Encrypted images require a passphrase for access; the image contents are secure from anyone who doesn’t know the passphrase. They work on Mac OS X 10.1 and later. Encrypted images are much slower to access than unencrypted images. DropDMG uses Apple’s implementation of the Advanced Encryption Standard (AES-128) algorithm. Encrypted StuffIt archives use Allume’s implementation of the AES-256 algorithm.
Click the Set Passphrase… button to choose the passphrase that you want to use. To make sure that you’ve typed what you meant to type, you must enter the same passphrase twice. DropDMG will tell you whether the two typed passphrases are the same. After choosing a passphrase, you can return to the Set Passphrase dialog at any time to verify that the passphrase is what you think it is.
DropDMG stores the password securely in the system keychain.
A blank image passphrase will cause DropDMG to prompt you to enter a passphrase when the image is created. A blank StuffIt passphrase is the same as not having a passphrase.