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#ActualPromit

Posted 19 April 2013 - 02:51 PM

Having sat through a course and done all the math and derivations for graduate level cryptography, I strongly suggest you learn the basics of cryptographic functions and how to reason about them in a rigorous way. The symmetric stuff isn't that difficult. There are a lot of issues even in the responses here; I don't want to call anybody out in particular but there are way more fundamental issues involved than entropy. Consider something like Bruce Schneier's Applied Cryptography as a good introduction to the field that can be had for cheap.

 

Some basic problems that are notable immediately:

* We don't have a working definition of what constitutes secure.

* Mersenne Twister isn't a cryptographically secure RNG and is thus highly inappropriate for this type of use.

* The mathematical properties of XOR make the multi-pass thing totally ineffective, as mentioned previously. 

* XOR the whole message against some value is guaranteed to return some correct bytes of the message.


#2Promit

Posted 19 April 2013 - 01:01 PM

Having sat through a course and done all the math and derivations for graduate level cryptography, I strongly suggest you learn the basics of cryptographic functions and how to reason about them in a rigorous way. The symmetric stuff isn't that difficult. There are a lot of issues even in the responses here; I don't want to call anybody out in particular but there are way more fundamental issues involved than entropy. Consider something like Bruce Schneier's Applied Cryptography as a good introduction to the field that can be had for cheap.


#1Promit

Posted 19 April 2013 - 01:01 PM

Having sat through a course and done all the math and derivations for graduate level cryptography, I strongly suggest you learn the basics of cryptographic functions and how to reason about them in a rigorous way. The symmetric stuff isn't that difficult. There are a lot of issues even in the responses here; I don't want to call anybody out in particular but there are way more fundamental issues involved than simply entropy. Consider something like Bruce Schneier's Applied Cryptography as a good introduction to the field that can be had for cheap.


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