3

Using macOS Sierra: Disk Utility > File > New Image > Blank Image..., I created an encrypted .dmg file.

However when I open this .dmg (by entering password) and click "Info" in disk utility, it says:

Is encrypted: No

As I want to store some sensitive info (Credit Card info etc) in this disk and then upload it to cloud storage, I am worried if there is a bug in Sierra causing .dmg files to not be encrypted at all!

Is this normal? How can we verify if the disk is actually encrypted?


P.S. My filevault is On, and for my own Macintosh HD disk utility info says Is encrypted: Yes

4

The proper command to check if a dmg is encrypted or not is:

hdiutil isencrypted /../../encrypted.dmg

or more detailed with the encryption type:

hdiutil imageinfo /../../encrypted.dmg

Examples:

hdiutil isencrypted /Users/user/Desktop/Untitled.dmg
encrypted: YES
blocksize: 512
uuid: 24895029-49B1-469D-A154-B8344B7CD6EB
private-key-count: 0
passphrase-count: 1
max-key-count: 1
version: 2

and/or

hdiutil imageinfo /Users/user/Desktop/Untitled.dmg
<Enter disk's password>
Backing Store Information:
    URL: file:///Users/user/Desktop/Untitled.dmg
    Name: Untitled.dmg
    Class Name: CEncryptedEncoding
    Encryption: AES-256
    Backing Store Information:
        URL: file:///Users/user/Desktop/Untitled.dmg
        Name: Untitled.dmg
        Class Name: CBSDBackingStore
Class Name: CRawDiskImage
Checksum Type: none
Size Information:
    Total Bytes: 100020736
    Compressed Ratio: 1
    Sector Count: 195353
    Total Non-Empty Bytes: 100020736
    Compressed Bytes: 100020736
    Total Empty Bytes: 0
Format: UDRW
Format Description: raw read/write
Checksum Value: 
Properties:
    Encrypted: true
    Kernel Compatible: false
    Checksummed: false
    Software License Agreement: false
    Partitioned: false
    Compressed: no
Segments:
    0: /Users/user/Desktop/Untitled.dmg
partitions:
    partition-scheme: GUID
    block-size: 512
    partitions:
        0:
            partition-name: Protective Master Boot Record
            partition-start: 0
            partition-synthesized: true
            partition-length: 1
            partition-hint: MBR
        1:
            partition-name: GPT Header
            partition-start: 1
            partition-synthesized: true
            partition-length: 1
            partition-hint: Primary GPT Header
        2:
            partition-name: GPT Partition Data
            partition-start: 2
            partition-synthesized: true
            partition-length: 32
            partition-hint: Primary GPT Table
        3:
            partition-name: 
            partition-start: 34
            partition-synthesized: true
            partition-length: 6
            partition-hint: Apple_Free
        4:
            partition-UUID: 17698BE2-A406-43AA-9195-8D1F1AAECE6B
            partition-name: disk image
            partition-hint-UUID: 48465300-0000-11AA-AA11-00306543ECAC
            partition-start: 40
            partition-number: 1
            partition-length: 195280
            partition-hint: Apple_HFS
            partition-filesystems:
                HFS+: 
        5:
            partition-name: GPT Partition Data
            partition-start: 195320
            partition-synthesized: true
            partition-length: 32
            partition-hint: Backup GPT Table
        6:
            partition-name: GPT Header
            partition-start: 195352
            partition-synthesized: true
            partition-length: 1
            partition-hint: Backup GPT Header
    burnable: false
Resize limits (per hdiutil resize -limits):
 min     cur     max 
36072   195280  60572704

I can only guess why diskutil doesn't show that the image is encrypted. It's either a glitch or diskutil only rates FileVault as disk encryption.

  • Thank you very much, it works perfectly, tried to up-vote as well, but apparently I don't have 15 points to do so. – T. Rex Dec 26 '16 at 17:03

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