How do I change the password on dmg file created by Disk Utility?

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Level 1

10 points

How do I change the password on dmg file created by Disk Utility?

The password I've created for my .dmg file, containing all my secrets and sensitive information, is lame. I'd like to create a more secure one... any hints?

Many thanks,

Dave

MacBook Pro, Mac OS X (10.6.2), Snow Leopard upgrade installed

Posted on Dec 23, 2009 12:20 PM

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Answer 1

V.K.

Level 9

56,174 points

Dec 23, 2009 12:25 PM in response to dceflyer

that's not possible. make a new encrypted image with the password you want. use a sparse image or a sparse bundle instead of a regular image to save space. then copy the contents of your old image to the new one.

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Answer 2

V.K.

Level 9

56,174 points

Dec 23, 2009 12:51 PM in response to V.K.

strike that! it's possible to change the password without creating a new image. it can be done from terminal. run the following terminal command


hdiutil chpass path/to/image

put the unix path to the image in the command. the easiest way to get it is to drag the image to a terminal window. make sure the spaces in the command are there as in the above example. it will prompt you fro the old and the new passwords.

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Answer 3

dceflyer Author

Level 1

10 points

Dec 24, 2009 3:41 AM in response to V.K.

Many thanks for the info, although I'm definitely not a UNIX terminal guy. Before I give this a shot, however... I saw hints around here that one might be able to unencrypt an image and then re-encrypt with the new password. Have you had any experience with this?

Again, many thanks for your help!

Dave

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Answer 4

V.K.

Level 9

56,174 points

Dec 24, 2009 7:15 AM in response to dceflyer

no, I don't but how is this different from just changing the password? why would you possibly want to do it that way?

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Answer 5

dceflyer Author

Level 1

10 points

Jan 28, 2010 2:23 PM in response to V.K.

Sorry for the long delay in replying...

You asked "why would you want to do it that way?" It's because I don't have much familiarity with Unix, and my immediate reaction is to not mess things up. But this looks simple enough -- although what characters would go before the path? (I know you'd use "C:\topfolder\filename.dmg" in DOS). The file's in my "Documents" folder, by the way.

Many thanks for your suggestions!

Dave

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Answer 6

V.K.

Level 9

56,174 points

Jan 28, 2010 2:36 PM in response to dceflyer

to get the correct path just drag the disk image to the terminal window. make sure there is a space right before the path just as in the example I gave you.

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Answer 7

dceflyer Author

Level 1

10 points

Jan 29, 2010 7:44 PM in response to V.K.

Worked like a charm... many thanks!

Dave

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