Caesar cipher – pros and cons -Lorenzo.Grp3.1b

Good points of the Caesar cipher is that it is very simple to use. All a person has to do is to write out his message and then referring to his cipher, rewrite his message again, now encrypted. To give the recipient the key, one can just tell them for example “move back 3″ so ‘c’ would be represented by ‘z’, and ‘d’ would be represented by ‘a’.  No machines or devices are needed to decode it. Only maybe a paper and pen for convenience. This is called a Brute Force Attack.

Bad points are that due to the nature of the cipher, an encrypted text has only 26 possiblities, 25 not including the given text. within 5 minutes, an experienced cryptobreaker could crack the code. Anyone else could crack the code in 10 minutes. With the revolvable cipher, anyone could crack the code in 4-5 minutes. the key could be obtained through trial and error. 

To save time a series of strips could be
prepared. Each with 52 letters, the letters would be in alphabetical order twice over.
The strips would be aligned so that the cuphertext read in one position.
They would then be scanned to reveal the plaintext.

The Frequency of the letters used.

An alternative and quicker way to guessing/trial and error is through observing the frequency of the letters. For example, if a certain letter ‘z’ for example is noticed to be repeated very oftenly, you could start off by guessing that ’z’ represents e, the most commonly used letter. then you can from there subsequently the rest of the letters. 

Lorenzo

 

http://en.wikipedia.org/wiki/Caesar_cipher

http://www.murky.org/blg/the-caesar-shift/

Chris Savarese and Brian Hart, The Caesar Cipher, 1999

F.L. Bauer, Decrypted Secrets, 2nd edition, 2000, Springer

David Kahn, The Codebreakers — The Story of Secret Writing