Re-sharing is going to be a problem, because wmsAuthSign was designed to prevent that.
This is a base64 encoded string.
Decoded it results in this string.
server_time=9/27/2014 7:08:10 AM&hash_value=MS5dzpIyNqtpYDZ+UPQBdQ==&validminutes=80
This is a base64 encoded string too.
Decoded it results in this MD5 hash.
The above MD5 hash is created from:
ip address of the viewer
password stored on the server
Hashing is one-way, so it cannot be decrypted to get the password.