What Is a Blocking Card and How Does It Work?
Discover how a simple blocking card safeguards your financial information from modern digital skimming threats. Understand its protective function.
Digital card skimming presents a modern challenge to personal financial information. As transactions increasingly occur without physical contact, data on payment cards becomes vulnerable to unauthorized access. Awareness of protective measures is essential to secure personal financial data.
Understanding Blocking Cards
A blocking card is a physical card designed to protect other cards from unauthorized scanning. It prevents digital skimming, a form of electronic pickpocketing, from contactless cards like credit cards, debit cards, transit passes, and identification cards. These cards use Radio-Frequency Identification (RFID) or Near Field Communication (NFC) technology for wireless data transmission.
RFID and NFC allow for convenient contactless payments and access control by transmitting data over radio waves. This wireless capability creates a vulnerability. Skimmers can illegally read card data from a distance, often from a few centimeters up to 10cm, using portable scanning devices. This unauthorized access to card numbers, expiration dates, and personal identification can lead to fraudulent transactions or identity theft.
Digital skimming involves criminals using unauthorized readers to capture data from RFID-enabled cards. This method differs from physical skimming, which attaches devices to ATMs or point-of-sale terminals.
How Blocking Cards Provide Protection
Blocking cards provide protection through passive shielding. They contain materials like metallic layers or specialized fabrics that interfere with electromagnetic fields. This creates a protective barrier around your cards, disrupting radio frequency signals used by skimmers.
When placed near RFID-enabled cards, a blocking card absorbs or reflects incoming radio waves. This prevents unauthorized scanners from reaching your cards’ embedded chips. The blocking card ensures the RFID chip cannot receive enough power to transmit data, preventing it from being read.
Some blocking cards use active “jamming” technology, where an embedded microchip scrambles incoming RFID signals. This method sends out an interfering signal, causing a card clash issue or draining signal power. Passive shielding is generally sufficient for protecting contactless payment cards.
Practical Use and Considerations
Using a blocking card is straightforward. Typically, one card can protect several others if positioned correctly within a wallet. Most blocking cards are the size of a standard credit card and should be placed alongside your RFID-enabled cards to create the protective shield. For optimal protection, placing the blocking card in the front or back of your stack of cards, or even sandwiching them, can be effective.
When selecting a blocking card, ensure it is designed for the 13.56 MHz frequency used by most payment cards. Options include standalone blocking cards, wallets, or sleeves with built-in RFID-blocking materials like aluminum or copper. These materials vary in effectiveness, with some offering more robust protection than others.
Blocking cards protect only against digital skimming of wireless signals, not against physical theft of a wallet or its contents. They are designed not to interfere with legitimate card use; you typically remove the specific card from your wallet to tap it for payment. While multiple contactless cards together might cause interference, a dedicated blocking card offers a more reliable defense against unauthorized scanning.