What I need is to get the same result as:
# openssl passwd -1 -salt SaltSalt thesecretpassword
$1$SaltSalt$d4KyTrYpU26ghRyvibVDY0
At least the last part(d4KyTrYpU26ghRyvibVDY0), as the first two parts are fixed to $1$SaltSalt$.
This is needed, so it can be set for a password of a Linux user.
I found it in commons-codec:
Crypt.crypt(password, String.format("$1$SaltSalt", "thesecretpassword"))