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  • 18 votes cast
Feb
4
comment Source for examples with broken cryptography
I'm starting to get a sense that the best approach is just to look for papers from IACR.
Jan
18
comment LFSR for small numbers with large periods
Perhaps you should "adjust your response" to answer the question. If you want to vote to close, then vote. Question is not off topic. LFSR is clearly very relevant to cryptography and the question can help others, even if my use of it not be considered cryptography. There is no other forum here that will suit the question better.
Jan
16
comment LFSR for small numbers with large periods
I tried your suggested y=..., but the results have a period of 32, the are not uniformly distributed (many numbers are missing) and some of them repeat one after the other.
Jan
16
comment LFSR for small numbers with large periods
I have taken your suggestion to pick the lower 5 bits of the stream. It contradicts your assertion. The period is 32. I am plotting the histogram (it shows uniform distribution) and also plotting the numbers sequentially and they repeat exactly every 32 samples. Perhaps your notation was incorrect. I would have expected that selecting m <= n bits results in period (2^m)-1 not (2^n)-1.
Jan
16
comment LFSR for small numbers with large periods
Thanks for your comment. I am using Galois construct for the LFSR. The sequence doesn't need to be cryptographically strong.
Jan
16
comment LFSR for small numbers with large periods
No issue with memory. I can store 32 values.
Jan
16
comment LFSR for small numbers with large periods
Let me explain with a shorter one. Lets say I have 2 bit numbers and the sequence goes something like 0 2 1 3 0 2 1 3,... I don't want it to keep doing 0213, i want it to keep changing 0 2 1 3, 2 0 3 1, ...
Jan
16
comment LFSR for small numbers with large periods
@Thomas: Yes exactly. I tried modulus and a few other things, but this resulted in a very short period.
Jan
16
comment LFSR for small numbers with large periods
If I use 5 bits LFSR, the period is very short. Not very desirable.