Using ISO 15693 tags for

Authentication

Eddie LaCost

Embedded RF

Authenticated RFID Model• Signature is generated using

hash of tag UID and private key.• This signature is programmed

and locked to the tag during manufacturing.

• Reader must also know private key.

• To authenticate tag, reader will first read the UID and all memory blocks of the tag.

• Reader will hash the UID with the secret key to generate the signature and compare to the signature of the tag.

• HASH Suggestion: SHA1 (160bit)• Time for Authentication (28.8 ms)

MSP430

UIDHASHSecret Key Signature

TAG

Reader

UIDHASH

Secret Key

TagSignature

Signature If equalAuthenticate

Authentication TimeUID Inventory = 6mS, Read Single Block x5=22.8mS.  Total time of 28.8mSPerform SHA1 Hash in Reader as soon as UID from Tag is read. It would runin parallel to reading out Hash from Tag. Estimated time for HASH operation in reader @ 1ms

Advantages• Security: proposed scheme offers a certain level of

security using Private Key Authentication compared to simple UID verification

• Memory Saving: With Hash function technique, the Reader needs to know the Private Key only and there is no need to store UID of every Tag in the reader

• Authentication time in ms – very fast and suitable for application

• Small form factor of tags may make counterfeit tags difficult

• Extra “road block to counterfeiting” available using custom commands (next slide)

“Road blocks to Counterfeiting”• Tag-it HF-I Pro offers “write block with password”

command. Password is 32 bits long.• Tag must be programmed & locked with password and

Reader must also know password• Using “Inventory with AFI”. If correct AFI(application

family identifier) is not written to the tag, it will not respond to the readers “inventory” command. This is an 8 bit block. Can be locked.

• Using DSFID(data storage field ID) block. DSFID is not a part of the main user memory blocks. Using this memory to write some extra data could deter cloning as this field may not always be checked. This is an 8 bit block.

Vulnerabilities

• Data is not encrypted over the air - deemed low risk of exposure.

• Unless used UID are checked against a database for duplicates & follow up revocation, counterfeited tags could still be validated.

• Public key would not provide higher level of security for anti-counterfeiting. Vulnerabilities for exposure of information on the Tag and scheme to access a database for comparison and revocation remain weak points in both public and private key.

TI IC & Software Offerings

In addition to Tag, Reader and MSP430 solutions, TI can provide optimized SHA1 code