I have a basic understanding of how blockchain technologies works.
I know that in depends on the ledger where are transactions recorded and can be effectivelly verified.
No one should be able to modify the ledger because of the cryptographic hash functions collisions can't be found so fast with current options.
But from that point of view the security of the blokchain technology or use case depends on how many transacations are done through time.
For example, if I will have root record and then 5 transaction recorded in ledger and no other transaction for 1 year, would theoretically someone be able to change the ledger? Possible attacker will have enough time to find collisions.
Is that right or blockchain technologies are resistant for such scenario?