Terminology confusion

So after hanging around here for a while and exploring various options, i realized that I have no clue about almost any of the terminology used. I know that hf and lf are different frequencies and that impacts compatibility with different readers and NFC is a hf standard commonly used on phones… that’s about it
This also seems like a useful thread to make for other newbies

  1. Mifare, what is it and what can I do with it?
  2. same with DESFire
  3. what is the difference between all of these ISO##### I keep seeing?
  4. flex vs capsule. Is there any difference other than the form factor and placement options?
  5. UID is it kinda just a unique ID number?
  6. I’ve also seen T#### numbers, what are these/ what are the differences?
  7. I’ve also seen NTAG### used, what are and what’s the difference?
  8. finally the different ##bit ids, is that just different length UID?
    Thanks to anyone willing to chip in here
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Have you checked the faqs and Wikis…there are answers to almost all of your questions in there

also check out
the DT Youtube channel
DT web page for each product you asked about
the product matrix on THIS link

Looks like AMAL is currently answering you, so I will leave it in his more capable hands…

actually how do i get to the wikis and faqs?
i know the product matrix but i dont think that that page explains what the tags mean…

ooohhhhhh ok, i assumed it would be through the main site, not the forum. ill take a look through that while amal seemingly types up an essay lol

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HF is “high frequency” and means 13.56MHz

LF is “low frequency” and means 125kHz - 134kHz and for all intents and purposes they are the same. For example, the Halo reader can read both 125kHz and 134kHz tags with the same antenna because basically they are so close they are the same when it comes to coupling. The major differences between any RFID tags is the protocols, memory structures, data encodings, and command sets.

  1. Mifare is a marketing term that has been bastardized so badly it’s almost meaningless now. Even NXP’s information on the term is muttled by marketing-speak (NXP owns Mifare trademark)… but basically it means a certain type of 13.56MHz transponder that has a specific memory structure and types of commands it responds to over the ISO14443A RF protocol. The most common and legacy type of “Mifare” card is the classic Mifare S50 1k card. It has specific 1k memory structure split into multiple sectors, each with their own keys and access bits… I wrote a little paper a while back because working with these tags can be confusing as all heck… NFC-Access-Control-for-Mifare-S50.pdf (631.1 KB)

  2. DESFire is a specific type of chip, and unlike Mifare, it has not yet been corrupted by marketing-speak… there are multiple “evolutions” of the DESFire chip… the D40 which used proprietary encryption ans has been cracked… then the DESFire EV1 (evolution 1) which supports 3DES keys and multiple AID “files” you can split the memory up into, and the DESFire EV2 (evolution 2) which supports AES and 3DES and has more features (check dngr.us/xdf2 product page for data sheets etc.)

  3. The ISOs are standards (like every other ISO out there)… for example ISO 9001 is a manufacturing process and documentation standard… but when it comes to RF protocols or (air interfaces), there are a few key ones… ISO14443 (comes in A & B flavors) which is also called “proximity”, as well as ISO15693 which is also called “vicinity”. Both are popular 13.56MHz RF protocol standards used by RFID based systems all over the place… though when it comes to NFC, ISO1443A is typical for NFC compliant RFID tags defined as NFC Type 1 through 4 by the NFC Consortium, and then there’s NFC Type 5 which is based on ISO15693.

  4. Flex is a biopolymer encapsulated device which tends to be very thin, somewhat wide, and most importantly has a flat plane antenna coil which allows it to couple much more efficiently with basically every reader out there. This is because readers typically have antennas which are also flat spiral planes, usually printed on PCB as copper traces, or sometimes made or wire. The down side is they require a little more effort to install. The “capsule” or “ampoule” style tags (what we call our x-series) are glass encapsulated and inside the antenna is a cylinder shape, typically wrapped around a ferrite polymer rod. This can limit the effective energy the chip is able to induct from a reader due to the shape not matching the shape of a typical reader antenna. The advantage is that they are easily installed by way of injection. Placement of a glass device should be done away from bone since pinching between bone and an external blunt force could increase risk of breaking… though we’ve never had a confirmed physical break from this and we’ve tested the heck out of our stuff. Flex devices don’t have that sort of limitation, but it’s best to not place flex devices where there could be skin tension or a lot of flexion.

