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#1 2018-04-22 10:06:28

jramb0
Contributor
Registered: 2016-11-07
Posts: 25

Pyramid - Checksum ae failed

Hey guys,

Trying to read a pyramid fob and I am getting the following message... "Checksum ae failed - should have been 62"

Here is an extract of the result:

proxmark3> lf search
NOTE: some demods output possible binary
  if it finds something that looks like a tag
False Positives ARE possible


Checking for known tags:

Pyramid ID Found - BitLength: 67 -unknown BitLength- (63011), Raw: 000101010138b068ae7531d03eb08cae
Checksum ae failed - should have been 62

Valid Pyramid ID Found!

Valid T55xx Chip Found
Try lf t55xx ... commands



Anyone came across that in the past?

Last edited by jramb0 (2018-04-22 10:09:30)

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#2 2018-04-22 10:26:17

iceman
Administrator
Registered: 2013-04-25
Posts: 9,497
Website

Re: Pyramid - Checksum ae failed

unknown bitlength  and checksum failed is a indication at the decoding of pyramid bits was not a precise match.

if you do

lf read 
data save pyramid.pm3

and share it via some file sharing service,  and post link here it would help out to make better detection.

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#3 2018-04-23 10:56:23

jramb0
Contributor
Registered: 2016-11-07
Posts: 25

Re: Pyramid - Checksum ae failed

here is the link

https://drive.google.com/open?id=1GYLFK3CsW7qxHmoXXGOJkvAguzOw-5pj

thanks!

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#4 2018-04-24 15:44:28

marshmellow
Contributor
From: US
Registered: 2013-06-10
Posts: 2,302

Re: Pyramid - Checksum ae failed

is there any printing on the tags?  (btw the tag you linked and the first tag you posted are different).
or do you know the card number(s)?

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#5 2018-04-25 01:54:16

jramb0
Contributor
Registered: 2016-11-07
Posts: 25

Re: Pyramid - Checksum ae failed

yeah i know the tag in the original post and the previous one are different... but the same result... here is the result of the one that i shared in google drive:

proxmark3> lf search
NOTE: some demods output possible binary
  if it finds something that looks like a tag
False Positives ARE possible


Checking for known tags:

Pyramid ID Found - BitLength: 70 -unknown BitLength- (31836), Raw: 00010101025149263b1c492586e3735b
Checksum 5b failed - should have been 29

Valid Pyramid ID Found!

That one has a the following printing on the tag... *N1867-3325570

Could that be the card number that i am looking for?

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#6 2018-04-25 03:17:57

marshmellow
Contributor
From: US
Registered: 2013-06-10
Posts: 2,302

Re: Pyramid - Checksum ae failed

that would be the card number, if you have more samples with the printed numbers it might help, but this is the Keri N series cards that borrow some of the pyramid format but don't fully follow it as it appears encrypted in some manner.  there is a thread around here somewhere on it.

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#7 2018-05-07 18:13:16

hkplus
Contributor
Registered: 2015-01-07
Posts: 127

Re: Pyramid - Checksum ae failed

The Keri N format is a Pyramid tag where the data is encypted.  This is the data in the Pyramid blocks.  No one knows the encryption at this point, perhaps except Keri smile

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#8 2018-05-08 03:08:24

jramb0
Contributor
Registered: 2016-11-07
Posts: 25

Re: Pyramid - Checksum ae failed

I see.

Just trying to figure out how to do it. have you had any experience with that one in the past @hkplus?

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#9 2018-05-08 03:34:07

hkplus
Contributor
Registered: 2015-01-07
Posts: 127

Re: Pyramid - Checksum ae failed

There is not enough to go on except for Keri's description of the card which includes 128 bit encryption.

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