A recent and depressing article on ArsTechnica details how easily and quickly crackers can break even quite lengthy and obscure passwords.
We asked three cracking experts to attack the same list Anderson targeted and recount the results in all their color and technical detail Iron Chef style. The results, to say the least, were eye opening because they show how quickly even long passwords with letters, numbers, and symbols can be discovered.
The list contained 16,449 passwords converted into hashes using the MD5 cryptographic hash function. Security-conscious websites never store passwords in plaintext. Instead, they work only with these so-called one-way hashes, which are incapable of being mathematically converted back into the letters, numbers, and symbols originally chosen by the user. In the event of a security breach that exposes the password data, an attacker still must painstakingly guess the plaintext for each hash—for instance, they must guess that “5f4dcc3b5aa765d61d8327deb882cf99” and “7c6a180b36896a0a8c02787eeafb0e4c” are the MD5 hashes for “password” and “password1” respectively. (For more details on password hashing, see the earlier Ars feature “Why passwords have never been weaker—and crackers have never been stronger.”)
…The list of “plains,” as many crackers refer to deciphered hashes, contains the usual list of commonly used passcodes that are found in virtually every breach involving consumer websites. “123456,” “1234567,” and “password” are there, as is “letmein,” “Destiny21,” and “pizzapizza.” Passwords of this ilk are hopelessly weak. Despite the additional tweaking, “[email protected]$$word,” “123456789j,” “letmein1!,” and “LETMEin3” are equally awful. But sprinkled among the overused and easily cracked passcodes in the leaked list are some that many readers might assume are relatively secure. “:LOL1313le” is in there, as are “Coneyisland9/,” “momof3g8kids,” “1368555av,” “n3xtb1gth1ng,” “qeadzcwrsfxv1331,” “m27bufford,” “J21.redskin,” “Garrett1993*,” and “Oscar+emmy2.”
This article is mostly about a higher level of password cracking; basically how encrypted password files are broken, but it does underline and illustrate just how fragile is the security provided by your 8 or 10 letter string, especially if much/most of it is composed of real words, rather than (Lethe-inducing) alphanumeric gibberish. Hence the necessity of second level security measures, such as authenticators.
As a Blue would tell you, Blizzard sells authenticators at cost, and offers mobile authentication for free via cell phone text messaging. You’ve really got no excuse not to use one of these, given the real world value of your Diablo 3 items.