[Cryptography] A software for combining text files to obtain high quality pseudo-random sequences in practice

[rcs at xmission.com]

In English, in normal Ascii, the vowels are odd.
With your encoding, vowels are even -- the low bit is 0.
Vowels are pretty common, around 50% of typical text.
This will spoil the statistics of your random bits.

Rich Schroeppel
rcs at xmission.com

---
Quoting mok-kong shen <mok-kong.shen at t-online.de>:
> Shannon did some experiments to determine the entropy in English texts.
> A later
> work done by Cover and King [1] gave an estimate of 1.34 bits per   
> letter. 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, TEXTCOMBINE-SP, 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.
>
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