No one has formally “proven” that 3-DES or RSA are “secure”. Given this, what evidence do we have that they are indeed secure?

No one has formally “proven” that 3-DES or RSA are “secure”. Given this, what evidence do we have that they are indeed secure?400 wordsIf IPSec provides security at the network layer, why is it that security mechanisms are still needed at layers above IP?400 words