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Remote storage

Starting with version 1.5, Disk Decipher provides support for remote storage. This allows access to disk images stored on a remote server. Disk Decipher will only download the parts of the disk image required to open the disk image and access the directories and files you select. This gives quick access to remote disk images independent of the size of the disk image.

For performance reasons, consider defragmenting your disk image occasionally. Downloading a file which is split in multiple fragments will obviously be slower than downloading a file in a single request.

To access a remote disk image simply tap the Add (+) button on the home screen of Disk Decipher, select Remote Disk and enter the URL of the remote disk image.

URL

The first remote storage protocol implemented in Disk Decipher is the HTTP protocol.

HTTP

To access a disk image using the HTTP protocol, you need to store the disk image on a HTTP 1.1 compliant server. This can be a local Intranet web server if your iPhone/iPad is connected to a local wifi network, or a web server connected to the Internet if you want to access the disk image anywhere.

Disk Decipher uses the HTTP 1.1 Range feature to download only the necessary parts of the disk image.

In version 3.8.4 the HTTP remote storage provider has been replaced with a new implementation, built upon the Network framework. This re-allows Disk Decipher to communicate (unencrypted) with HTTP servers, a feature that stopped working when Apple introduced App Transport Security in iOS 9.0.

Since encrypted disks are already encrypted, the transport of the disk data from the server to your device does not need to be encrypted. Note that HTTPS provides more than just encryption of the disk data, like server authentication, message integrity and encryption of other data (like basic authentication header).

The HTTP implementation currently supports

  • HTTP 1.1 persistent connections (this allows Disk Decipher to download multiple disk fragments efficiently, without the overhead of establishing a new connection for each individual fragment)
  • HTTP redirects to another HTTP URL
  • Basic authentication

The HTTP implementation currently does not support

  • Other authentication schemes (e.g. Digest, Negotiate or NTLM)

If needed, the URL can be protected by username/password authentication. Disk Decipher will respond to authentication requests by asking for the username and password. If the URL contains a username, it will be shown as default username. The credentials will be saved until Disk Decipher is restarted.

Note: in general, be careful with using basic authentication in combination with HTTP on an untrusted network. The username and password will be transmitted in clear-text. Consider using HTTPS instead of HTTP to encrypt the credentials automatically.

HTTPS

Version 1.7 of Disk Decipher adds support for the HTTPS protocol, i.e. HTTP encapsulated in SSL. The same requirements and comments that apply to HTTP also apply to HTTPS.

Disk Decipher actually contains two implementations for the HTTPS storage provider:

  1. One implementation based on the URLSession framework. This implementation requires the server to present a valid SSL certificate. Being based on the URLSession framework, this implementation supports several more HTTP authentication methods like Digest, Negotiate and NTLM.
  2. Another implementation based on the Network framework, which is the HTTP implementation (see above) augmented with TLS. This implementation allows additional trust for e.g. self-signed certificates.

On mounting a remote disk, Disk Decipher will try the URLSession implementation first. If the server certificate validation fails, you will be able to review the exact error and the certificate.
If the error is non-fatal (e.g. the certificate is not revoked) an option will be available to trust the certificate. This will enable the Network implementation for the remote disk.

Before trusting a certificate please read the Server Trust page.

If needed, the URL can be protected by username/password authentication. Disk Decipher will respond to authentication requests by asking for the username and password. If the URL contains a username, it will be shown as default username. The credentials will be saved until Disk Decipher is restarted.

WEBDAV

Webdav uses standard HTTP or HTTPS connections to retrieve remote objects, so provided your webdav server conforms to the requirements listed above, Disk Decipher should just work if you provide the URL to the disk image.

Disk Decipher has been tested succesfully with the following cloud storage providers:

  • Box, use URL https://dav.box.com/dav/... with ... the path to your disk image.
  • Hidrive, use URL https://webdav.hidrive.strato.com/users/username/... with username your Hidrive username and ... the path to your disk image.

Are you using WEBDAV to connect to another cloud storage provider? Let me know and I'll add the provider to this list to help others.

Here is a list of other WEBDAV URLs. Note that these URLs have not been tested with Disk Decipher. Please let me know if you successfully use one of these URLs and I will add the URL to the above list.

Dropbox

Dropbox

Version 1.8 of Disk Decipher adds support for Dropbox. Disk Decipher uses the Dropbox API to access disk images stored in your Dropbox account.

To use this feature, you need to link Disk Decipher to your Dropbox account by opening the settings dialog, and selecting "Storage provider accounts". Tapping "Link Dropbox account" will initiate the familiar procedure to link a Dropbox account.

Note: Disk Decipher supports linking multiple Dropbox accounts. If you have access to multiple Dropbox accounts, tap "Link Dropbox account" for each account. This will enable you to access disk images stored in these accounts.

After successfully linking a Dropbox account, the account will be shown with its e-mail address in the list of storage provider accounts:

Storage provider accounts

After linking your Dropbox account you can easily add a disk image stored in your Dropbox account from the main Disks view:

Dropbox New Disk

Just tap the Dropbox account, and a familiar file picker will enable you to select the disk image stored in your Dropbox account. The disk image will be added to the list of available remote disks in the main view of Disk Decipher:

Dropbox Remote Disk

The semi-random string shown at the end of the URL is the fileID of the disk image in your Dropbox.

Google Drive

Google Drive

Version 2.3.0 of Disk Decipher adds support for Google Drive. Disk Decipher uses the Google Drive API to access disk images stored in your Google Drive account.

To use this feature, you need to link Disk Decipher to your Google Drive account by opening the settings dialog, and selecting "Storage provider accounts". Tapping "Link Google Drive account" will initiate the familiar procedure to link a Google Drive account.

Note: Disk Decipher supports linking multiple Google Drive accounts. If you have access to multiple Google Drive accounts, tap "Link Google Drive account" for each account. This will enable you to access disk images stored in these accounts.

After successfully linking a Google Drive account, the account will be shown with its e-mail address in the list of storage provider accounts:

Storage provider accounts

After linking your Google Drive account you can easily add a disk image stored in your Google Drive account from the main Disks view:

Google Drive New Disk

Just tap the Google Drive account, and a familiar file picker will enable you to select the disk image stored in your Google Drive account. The disk image will be added to the list of available remote disks in the main view of Disk Decipher:

Google Drive Remote Disk

The semi-random string shown at the end of the URL is the fileID of the disk image in your Google Drive.

Microsoft OneDrive

OneDrive

Version 2.9.0 of Disk Decipher adds support for Microsoft OneDrive and OneDrive for Business. Disk Decipher uses the Microsoft Graph API to access disk images stored in your Microsoft OneDrive account.

Adding / accessing an encrypted container stored in your OneDrive account is similar to Google Drive (see instructions above). Just add your Microsoft OneDrive account under Settings - Storage provider credentials, then add the encrypted container using the + button at the top of the Disks list.

Box

Box

Version 2.9.2 of Disk Decipher adds support for Box. Disk Decipher uses the Box API to access disk images stored in your Box account.

Adding / accessing an encrypted container stored in your Box account is similar to Google Drive (see instructions above). Just add your Box account under Settings - Storage provider credentials, then add the encrypted container using the + button at the top of the Disks list.

Other protocols

The remote storage support can be extended to other protocols / cloud storage providers. If you like to see a specific protocol implemented first, then please let me know.