New subject: generate relay fingerprint without tor given the datadir/keys folder?

3 Feb 2017

      Hi,
given the files within the datadir/keys folder (without the
datadir/fingerprint file), is there an easy way to generate the relay
fingerprint? (using openssl?)
According to the spec [1] the fingerprint is the SHA1 hash of the public
key. (I assume RSA pubkey)
According to the tor man page [2] the RSA public key should be in
keys/secret_id_key.
openssl rsa -in secret_id_key -pubout| ..? |sha1sum
thanks,
nusenu
[1]
...
"fingerprint" fingerprint NL

   [At most once]

   A fingerprint (a HASH_LEN-byte of asn1 encoded public key, encoded in
   hex, with a single space after every 4 characters) for this router's
   identity key. A descriptor is considered invalid (and MUST be
   rejected) if the fingerprint line does not match the public key.

[2]
...
   DataDirectory/keys/secret_id_key
       A relay’s RSA1024 permanent identity key, including private and
       public components. Used to sign router descriptors, and to sign
       other keys.