How to check whether our RSA certificates are 1024 bits and above?

Question

Recently Microsoft pushed that certificate keys should be 1024 bits or above.

Microsoft minimum key length

How can I verify whether a key is 1024 bits or not?

Answer 1

Open the certificate file with Exlorer, go to Details tab, and look for the Public key field. It shows both the algorithm and bit length.

If the algorithm is RSA, bit length must be no less than 1024.

Note that the algorithm might also be ECC, in which case a bit length of 160 bits is sufficient. You don't see them very often though (yet).