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  1. #151
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    Quote Originally Posted by dandreye View Post
    OK, so this data is always there in locked images as well, it's just not displayed by gmaptool as it's encrypted. Unlocking = just decoding this data.

    From John Mechalas, Garmin's IMG Format:

    If a map is locked, indicated when (0xD)!=0x00 in the subfile header, then the map's level section is encrypted with an unknown algorithm. This renders the map level information essentially unreadable.
    ...
    This encryption is obviously to prevent an unauthorized rendering engine from parsing the object hierarchy of the map. Without the zoom levels and the number of subdivisions in each level, it is impossible to know what objects to display, and when.
    Yes, this is correct basically. In a locked map, the map level data is encrypted but Garmin's firmware and navigation software can decrypt it so there is no problem to use a locked map. On the other hand, a non-locked or unlocked map must have this map level data in clear form (i.e. not encrypted). Therefore gimgunlock has to decrypt this map level data, in addition to flipping the lock bit.

    IMHO, the author of gmaptool should have the skill to decrypt the map level data (read only) and display its content. Maybe for legal or other reasons he/she chose not to decrypt it, so all locked maps will not have this map level data displayed.

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  3. #152
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    IMHO, the author of gmaptool should have the skill to decrypt the map level data (read only) and display its content. Maybe for legal or other reasons he/she chose not to decrypt it, so all locked maps will not have this map level data displayed.
    Yes, the algorithm ( and its translation in perl or C) can be found on the web ...
    I have also tested it in ImgTool but , for legal reasons, I have decided to hide this functionality in the public versions...

    There is also a confusion about the terms "locked" and "unlocked".
    According to Garmin terminology (as it can be seen in Basecamp for example) :
    - a map with a clear (non encrypted) level section is called "Not lockable" : the byte 0xD is set to 0x00 and all devices can display the map.
    - a map with an encrypted level section is lockable : for example, if you try to use it in Basecamp , without entering a valid unlock code, the map will be called "Locked" and Basecamp won't display the map, but if you enter a valid unlock code in Basecamp, the map will be called "Unlocked" and Basecamp will fully display it . So, there is no difference between a locked and unlocked map : the data is the same, the img file is the same, the difference is just that , if the rendering engine has the valid unlock code, it would "accept" to decrypt the level section and display the map.

    But, when you use an unlocker, you change your map in a "Not lockable" map :the encrypted level section is replaced by a clear ( non encrypted) level section, so thaat all devices and rendering engines can display it.

  4. #153
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    Quote Originally Posted by sherco40 View Post
    But, when you use an unlocker, you change your map in a "Not lockable" map :the encrypted level section is replaced by a clear ( non encrypted) level section, so thaat all devices and rendering engines can display it.
    You're right. Thanks for the clarification. When I said "unlocked" maps in my previous post I was referring to those maps converted from "Locked" to "Not Lockable" by an unlocker, in the context of this thread. Maybe a better term for this kind of maps is "Delocked", meaning maps with lock removed.

    I have found it necessary to distinguish between no-shift (such as topo), shift-added (official CN) and shift-corrected (Venus) maps for China. We may need to distinguish between not-lockable, locked, unlocked and delocked maps sometimes.

  5. #154
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    Quote Originally Posted by syzygy View Post
    ....... I was referring to those maps converted from "Locked" to "Not Lockable" by an unlocker, in the context of this thread. Maybe a better term for this kind of maps is "Delocked", meaning maps with lock removed. .........
    I agree that "Delocked" is a far better and more accurately descriptive term. Another possible alternate term would be "Decrypted" for "Not Lockable". The only problem is that Garmin programs' terms are of course going to continue to be "Locked", "Unlocked" and "Not Lockable", so if we then use any other (albeit better) term it may just create more confusion than it alleviates.

    As for the the China maps example (non-shifted; shift-added; shift-corrected), my recent unintentional self-coined sloppy use of "Venus Shifted Version" when i meant "Venus Shift-Corrected Version", while absolutely not an example of a better term, is an example of why we shouldn't introduce 'non-standard' terms.

    Sometimes 'non-standard' terms are totally necessary when the official term is not known at the time, and a good example of that is with FID PID RgnID VenID (short for Vendor ID). My understanding is that the fourth value is in fact a 'Sub-Region ID' or similar, but when it was first noted and discussed as to it's possible source and meaning, it was suggested by our very capable friend syzygy in long ago musings on another forum that the 4th value was perhaps 'a Vendor Identification'. The name stuck and it causes no confusion imo, even though it's quite apparently not an accurate description of that number.

    I believe that's the same with 'Unlocked' and 'Not Lockable', in that they may not be thoroughly accurate descriptions in an intuitive sense and are certainly initially confusing to a novice user who would justifiably think that 'unlocked' and 'not lockable' should mean the exact same. By that, i'm also saying 'unlocked' doesn't mean what it intuitively sounds like either, because it doesn't mean 'decrypted' which is what a 'not lockable' image is ..... So, I think best leave well enough alone - 'a rose by any other name etc'.
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  6. #155
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    It is a GOOD TOOL,I don't need installing the download program

    !!

  7. #156
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    Hi,
    The Mac part of unlocking did not work...
    Says some invalid binary...

    Thanks,
    Gold

  8. #157
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    Quote Originally Posted by golddharma View Post
    Hi,
    The Mac part of unlocking did not work...
    Says some invalid binary...

    Thanks,
    Gold
    we had different feedbacks in this thread, may be it is worth to read it
    Quote Originally Posted by warblade52 View Post
    I am using MAC for a long long time.... This tool is working like a charm on MAC. I am using it on MBPro, MACMINI SERVER and MBAir... Terminal option, I found better.. This makes the life so easy, instead of going back and forth between MAc and WMware Win 7..

    Tested maps on 765, 880, 1490, 3790, 640 and 3590 without any problem..

    nice work guys..

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    You have to navigate to get to the good.
    Nuvi1250/Nuvi 34xx/Nuvi 2200/Nuvi 66/Oregon 600/Galaxy S5 MM 6.0.1/TomTom GO/iGO Nextgen Avic,Basar,Isr.Gift/Navigon
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  9. #158
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    He had not discovered this program and I was impressed. Works great and I have already forgotten wait long to unlock maps.

  10. #159
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    Quote Originally Posted by sherco40 View Post
    Yes, the algorithm ( and its translation in perl or C) can be found on the web ...
    I have also tested it in ImgTool but , for legal reasons, I have decided to hide this functionality in the public versions...
    Could you please point to some places on the web where the algorithm is described? I coudn't find anything more then the gimgtools, though I searched quite thouroughly. Thanks!

  11. #160
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    I am having problems with my garmin 4212. I have a unlocked card that works fine with my garmin 640 but not with my garmin 4212. Any Ideas?
    I Detects the chart but at the end says chart bloqued.

 

 
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