  5. Yes… UID means Unique ID… though some RFID types like the Mifare “classic” 1k chips only have a 4 byte ID and because these chips are still made, they’ve had to roll-over their IDs … so now they call them “NUID” for non-unique ID… but never trust that these ID’s are actually unique… manufacturers in China will not only make up their own IDs and ignore things like manufacturer’s ID prefixes that are supposed to keep each manufacturer’s list of IDs unique without needing to share a giant list… but they also make chips you can use to clone UIDs from other cards… effectively making copies… this is one of many reasons why UID based security systems (terrifyingly popular) are not secure in the slightest.

  1. If you are referring to the T5577 and others… this is a special type of chip made by Atmel which is a 125kHz chip which is totally programmable both in terms of ID and memory space, but also analog front end… so the chip can literally change how it talks to readers. This makes it a very versatile chip which is capable of “emulating” really a lot of other chip types in the 125kHz insecure “security” space… so like HID ProxCard, AWiD, Indala… they all have 125kHz chips which have slightly different ways of speaking their IDs to readers, and the T5577 can emulate them all, which can be quite useful for an implant. That’s why we put the T5577 into the xEM and NExT products.

  2. The NTAGxxx is another type of chip from NXP… it’s not “mifare” … but it is very similar to the Ultralight product line, which SOME people call “Mifare Ultralight”… which is irritating… so again, if you’re talking about Mifare as a specific type of memory schema and command set, Ultralight and NTAG chips are not that… but if you are talking about Mifare as a marketing term for a “family” of tag types with no association at all to their technical specifications, then Ultralight is known to be “within the circle” of the “Mifare family”, but NTAG… so far… is not included… yet… probably… FML.

  3. Yes… just different number of bits per ID… the reason bits are important unit of measure is that there are sometimes odd bit lengths for IDs which contain other information like CRC check data etc… and the total number of bits do not add up to a clear byte count… 8 bits per byte is great but what about a 24bit ID? how many bytes is that? it’s a fractional number so yeah… bits are where it’s at… it also helps avoid confusion with “characters” or “digits”… some people say “I have a tag with a 10 digit ID” … that is meaningless… 10 digits? do you mean binary data expressed as decimal numbers? hexadecimal? bytes or characters or digits? In the end it’s all binary data, but it can be expressed in so many different ways that unless you use bits to describe data length, it can get very confusing.


Thanks a ton Amal! you have to be the most active founder in their own community ive seen… ever. thanks a ton for that!
In summary to clarify, mifare is… complicated, DESfire is a chip type with different generations with different features, ISOs are the communication standard that has to match between reader and chip, flex has more range and placement options, UID is the ID, T#### are chip types and the T5577 is amazingly flexible, and NTAG is another chip type complicatedly related to mifare
do i have that right?
also you mentioned NFC types, what are the differences there?

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oh also @amal im reading through one of the faqs and you seem to think that software devs are lazy. ill be in college next year minoring in software dev and i can confirm that yes, we are absolutely lazy as hell lol.

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Yeah basically that’s the gist :slight_smile:

haha well I recognize that often times scope of the project doesn’t allow for “doing things the right way”… but yeah… often times it’s laziness… though, still not as absolutely god awful as marketing people :wink:

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perfect, thanks for the help again, you’re the best! I plan on getting a NExT when i turn 18 in june (just need to find someone to implant as i live near rochester ny and the closest partner is a plane ride away) and the flex one or whatever it will be called later on. Super exited!

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I see what you did there :slight_smile:


Wow i didnt even intent that lol. good spot