I wonder why there is a hash signed by private key in the CSR? It does prove that I have the private key that belongs to the public key in the .csr. But who cares whether I actually do possess the private key? The CA doesn´t need this proof for signing the CSR. It just signs the "Subject" data, some metadata and the public key.

Could you pls describe an Attack that would be possible if there was no signed hash in the CSR request?

Thank you


From the RFC, note 2:

Note 2 - The signature on the certification request prevents an entity from requesting a certificate with another party's public key. Such an attack would give the entity the minor ability to pretend to be the originator of any message signed by the other party. This attack is significant only if the entity does not know the message being signed and the signed part of the message does not identify the signer. The entity would still not be able to decrypt messages intended for the other party, of course.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.