How to mount a disk image with automator or Applescript and without hdiutil?

Question

An Automator workflow that mounts a disk image on when I drag and drop the dmg file onto it is easy:

Instead of dragging and dropping the dmg file I want to double click the created workflow and have it mount a specific file. I've tried using "Set Value of Variable" to the path of the dmg, "Open Finder Items", and "Get Selected Folder Items", nothing works.

I can do it with the command line as:

hdiutil mount disk_image_name.dmg

I've also tried with the Applescript:

    on run {input, parameters}

        tell application "DiskImageMounter"
            open "path/disk_image_name.dmg"
        end tell
    end run

But after mounting the disk image as expected, Automator freezes for about 15 seconds and gives the below Syntax Error.

The reason I want to avoid using hdituil is the disk images are encrypted. When using the Automator mount tool the password is done in Apple's dialog box. Using hdiutil I end up passing the password as stdin.

printf '%s\0' "$PASSPHRASE" | hdiutil attach $LOCATION -stdinpass 

Answer 1

I would use hdiutil ... instead of other methods but with an image protected by a certificate instead of a password. This is similar as to building an encrypted image with a password and a recovery key (based on a cert) - without password though:

1. Create a temporary cert folder and cd into it:

   mkdir ~/certsecdmg
   cd ~/certsecdmg 
   

2. Create a root CA if you don't have one already:

   openssl genrsa -des3 -out casecdmg.key 4096
   openssl req -new -x509 -days 7300 -key casecdmg.key -out casecdmg.crt
   

   Fill in all proposed fields.

3. Create a password protected certificate signing request:

   openssl genrsa -des3 -out secdmgbuild.key 4096 
   openssl req -new -key secdmgbuild.key -out secdmgbuild.csr
   

   Fill in all proposed fields.

4. Create the signed certificate in PEM format

   openssl x509 -req -days 7300 -in secdmgbuild.csr -CA casecdmg.crt -CAkey casecdmg.key -set_serial 01 -out secdmgbuild.crt
   

5. Convert the signed certificate to DER format

   openssl x509 -in secdmgbuild.crt -inform pem -out secdmgbuild.der -outform der   
   

6. Bundle the PEM certificate and private key into a PKCS#12 package

   openssl pkcs12 -export -in secdmgbuild.crt -inkey secdmgbuild.key -out secdmgbuild.p12
   

7. Use hdiutil with the -certificate options to create an encrypted volume (example only):

   hdiutil create -type SPARSE -encryption aes-256 -certificate ~/certsecdmg/secdmgbuild.der -fs HFS+J -volname "SecureImage" -size 100m ~/Desktop/SecureImage
   

8. Import secdmgbuild.p12 in your keychain
9. Double-click SecureImage.sparseimage, enter: password of step 3/always allow to always allow access for diskimages-helper.

10. Create a new Automator workflow, adding a Run Shell Script action with the following command:

    hdiutil mount ~/Desktop/SecureImage.sparseimage
    

    ^{(please apply paths as needed)}

    This simple Automator workflow works as "workflow" and "app".

11. Add further actions as required.
12. Save the content of the folder certsecdmg at a secure place and remove it afterwards.

Answer 2

The code in my AppleScript was causing problems.

The full automator flow is 2 Apple Scripts, one to set the variable for the file location and another to run it.

The first script:

on run {input, parameters}

    set output to "NameOfImage"

    return output
end run

The next one

on run {input, parameters}
    set imagePath to "Macintosh HD:Rest of Path:" & (item 1 of input) & ".dmg"
    tell application "DiskImageMounter"
        try
            open alias imagePath
        end try
    end tell
end run

Running the previous code in Script Editor produced an error message instead of timing out.

error "DiskImageMounter got an error: Connection is invalid." number -609

I don't know why a try statement fixed it or why it needs the alias, but there is not much information available on AppleScript.