pki: Add ssh_srv_pki_do_sign_sessionid().

include/libssh/pki.h

@@ -83,6 +83,8 @@ ssh_string ssh_pki_do_sign(ssh_session session, ssh_buffer sigbuf,
 ssh_string ssh_pki_do_sign_agent(ssh_session session,
                                  struct ssh_buffer_struct *buf,
                                  const ssh_key pubkey);
+ssh_string ssh_srv_pki_do_sign_sessionid(ssh_session session,
+                                         const ssh_key privkey);
 
 /* Temporary functions, to be removed after migration to ssh_key */
 ssh_public_key ssh_pki_convert_key_to_publickey(ssh_key key);

include/libssh/pki_priv.h

@@ -59,4 +59,6 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
 /* SSH Signing Functions */
 struct signature_struct *pki_do_sign(const ssh_key privatekey,
                                      const unsigned char *hash);
+ssh_signature pki_do_sign_sessionid(const ssh_key key,
+                                    const unsigned char *hash);
 #endif /* PKI_PRIV_H_ */