Hard Core Bits

May 4, 2014

This is all starting to get quite interesting…
I’ve been spending the past day trying to sort in my mind the correct terms and flow of ‘injective-ness’ applying to this ‘one-way-fn’.
It’s been encouraging to have initiated correspondence with a helpful mathematician whom has guided my thoughts towards those ends, thanks Alex.
As the function has ‘trapdoor’ output, it would appear from my reading that it need not necessarily be injective but may perhaps satisfy the requirement for a ‘poly pre-image size’?
Trapdoor functions with poly pre-image size yield cryptosystems… This belies the impression that injectivity of the trapdoor function is a necessary feature to directly build a public key cryptosystem from it, and also suggests that the super-polynomial pre-image size in the construction of Theorem 1 is necessary.” Bellare, Halevi et.al, CRYPTO 98: Many-to-One Trapdoor Functions and Their Relation to Public-Key Cryptosystems. p286-7.
I believe my function to be surjective but inversly injective. Does that == bijective???
So much to learn… one way permutations, cryptographic hash functions, hard core predicates…
That’s not a learning curve, it’s a cliff/overhang.
Someone drop me a line please!


One Response to “Hard Core Bits”

  1. oogenhand Says:

    Reblogged this on oogenhand.


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