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Dec
15
asked Attack against modular inversion operation using side-channels?
Dec
10
answered Can one use a Cryptographic Accumulator to efficiently store Lamport public keys without the need of a Merkle Tree?
Dec
10
asked Can one use a Cryptographic Accumulator to efficiently store Lamport public keys without the need of a Merkle Tree?
Dec
10
accepted How hard is to invert the function that computes the middle-bits of (x^2)?
Dec
4
comment How hard is to invert the function that computes the middle-bits of (x^2)?
The brute-force attack is obviously a upper bound in the number of computations. It does not help me much to known how much time an attacker will require to invert it.
Dec
2
comment How hard is to invert the function that computes the middle-bits of (x^2)?
Also I'm interested in the number of logic gates it takes to implement the inversion circuit, as compared to the number of logic gates it takes to compute f.
Dec
2
asked How hard is to invert the function that computes the middle-bits of (x^2)?
Nov
15
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
I said clearly in the question that I needed a practical computing difference between F and F^-1, not unfeasibility. Maybe the question does not belong to crypto, then where?
Nov
15
revised Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Adds nothing
Nov
15
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
What about making the word length big enough, like using a T-function of 64 bits in a 64-bit CPU? I think inverting it may take at least k*64 machine instructions, while generating it may take only 3 instructions. E.g. F(x) = x + (x^2 v 5)
Nov
15
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Ok. so shuffling adds nothing.
Nov
14
revised Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Text was misleading. Badly written.
Nov
14
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
If you agree, then I will edit the answer to reflect these ideas.
Nov
14
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Yes. My answer was missing some info. I said "using" a T-function, but I didn't said how. Let T1.. Tn be T-functions. Let S1..Sn be fixed bit-shuffles. Then F=(T1 o S1 o T2 o S2 .... Tn o Sn) should be hard to invert. What do you think?
Nov
14
accepted Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Nov
14
answered Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Nov
11
comment Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
The function is for a special kind of Proof-of-work. Currently I'm using a hash function using the subset of invertible values of the domain. But this is far from perfect.
Nov
7
asked Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Aug
3
awarded  Yearling
Jul
24
accepted Is there any weak message for an ECDSA signature?