Using OpenSSL from the command line in Linux, is there some way to examine a key (either public or private) to determine the key size?
openssl rsa -in private.key -text -noout
The top line of the output will display the key size.
Private-Key: (2048 bit)
To view the key size from a certificate:
$ openssl x509 -in public.pem -text -noout | grep "RSA Public Key" RSA Public Key: (2048 bit)
The first (2048) is the bit length of the key:
$ ssh-keygen -lf /etc/ssh/rsa_key.pub 2048 91:1c:ae:17:16:...