sshkey_xmss_siglen
if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
if ((r = sshkey_xmss_siglen(k, &required_siglen)) != 0)
int sshkey_xmss_siglen(const struct sshkey *, size_t *);