[HECnet] TOPS-10 Fortran V11 patch decryption keys

Speaking about compilers... TOPS-10 (and TOPS-20) TSU patches were distributed in encrypted form, the idea being that only people having keys that were delivered with original product tapes could decrypt them. In fact TSU tapes contain almost complete versions of most licensed Digital products. Unfortunately, the tape image of the Fortran-10 V11 product tape available on both Trailing Edge and Bitsavers is truncated and lacks the saveset with the keys. It should be the 7th saveset, but the image ends after the 4th. Does anyone here have some idea about how to overcome this problem? Or, even better, does anyone know if there could be another copy of the same tape available somewhere? I've found that the Computer History Museum has a copy (https://www.computerhistory.org/collections/catalog/102773759) and I wonder if it's the one from which the truncated image was sourced. The tape identifier is BB-D480G-SB. Alternatively I think it might be possible to build the TOPS-10 FORTRAN V11 compiler with the patched sources of the TOPS-20 compiler, in fact they should share almost everything except maybe OS interfaces like SCAN, WILD, COMND, and so on... Thoughts? :) G.