TITLE: Can irreversibility of trapdoor functions generally not be proved?
QUESTION [6 upvotes]: The German Wikipedia article on asymmetric cryptography states that asymmetric cryptography is always based on assumptions which can not be proven:
Die Sicherheit aller asymmetrischen Kryptosysteme beruht also immer auf unbewiesenen Annahmen.
translation:
Thus, the security of all asymmetric cryptosystems is always based on unproven assumptions.
I could not find any confirmation for this statement in other sources.

is this statement correct?
or is it wrong, i.e. while there is no proof for the irreversibility of trapdoor functions yet, it can't be ruled out that there may be a proof that e.g. the prime factorization or discrete logarithm are irreversible functions?

I don't have a strong math background, but e.g. a simple module operation is obviously not reversible because the same result can be achieved with different numbers.

5 mod 3 = 2
8 mod 3 = 2

So for modulo, a proof of irreversibility exists.
(Now, afaik, a modulo-operation is a one-way function but not a trapdoor function - and maybe that's a crucial difference for such a statement of is unprovable).
Update:
Some clarification: How I read this statement is that always does not refer only to the current knowledge, but says that asymmetric cryptography with trapdoor functions is and will generally always be based on unproven assumptions (i.e. it is generally not possible to find a trapdoor function and prove it is irreversible).

REPLY [3 votes]: This is due to the fact that the existence of One-Way Functions (OWF) implies that $P \neq NP$. In other words, with contrapositive, if $P = NP$ then OWF doesn't exit. So if we have one you would know it in the news. Therefore, the security of the cryptographic systems is based on unproven results.
There are candidates for OWF functions like;

Multiplication and Factoring
The Rabin function used in Rabin Cryptosystem
Discrete logarithms used in ECC, ElGamal encryption, DHKE
Cryptographically secure hash functions

After extensive research, these are neither proven as an OWF or the reverse.