[mkgmap-dev] Recent Garmin Firmware "cannot authenticate maps" when they are unicode

Mon Aug 28 13:55:16 BST 2017

Hi,

I tested the dach_boundary_gmapsupp_error.img…

On a etrex 30 : no message "cannot authenticate maps" and boundaries are
visible.
On a GPSMAP64s : error message "cannot authenticate maps" and the map is
not listed.

Steph

Le 26/08/2017 à 23:01, franco_bez a écrit :
> Hi Gerd and Andrzej,
> 
> I do not see any reason why GARMIN should only require UNICODE maps to be
> signed, while LATIN1 maps can remain unsigned.
> 
> I suspect that there is a flag in the file header, maybe a new and
> undocumented one, that marks the file as "check for signature".
> When the Oregon checks the signature, and finds out that there is none, it
> states that the check failed.
> 
> Maybe mkgmap accidentally marks the file as "to be checked for signature"
> when it writes out a unicode map.
> 
> Does this soud plausible to you ?
> 
> I uploaded a sample map that produces the error, it just contains
> administrative border lines as an overlay layer. I'm not sure whether it
> contains an index or not .
> http://files.mkgmap.org.uk/download/356/dach_boundary_gmapsupp_error.img
> 
> I can do a little testing if you can provide me with test cases.
> 
> Ciao,
>   Franco
> 
> 
> Am 26.08.2017 um 06:59 schrieb Gerd Petermann:
>> Hi Franco,
>>
>> my understanding is that this is not a bug, but a limitation implemented
>> by Garmin.
>> My mothers Nüvi also doesn't load unicode maps.
>> One reason might be that some indexes don't work with unicode and mkgmap
>> doesn't
>> write the needed ones. I cannot try that now.
>> If the 750 loads a unicode map without an index we may have a chance by
>> doing more reverse
>> engeneering of old maps.
>> On the other hand, I wonder how long they will the support the old img
>> format written by mkgmap,
>> maybe this is the first step to drop this support.
>>
>> Gerd
>>
>> ________________________________________
> Am 26.08.2017 um 11:51 schrieb Andrzej Popowski:
>> Hi,
>>
>>> my understanding is that this is not a bug, but a limitation
>>> implemented by Garmin.
>>
>> This is true. Garmin maps can be digitally signed. Many new GPS require,
>> that Unicode map include signature. Signature is a protection against
>> tampering, which is reasonable for commercial maps, but it exclude support
>> for 3-rd party maps.
>>
> 
> 
> 
> 
> 
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