Plaintext can refer to anything which humans can understand and/or relate to. This may be as simple as English sentences, a script, or Java code. If you can make sense of what is written, then it is in plaintext. Ciphertext, or encrypted text, is a series of randomized letters and numbers which humans cannot make any sense of. An encryption algorithm takes in a plaintext message, runs the algorithm on the plaintext, and produces a ciphertext. The ciphertext can be reversed through the process of decryption, to produce the original plaintext. Example: We will encrypt a sentence using Caesar Cipher. The key is 7, which means the letter a becomes h. Plaintext: This is a plaintext. Ciphertext: Aopz pz h wshpualea. The process of converting ciphertext to plain text is called ______.
The process of converting ciphertext to plain text is called decryption. Concept: Cyber Security and Threats Is there an error in this question or solution? As in previous weeks, there is some terminology we need to introduce: View Discussion Improve Article Save Article Like Article View Discussion Improve Article Save Article Like Article There are two primary ways in which a plain text can be modified to obtain cipher text: Substitution Technique and Transposition Technique. 1. Substitution Technique: Types of Substitution Technique:
2. Transposition Technique: Types of Transpositional Techniques: (i) Rail Fence Technique – It uses a simple algorithm:
(ii) Simple Columnar Transposition Technique – It uses a simple algorithm:
Now we can read in any order of columns. Lets read it by 3 -> 2 -> 4 ->1 Cipher text : mkoieicn(iii) Vernam Cipher – It uses a simple algorithm:
Weakness of each technique, In the case of Substitution:
In the case of Transposition: Just as there are characteristic letter frequencies, there are also characteristic patterns of pairs of adjacent letters, called diagrams (groups of 2 letters) and trigrams (groups of 3 letters). The frequency of appearance of letter groups can be used to match up plaintext letters that have been separated in a ciphertext. |