Culver City (CA) - Yesterday we reported about the "StrongHold" bag that promises to block signals that aim to access data stored in RFID chips of newer U.S. passports. Paraben has since sent us a few bags for a brief test.

See the Paraben Passport StrongHold bag in detail ...

While the bags are primarily meant to block RFID signals, Rob Schroader, president of Paraben, told us that they will block other signals such as mobile phone signals just as well. In fact, the StrongHold bags are very similar to the "Wireless StrongHold" mobile phone forensic bags that Paraben has sold for years. It basically is a flip-open design that is commonly used for travel wallets. There is an inside pocket that is designed to hold the passport, which means that a device such as a passport or cellphone is protected from two layers of a Paraben uses a of a copper, silver and nickel mesh fabric from either side. The bag is "sealed" via a hook-and-loop fabric.

We did not have a new RFID passport on hand, but we were able to try the effectiveness of the bags with several cellphone models. We used the bags with a Blackberry 7520, a Sony-Ericsson k790a Cyber-Shot and a T-Mobile Sidekick II, which we placed into the inside pocket of the bag. We then sealed up the bag and called the phones - every call went to voicemail and the phone inside did not ring or vibrate. The phone worked just fine when used outside the bags.

The bag has printed instructions that advise people to place the passports inside the inner pocket. Our brief test revealed that the blocking of signals in fact requires users to put devices into the inner pocket. When placed into the bag, we were able to access the phones without difficulty. Our guess is that the signal can leak through the regular hook-and-loop fabric, if just the main pocket is used.

If the Stronghold bag can block RFID and cellular phone signals, there is the obvious question what other signals the bag could block as well? For example, could someone use the bags to block signals anti-shoplifting devices from retail stores? Paraben's Schroader was not able to provide an answer to this question, but said that "is scaled specifically for a passport and it is also not the most subtle thing in the world." Schroader believes that the shiny bag will stand out and "if it does work on those security devices, we've taken measures to mitigate the risk of it being used for that," he said

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New passport holder claims to block unwanted RFID signals