Random text

from Wikipedia, the free encyclopedia
Example of a random text made of capital letters (here grouped in groups of five)
The cryptologist memorial in front of the Poznan Residential Palace shows random texts made up of digits .

In cryptology in particular, a random text is a text in which all characters (mostly only letters , occasionally also numbers ) appear "as randomly as possible" , i.e. independently of one another and with the same probability . Ideally, strongly encrypted texts , ie “good” ciphertexts , should not be distinguishable from random texts in order to make cryptanalysis and breaking ( deciphering ) more difficult.

Based on the usual 26 capital letters of the Latin alphabet , an ideal random text (large length) contains on average all letters with the same frequency . When using 26 different letters (A to Z), each letter occurs on average with 1/26 or 3.85%. For random texts, the entropy ("disorder") is maximum and is calculated as 4.7 bits / character .

The one-time pad (OTP) used for perfect substitution encryption is based on random texts (made up of letters or numbers).

The honor of the three Polish cryptanalyst Marian Rejewski (1905-1980), Jerzy Różycki (1909-1942) and Henryk Zygalski (1908-1978) as well as their performance at break of the German rotor cipher machine Enigma in Poznan built cryptologists monument shows random texts from Digits.

literature