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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)

iceman

Administrator

Registered: 2013-04-25

Posts: 9,538

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.

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!

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)?

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?

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.

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

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?

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.