English analyst found that the probability of occurrence of the letter P is 13.33% which highest followed by Z with 11.67% and occurrence of letters like C, K, L, N or R is negligible. There is only one problem with it and that is short text created using this technique, a crypto analyst can try different attacks solely based on her knowledge of the English language. Mathematically, we have 26 alphabet permutation which means (26 x 25 x 24 x.2) which is about 4 x 1026 possibilities. Let's say we substitute A with E that doesn't mean that B will be replaced by F. In this technique, we simply substitute any random key for each alphabet letter, that is 'A' can be being replaced with any letters from B to Z and 'B' can be changed to rest of the Alphabets but itself and so on. Predictability of Caesar Cipher was its weakness once any key replacement of a single alphabet is known then, the whole message can we decipher and almost 25 attempts are required to break it. Submitted by Himanshu Bhatt, on September 21, 2018Īs we already discussed what are the Substitution techniques and one of its type Ceasar Cipher? So we are not discussing it here for that please refer to Cryptography: CeasarCipher here: Cryptography: Caesar Cipher and its Python Implementations Types of Substitution Techniques Cryptography | Substitution Techniques: Here, we are going to learn about substitution of Cryptography, its types.
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