Score:-2

Can someone please explain RSA-OAEP in plain english mathematically?

ru flag

RSA mathematics: https://youtu.be/4zahvcJ9glg

I understand how RSA works mathematically.

Can someone explain RSA-OAEP in plain english?

Score:6
jp flag

The plain RSA encryption is not IND-CPA secure.

Suppose that you are trying to encrypting some message m. I do not know exactly what you are encrypting, but I have a rough idea of it, i.e. I know that m is one among m1, m2, m3, .... If you use plain RSA encryption, then I can simply take your public key, and encrypt each one of m1, m2, m3 ... by myself, and compare the result to your ciphertext. Then I can trivially recover m. In many applications this is undesirable.

OAEP is a way to obfuscate m non-deterministically, so that even if I know the potential range of m, I still do not recover any information about m more than if it were randomly drawn from that range.

Internally, it is a Feistel network cipher. Read Wikipedia on its construction details.

fgrieu avatar
ng flag
RSA-OAEP additionally guards from [Chosen Ciphertext Attacks](https://en.wikipedia.org/wiki/Chosen-ciphertext_attack) which use information leaking from a decrypting device in order to decipher a ciphertext.
I sit in a Tesla and translated this thread with Ai:

mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.