Yahoo email sign in seal?

[runzwithsizorz]

What is this "sign in seal"? I cannot access my email at yahoo.com any longer unless I create a sign in seal, which includes choosing a color, a picture and a text message. They say this is to prevent phishing...
Anyone know what this is all about and if it is legit? I find this extremely annoying as I now cannot access my email with my usual login/password.