Nordic ID

Introduction

EPC Gen 2v2 standard is an update to GS1's Electronic Product Code (EPC) air-interface protocol standard for passive, ultrahigh-frequency (UHF) RFID tags. 

The improvements include improved security and counterfeit detection for tagged products. The tag or reader can be authenticated with a 128-bit security key. The features included are targeted to be used for electronic article surveillance (EAS). 

ISO/IEC 29167-10 specifies the crypto suite used in this context. AES-128 for the ISO/IEC 18000 defines the crypto suite for security for RFID devices. 

ISO/IEC 29167-10 specifies the authentication methods and usage of the encryption algorithm. A tag can support one, a subset, or all of the specified options.

Authenticate command

Authenticate tag crypto key

The Authenticate command can be used to verify the tag's identity. Verification is done against a 128-bit key stored in the tag memory. 

An example of how to use Nordic ID NurApi is shown here:

public bool ISO29167_10_TAM1(byte keyNum, byte[] key);

keyNum is the index of the key

key is array of 16 bytes i.e. 128 bits

return value

True – the key in tag matches the key sent

False – no match, authentication failure

See also ISO29167_10_TAM1ByEPC() and ISO29167_10_TAM1Singulated().

Authenticate a memory block

The Authenticate command can also be used to read an encrypted memory block. A Nordic ID NurApi helper function can be used to easily populate the Authenticate parameters.

public static TAM_PARAM AllocTAM2Param(

byte keyNum, 

byte[] keyData, 

uint blockCount, 

byte mpi, 

ushort offset, 

byte protMode)

The actual command to execute reading an encrypted memory block is:

        public TAM_RESP ISO29167_10_TAM2(TAM_PARAM tamParam)

Here the tamParam is the return value of the helper function. TAM_RESP can be initialized with a call to function AllocTAMResp() which initializes the response object. See also ISO29167_10_TAM2ByEPC() and ISO29167_10_TAM2Singulated().

The response to Authenticate memory block command has the following structure:

          public class TAM_RESP

          {

                    public bool response;

                    public bool ok;

                    public uint C_TAM;

                    public uint TRnd32;

                    public uint szBlocks;

                    public byte[] challenge;

                    public byte[] firstBlock;

                    public byte[] blockData;

                    public byte[] cmac;

     }

Where the return values indicate the following:

Untraceable command

The Untraceable command can be used for two purposes.

1. To limit the operating range of the tag.
2. To untraceably hide memory from a reader not set up with the untraceable privilege.

The Nordic ID NurApi command format is shown here:

        public void Gen2v2Untraceable(uint accessPwd, UntraceableParam utrParam)

The correct Access password is mandatory when using the Untraceable command.
The Untraceable parameters are:

    public class UntraceableParam

    {

        public bool setU = false;

        public bool rxAttn = false;

        public bool hideUser = false;

        public bool hideEPC = false;

        public int epcWordLen = 6;

        public int tidPolicy = NurApi.TID_HIDE_NONE;

        public int rangePolicy = NurApi.UTRACE_RANGE_NORMAL;

    }

References

|1| EPC® Radio-Frequency Identity Generation-2 UHF RFID Standard

https://ref.gs1.org/standards/gen2/

|2| ISO/IEC 29167-10:2017 Information technology – Automatic identification and data capture techniques

Part 10: Crypto suite AES-128 security services for air interface communications

https://www.iso.org/standard/69410.html