服务器上面的apache添加了一个gnutls的证书，启动报错：
GnuTLS: Failed to Import Private Key ‘xxx.private.key’: (-207) Base64 unexpected header error.
查找问题原因：
Turns out that what it actually means is not “Base64 decoding error”. What it actually means is “You didn’t remove the pass phrase from the key”.
To do that:
$ cp foo.key foo.key.orig $ openssl rsa -in foo.key.orig --out foo.key