rename - sort recovered image files with exif data to existing files

I managed to recover lots of images (canon cr2 + accompanying jpg) from a failing hard-drive with recurva.
It created a lot of files with some sort of hash-filename. So it is a bit complicated to sort the files into their appropriate folders and/or rename them back to their original name.
But all these image files still have valid exif data stored with them. So it is possible to read the correct file creation date and such.

Is there any automated method ready that could help me sort and rename them via that exif data?

Answer

I found out that the great tool digikam is able to do this via gui. It has exiv2 included and can use it for batch rename and so much more!