Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python.announce > #2562

ANN: TEXTCOMBINE-SP

Show all headers | View raw

An estimate of entropy of English texts is 1.34 bits per letter [1]. This
implies that, if the letters are coded into 5 bits, one needs to 
appropriately
combine 4 text files in order to obtain bit sequences of full entropy, since
4*1.34 = 5.36 > 5. The method used in our software is to sum (mod 32) 
the coded
values of a-z (mapped to 0-25) as 5 bits of the corresponding letters of 
the
text files.

There are plenty of other schemes for obtaining high quality pseudo-random
sequences in practice, e.g. AES in counter mode. However our scheme seems to
be much simpler both in the underlying logic (understandability) and in
implementation and is thus a viable alternative that one could use/need 
under
circumstances.

The software is available at mok-kong-shen.de

M. K. Shen
------------------------------------------------------------------------

[1] T. M. Cover, R. C. King, A Convergent Gambling Estimate of the 
Entropy of
English, IEEE Trans. Inf. Theory, vol. 24, 1978, pp. 413-421.

Back to comp.lang.python.announce | Previous | Next | Find similar | Unroll thread

Thread

ANN: TEXTCOMBINE-SP Mok-Kong Shen <mok-kong.shen@t-online.de> - 2017-07-09 12:33 +0200

csiph-web