The default XenServer 7.1.2 encrypt method is SHA512.

We can check the hashing algorithm via /etc/shadow root:$6$aOGJ2EZn$5uSzO4gR2eaQWNPdS456cYx7D2QPjJ/.dovKIy

The above $6 is SHA-512 hashing algorithm, more parameters explanation see the following:

$1 = MD5 hashing algorithm.

$2 =Blowfish Algorithm is in use.

$2a=eksblowfish Algorithm

$5 =SHA-256 Algorithm

$6 =SHA-512 Algorithm