Comment # 12 on bug 1201439 from Dirk Weber

A rescue system is available here (this is the current Tumbleweed):

https://download.opensuse.org/tumbleweed/iso/openSUSE-Tumbleweed-Rescue-CD-x86_64-Current.iso
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Here is some documentation how to put in on a USB stick:
https://en.opensuse.org/SDB:Live_USB_stick

BTW: if you originally installed from a USB stick and it still contains the
installation system it could work with this one, too.

The rescue system boots into a graphical desktop, and with the file manager of
this desktop it should be possible to "just mount" the encrypted partition.

I think the line
"error: ../../grub-core/disk/luks.c:311: access denied"
can mean that the decryption failed - possibly due to an invalid passphrase.
But I am not sure this is the only case in which this error message comes.
The next lines then mean that the expected cryptodisk and device which are in
the container can not be found and are the consequence of the failed
decryption.