Get specific data from text file

I have common configuration file with lots of strings in it, such as:

Get-Content c:\testfile.txt
[password]=pa$$w0rd 
[user]=Adminstrator
[database]=secretdatabase
[connectionspeed]=123151
[protocolused]=tcp
[server1]=123.123.123.123

I can't yet get the particular data. Say, I want only the password value(in this example it happen to be "pa$$w0rd") that strats right after [password]=.

I tried to play around with patterns and substring and indexof too but can't really get exactly what I want.

How can I get to this?