How does Mint work?

[Tom Adams]

You give Mint your passwords. If they hash them then they don't have
a (practical) way to reverse the hash, so they will not have the
passwords to retrieve information from your accounts.

So, how do they do it? Do they use reversible encryption?

[unruh]

No. When you submit your password to log on, the program hashes that
password and compares it with the stored hash. Thus, only if your
password entered at logon is the same as the original one, will the
hashes be the same, and will you be allowed access.
(They also increase the size of the password by adding a random "salt"--
a random bunch of characters-- so someone cannot precompute the hashes
of a whole bunch of possible passwords to compare them with the stored
hash.)