Samsung Galaxy SIII returning different UIDs...

Asked by Juan Trujillo

Every time I put my Samsung Galaxy SIII close to my NFC board, I see a different UID. Shouldn't it be the same? If this is expected, how can I force my phone to provide the same UID always?

I'm asking this since when I use a regular/standard (Type2Tag) I always see the same UID. I need the UIDs to be the same always on my phone since I'm using this field as a key to register/unregister a user on my app.

Here are examples of the information I see on my R-Pi when I'm pairing my phone:

Type4Tag ATQ=4403 SAK=20 UID=08c0d6d1285c0e ATS=0578338802
Type4Tag ATQ=4403 SAK=20 UID=080c03fce3816a ATS=0578338802
Type4Tag ATQ=4403 SAK=20 UID=081d776f748f18 ATS=0578338802

And this is the output for a Type2Tag (always the same):

Type2Tag ATQ=4400 SAK=00 UID=0477037a8c3384



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Stephen Tiedemann (stephen-tiedemann) said :

That's pretty standard, phones do not usually have a fixed UID for card emulation (the first byte 0x08 tells that it's random).

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