On 12 Sep 2015 the forum software was upgraded to move from storing passwords as a "hash" to a "salted hash".
Since then, users using the old passwords had their passwords upgraded to the new version when they logged in.
As a security precaution, any passwords not upgraded by now have been reset. If this happens to you, then you will have to click on the "Forgot password" link to get a new password:
http://www.gammon.com.au/forum/bbpassword.php?action=forgot
The difference is that, whilst you cannot directly get a plaintext password back from a hashed password, it is possible to run a "dictionary attack" against a dictionary of common passwords, using the hash as a key. If a match is found, then the password is discovered.
The "salted hash" system uses a different "salt" for each person, rendering a pre-built dictionary useless. In addition, the time taken to hash the plaintext password into the hashed one has been considerably increased, meaning that an attempt to try all possible passwords would take a long time.
Since then, users using the old passwords had their passwords upgraded to the new version when they logged in.
As a security precaution, any passwords not upgraded by now have been reset. If this happens to you, then you will have to click on the "Forgot password" link to get a new password:
http://www.gammon.com.au/forum/bbpassword.php?action=forgot
The difference is that, whilst you cannot directly get a plaintext password back from a hashed password, it is possible to run a "dictionary attack" against a dictionary of common passwords, using the hash as a key. If a match is found, then the password is discovered.
The "salted hash" system uses a different "salt" for each person, rendering a pre-built dictionary useless. In addition, the time taken to hash the plaintext password into the hashed one has been considerably increased, meaning that an attempt to try all possible passwords would take a long time.