Statistics filter: How do I calculate the keyspace size of a password?
August 27, 2011 1:35 AM Subscribe
How do I figure out what the size of this password's keyspace is?
posted by vmrob to Computers & Internet (10 answers total) 2 users marked this as a favorite
I currently work for a large company with an archaic IT infrastructure and am forced to change my password every 90 days. While I don't specifically think that such a policy is unwarranted, I am constantly annoyed by the arbitrary restrictions that are placed on the passwords that they will allow me to use. I'm currently estimating the total number of distinct passwords that are possible in this system to be in the realm of 160 trillion, an astonishingly small keyspace for a modern password.
Help me figure out what the exact size of the keyspace is given the following requirements:
- Must be exactly 8 characters.
- Must contain at least 1 uppercase character
- Must contain at least 1 lowercase character
- Must contain at least 1 number
- Must contain a leading letter (upper or lower)
- May contain up to 2 special characters ($ or # only)
- May not have repeating characters