sign

        # OpenSSL::Netscape::SPKI.sign

(from ruby core)
### Implementation from SPKI
---
    spki.sign(key, digest) => spki

---

### Parameters
*   *key* - the private key to be used for signing this instance
*   *digest* - the digest to be used for signing this instance


To sign an SPKI, the private key corresponding to the public key set for
this instance should be used, in addition to a digest algorithm in the
form of an OpenSSL::Digest. The private key should be an instance of
OpenSSL::PKey.