According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?
I think he means the original paper by Satoshi
https://bitcoin.org/bitcoin.pdfHowever I can't find any explicit mentioning of the 51% attack in it.
Hm me neither, that's what I thought he referred to as well.
Under "Calculations" section of bitcoin.pdf
quote:
-"We consider the scenario of an attacker trying to generate an alternate chain faster than the honest
chain. Even if this is accomplished, it does not throw the system open to arbitrary changes, such
as creating value out of thin air or taking money that never belonged to the attacker. Nodes are
not going to accept an invalid transaction as payment, and honest nodes will never accept a block
containing them. An attacker can only try to change one of his own transactions to take back
money he recently spent"
end quote.
To generate an alternate chain faster than the honest chain would mean that the attacker would have 51% or greater control of network. How else would someone generate a chain faster than the main chain?
No that seems to make sense. Doesn't seem to be that big of a deal if this is true, however we can't know if he missed something until someone actually tries and succeeds.