Running 10.12.6 Sierra on an Imac , I have connected my external drive to the Imac , I have encrypted it , filled in encrypt/decrypt password .

After a while I right clicked and it states " encrypted "  when I disconnect the drive and reconnect , it shows up on the desktop , but I can double click on it and it opens , no password required .

 

I have decrypted and encrypted again , but still the same outcome , any thoughts ?

What are you using to enable 'encryption'?

Does the encryption routine allow storing the password in the keychain?

 

If using Apple FileVault or DiskUtility:

 

Clicking on “Remember password in keychain” when entering the encryption/decryption password will allow the drive to be mounted on the Mac without entering the password on that Mac, but it will still require a password to be used on another Mac. For maximum security, it’s best to leave that option unchecked.

I never use the password in keychain ,

 

I just do what I have done before when encrypting , just let my mac do it.

 

Is the a way I can check if I am using " keychain "

Open the Mac Keychain: 

Click Finder > Go > Utilities > Keychain Access

 

In Keychain Access, select the Passwords category on the left to review the list of sites and services for which you've saved a password

 

If you wish to remove a saved password: Right-click the entry, then left-click on Delete in the displayed menu

Thanks RC.

I would hazard a guess its storing the password in RAM, probably an Apple feature you dont want, I would also hazard a guess if you restarted the Mac it would ask for password.