Can openssl convert SSH public key to a PEM file without private key?

Question

So I've seen many many posts on how to do the conversion with private key; but does anyone one know how I can do this with just only public key? As I'm trying to convert someone else's public key.

Or is this something not possible and I need to ask them to generate one themselves?

Solution

If you are just looking to convert a public key, not create a certificate then you only need the public key.

ssh-keygen -f id_rsa.pub -e -m pem > id_rsa.pub.pem

Will read a public key file id_rsa.pub (containing just your friend's public key) and convert it to pem format.

The private key would be needed for something like a self signed certificate (in x509 format) because it's the private key that generates the signature.

Comments

[Philip Couling]

PEM format can wrap up a few different things. Could you clarify. Are you trying to create a certificate (x509) or are you just trying to convert the public key format?

[Арсений Черенков]

are you trying to get a private key from a public key ? assymetric key were meant to make this impossible. Could you give more details ?

[Praveen Premaratne]

Thank you; this is what I was looking for.