How to plot the distribution of a ciphertext? Is there any plot or visualizing program  that can plot the distribution of a plaintext and then the distribution of the ciphertext after applying a ciphering encryption algorithm? I am interested from stream ciphers
What you are looking for is a histogram plot. 

For example, the distribution of letters in the english language looks like this:



The plot of a ciphertext from a strong cipher should have all bars about the same height (a fairly uniform distribution).