[pooriaazimi]

> Yes, the keychain is encrypted with your OS X user login password and only unlocked on login

The "login" keychain is encry..... (the rest of your sentence).

You can have many more keychains, and they can have far more sophisticated passphrases. I have an "Internet Identities" keychain (for iCloud, Gmail, Dropbox, VPSs, Github, ...) that has a very long passphrase and is not unlocked at the login, nor it stays open after you enter the password (so, if Safari asks for the password and I enter it, the keychain doesn't just stay "open" for all apps to feast upon).