sshkey_sigalg_by_name
if ((sigalg = sshkey_sigalg_by_name(alg)) == NULL)
tmp = match_list(sshkey_sigalg_by_name(cp),
if ((expected_alg = sshkey_sigalg_by_name(requested_alg)) == NULL)
const char *sshkey_sigalg_by_name(const char *);