65

If you deface a credit card, you are likely to find it will be rejected for all transactions. The merchant really needs all the info on the card to be valid - it's part of how they protect themselves from fraud. So my answer would be: none! Instead of worrying about that, concern yourself more with how the merchants handle your card. In the UK, for example,...


51

I put a small sticker over the CVV to avoid it being casually seen. The CVV is the three-digit code on the back of the card beside the signature, needed when you buy things on the Internet but not otherwise. A merchant who takes your card and checks the signature can easily remember the three digits, and I think this was what happened the one time my credit ...


8

The better answer is to use Virtual Credit Cards. You can create a throwaway number with a transaction limit and time limit for dealing with each unknown vendor/merchant, you can also set an amount limit on recurring billings. Check what virtual CC setup either your CC vendor (Mastercard, Visa) or issuing bank (BoA, Citi) has. Check the amount of time to ...


6

A QR code is just text, encoded in a format that is easily readable to a computer. Can you make the preceding sentence uncopyable? You cannot make text incopyable. Forget it. It is utterly impossible. What stops me from whipping up paint.exe, and copying the QR code pixel by pixel? Or place it on a scanner and print thousand copies? QR codes relies on that ...


6

The way you phrase your question seems to indicate that you think it's a bad apple at a merchant who is stealing your credit card, namely by using a manual method of writing down card details. Let me tell you, that that is extremely unlikely. All of your card's basic information (name, account number, etc.) is embedded within chip data, as well as in the ...


4

My ISP (SFR, French one) also sell this option. It basically consists of a "security app" for Windows/Mac OS X/iOS/Android that implements antivirus, anti-malware, browser analysis, etc... It's more or less the equivalent of Avast, Kaspersky, etc... Since I wouldn't "buy bread from a butcher", I didn't buy the "security app" from SFR.


4

Yor credit card has the card number, expiration date, cardholder name, and possibly an additional short security code that you could conceivably remove from the physical card and store in a password safe. But all of these (except, I think, the additional security code) are needed by the merchant. So you can't tamper with any of them. Besides, the merchant ...


4

One standard method used for something like this is application layer encryption. Your project consists of a web tier (Django) and a database tier (PostgreSQL). If you implement your encryption in Django, then you can write encrypted blobs to the PostgreSQL data store. This is not, by the way, "client side encryption" as described in the article you link ...


3

The usual approach is to use a master key for each account that does the actual encryption/decryption/integrity check, but that is never stored in plain text anywhere. This master key should be generated using a secure random number generator and there should be no way to retrieve its plain-text value. You encrypt the master key with per-user keys derived ...


2

Typically the issuer does not provide such information to the acquirer/merchant. It will only provide information about the authorization of a transaction (ie accept / decline etc). It will, in specific circumstances if asked, confirm that the address provided by the customer matches the address held on record (the Address Verification Service or AVS) but ...


2

The two problems you are facing with NFC tags is either preventing a re-write of the tag by a malicious user, or the NFC tag being replaced by a malicious one in the advertisement. The first problem can be resolved by using read-only NFC tags. These cannot be reprogrammed and thus thwart any attempts to modify the NFC tag contents. The second issue is a ...


2

Anyone attempting to set up a "secure" home network with "smart" devices is going to have to make some compromises either about security or about ease of use. I would say the first thing to do is to segment your network into at least 2, possibly 3 or more. One for data access from reasonably protected End User Compute (EUC) devices (including desktops, ...


2

There are essentially two categories of answer to your question: blockchain as a better ledger, and blockchain combined with physically unclonable functions to do the things you seek. Blockchain As A Better Ledger Blockchain can function as a better public ledger system than existing paper-based or even traditional, single source, trusted electronic ...


1

How about a dedicated encryption service / demon running on your web server? The service would take a master password (known to you) and would need reentering on server reboot. You can the use a key derivation function to create an in memory encryption key. Data can be then be encrypted or decryted at will by the service which is consumed by the web app ...


1

While this makes some sense, I wouldn't do it myself. I presume you already have an internal home network with your laptops, desktops, tablets, internal NAS, etc. The normal way to setup at DMZ is that it's a separate network, with firewall rules that allow specific ports. So, if the MyCloud NAS uses port 443, you'd probably allow port 443 from the internet ...


Only top voted, non community-wiki answers of a minimum length are eligible