we could also cipher. How? Let's say that we shift the keyboard letters to 1 letter space to right, so that L would become A, T would become Y, M would become Z and so on. So then if we would cipher "Madrigal" we would right it as "Zlftohsa". There are many other variations to this , you could shift it to left, up, down, right, just let your receiver know how to decipher it or else he wouldn't know how to crack it.
Now decipher this. This only shifts one keyboard letter to the right.
Now this is my favorite. It is called the Date Shift Cipher. You usually uses key to be able to decipher the coded message and that key would be a date. It would be hard to break unless they know the date key. So let's say that we cipher "Dr. Jose Protasio Mercado y Alonso Realonda Rizal". A very long name indeed. We then use his birth date as a key which is June 19, 1861 so that's 06191861. Under the word we would cipher which is Jose Rizal's name we should write our six digit number over and over until we come to an end. So "Dr. Jose Protasio Mercado Y Alonso Realonda Rizal" would be "06. 1918 61061918 6106191 8 610619 18610619 18610". Okay then now shift each letter of the plain text by the number of spaces indicated by the number below it. So the word Dr. would be Dx., Jose would be Kxtm, and Rizal would be Sqfbl. So if we cipher "Dr. Jose Protasio Mercado Y Alonso Realonda Rizal" we would write it as "Dx. Kxtm Vsozbbjw Sfribmp G Gmottx Smgmotej Sqfbl"
To decipher it, you need to know the date key and do the steps all over again but instead of shifting to right, you need to shift it to the left.
Now decipher the name of one of my friends. The key is June 17, 2010
"Jacpnef Mhesy Zhjeh Sbjctbnggz"