Check your RSA private and public keys

In this post we will see how we can check for errors our RSA private and public keys.

As it mentioned here, we can use the OpenSSL command line utility to generate a private RSA key, and then its public key.

Generate private RSA key

openssl genrsa -out private.key 4096

Generate public RSA key from private

openssl rsa -in private.key -outform PEM -pubout -out public.pem

There are cases of course where the keys are given to us and we spend time to make our code work with them. With the commands below, we can quickly check their validity.

Check private RSA keys for errors

openssl rsa -check -in private.key -noout

The above command will echo just a RSA key ok message if the key is valid. If not, it will list some errors.

Note: The RSA key ok message might appear even if the output has errors. The fact that it shows errors, indicates that the key is not valid.

Check public RSA keys for errors

openssl pkey -inform PEM -pubin -in public.pem -noout

The above command will echo nothing if the key is valid. If not, it will list some errors.

Additional resources

One useful tool to check and manage keys is KeyStore Explorer. It has some cool features such as analyze your keys or detect the file.