I’m using RFID-protection-sleeves made of cryptalloy for my contactless-cards; they shield good against unwanted scanning, but they also make it hard to take the cards out (yeah I’m a bit clumsy)
I bought myself some cheap RFID-shieldcases from “overseas” (probably simple alluminium, but also shielding). Of course, those things have a very small “grip-area” for the cards, too.
I now had the idea of “cutting the sleeves out a bit”, so i can easily grab the cards. But I don’t know how much i can cut out without negating the shielding, as I have no idea where the RFID-Antennae in the cards are…
Is there a certain area that should be covered? Or do the antennae (not only revolut cards) go over the whole area of the cards?
BTW: it would be great if Revolut would ship the cards with RFID-shielding sleeves - the Chaos Computer Club demonstrated over a decade ago how easy those things can be spoofed and “sniffed out”… And those sleeves aren’t THAT expensive
yeah i think JoyM is right, i just checked several cards with my (nfc enabled) cellphone by covering up spaces. some cards are close to the chip, others have a wider area…
question’s now “how much exposure is needed to negate the shielding” - eventough the oversea-sleeves were/are cheap, i don’t wanna risk them all by “testcutting” too much out…
thanks for the screenshot - interesting layout (and the transparent card is looking cool, too
seems there’s no way to cut on one of the sides without exposing the antennae…
does anybody know how much of the antennae-length’s needed to induce enough current for the chip to start working? (and making a good signal)
I want to adjust the sleeves (i bought), not the card (i like the contactless payments, just not “out of the pocket”, so to speak) - but yeah, with RFID it’s more a coil then an antennae… The question remains the same though, “how much can be exposed without the chip “starts working”?”
I did it - and cut one of the sleeves (hope the img-upload works the way i hope); I just cut the frontside so I can give my thumb a good “grip”, while my finger grabs the opening (front and back are symetrical, refer to the sleeve with the green card in it). So I now have an approx 2cm-opening in the front, and the “old” cut in the back - it’s much easier to get the cards out now… (Edit: and the sleeves still shield form reading the card with cellphone**)
(** BTW - these sleeves from “overseas” (china are made of a thicker paper (my guess 140g/m² - just a bit thinner than the old “photopapers” for inkjet-printers) and some alluminum-coating on the inside, not very thick. They shield the signal when using a cellphone, not sure how well they work with some “shop-grade” hardware - will test and report results. (at least the cryptalloy-sleeves are completly made of that “alloy”, the protection sure is bigger than those cheap ones)