It's the SLA1 signature on the end of each metaindex2.txt protects each file from tampering / download issues. They are signed with a private key but read as valid with the public key. Not convinced that something else isn't missing from those files in the Seat part number in any case. I did spend a long time looking at those files at times.
Normally you re compute the check sums but the signed SLA1 signatures if being used on that part of the update are the stumbling block. Navigation update is one of the ones that requires the signatures to be valid. POI updates, no which is how POI developers generate update files.
The VAG public key is known whilst the private key isn't. It's the same key on all VAG products.
My journey on the subject is here:
The MIB2 cards at least have a hidden partition on them, they are special SD cards http://www.seatcupra.net/forums/showthread.php?t=388586&page=26 It was notabenem in November started this one off in post 501 with those key filenames. Then it was Exciter that found the patent to the...
www.seatcupra.net
Mathematical algorithm is used with the public key to validate the signature but you can't create the signature if you dont have the private key. All VW private keys are the same since the public key is the same. You need a fair bit of computer power, £100,000 of it was a quoted figure on sla1 signatures a few years back to decode the primary key.
I did try a published exploit which is used to get mib tools into the unit to put the part number in. I think that said exploit has limitations so it didn't work. Mib tools rides into the back of a radio station update by putting the payload after the signature.... They forgot about that one in the mib2 design. If the signature was to protect the payload above that's achieved, but not anything going in after. So whilst it works to get that code in, doing that on a big map upload it didn't. They did have teething problems getting mib tools in, you can read that online before they perfected the SD import. It generated assorted error codes.
Seat are now pretty timely with the publication of the maps. They have been known to publish quarters outside of the main six month cycle on production cars. May be if it was a terrible mistake then you might see a 193 or 194 or something. I doubt it thou.
Custom firmware is the way ahead for 192 and Seat mib2 high. I could be surprised and see Seat producing the map download and it's all been a big mistake but doubt it. As far as Mapcare is concerned that will be running out on many units which is the advantage of custom software. Mib2 updates have another four years to run following published mib1 timelines. + 5 years onto discontinuation. 2025. VW and Skoda will enjoy that.
I'm still bugged by whether a full list of FeC codes messes up TSR. I'm told by a UK retrofitter that the issue of MPH signs being read as KPH is due to too many FeCs in the payload (known issue in the retrofitter world apparently). Whilst this issue may not bother drivers in Europe or those without TSR in the UK, it would otherwise. Took my previous retrofitter all afternoon to correct it with many goodbyes and returning again 10 mins latter (speed warnings at 1/2 the legal speed are pointless). Would be interesting to hear whether any Seat UK drivers with TSR have had success with this. Intend to use a retrofitter now to manage this issue in the firmware change. Others have pointed to the FeC being a European one in the past. Previous retrofitter went back to my old settings and reloaded. That fixed it (could be they studied what was in the working FeC container file and the one they put in, corrected but said nothing of their error).... hence why professional are a good idea at times
. Mind you they introduced the
problem.
.
.
. 
. They are the Poinspector imports. Get one each time I import user POIs.
