Asymmetric Card Authentication Key (CAK) challenge-response is an effective control in preventing electronic cloning of RFID based access cards. RFID based access cards are contactless cards that use radio frequency identification (RFID) technology to communicate with a reader and grant access to a physical or logical resource. RFID based access cards are vulnerable to electronic cloning, which is the process of copying the data and identity of a legitimate card to a counterfeit card, and using it to impersonate the original cardholder and gain unauthorized access. Asymmetric CAK challenge-response is a cryptographic technique that prevents electronic cloning by using public key cryptography and digital signatures to verify the authenticity and integrity of the card and the reader. Asymmetric CAK challenge-response works as follows:
The card and the reader each have a pair of public and private keys, and the public keys are exchanged and stored in advance.
When the card is presented to the reader, the reader generates a random number (nonce) and sends it to the card.
The card signs the nonce with its private key and sends the signature back to the reader.
The reader verifies the signature with the card’s public key and grants access if the verification is successful.
The card also verifies the reader’s identity by requesting its signature on the nonce and checking it with the reader’s public key.
Asymmetric CAK challenge-response prevents electronic cloning because the private keys of the card and the reader are never transmitted or exposed, and the signatures are unique and non-reusable for each transaction. Therefore, a cloned card cannot produce a valid signature without knowing the private key of the original card, and a rogue reader cannot impersonate a legitimate reader without knowing its private key.
The other options are not as effective as asymmetric CAK challenge-response in preventing electronic cloning of RFID based access cards. Personal Identity Verification (PIV) is a standard for federal employees and contractors to use smart cards for physical and logical access, but it does not specify the cryptographic technique for RFID based access cards. Cardholder Unique Identifier (CHUID) authentication is a technique that uses a unique number and a digital certificate to identify the card and the cardholder, but it does not prevent replay attacks or verify the reader’s identity. Physical Access Control System (PACS) repeated attempt detection is a technique that monitors and alerts on multiple failed or suspicious attempts to access a resource, but it does not prevent the cloning of the card or the impersonation of the reader.
