A QR code, or Quick Response Code, is a two-dimensional machine-readable barcode that can be used to represent an address. The use of a QR code makes it easy to scan an address, rather than having to type or copy it.
Using QR code addresses in Trezor Wallet
The Trezor Wallet shows receiving wallet addresses as QR codes, so they can be easily scanned from a mobile device or using another camera. If given access to a camera, the Trezor Wallet can also scan QR codes of an address to send funds to.
See also: Address (basic)
Why to use a QR code
When using Bitcoin or other cryptocurrencies to pay at the point-of-sale or for a face-to-face transaction, there is the problem of how to communicate the receiving address in a way that the person paying can use. A Bitcoin address is between 27 and 34 characters long. This takes time to type manually and it is easy to make a mistake.
On the other hand, a QR code can easily and reliably represent this amount of data in a machine-readable manner. The QR code can (potentially) contain other information as well, such as an amount and a message.
With a mobile phone, a convenient way to pass that data is for the payment recipient (e.g., a merchant) to display a QR code with the Bitcoin address for the transaction, and then for the person paying to scan that code to obtain the address.
It is also possible to print out the QR code containing the user's receiving address and hand it to the sender, who can use it for repeated or regular payments.
How does a QR code work
As mentioned above, a QR code is a two-dimensional barcode that contains machine-readable information in a convenient manner. It was first designed in 1994 for the automotive industry in Japan and has since expanded to a wide range of applications. Where a traditional barcode presents a string of information as a one-dimensional line of black and white bars, a two-dimensional barcode packs significantly more information into a grid of black and white squares.
It contains the following information:
- Quiet zone: Empty white border making it possible to identify the code among other printed information.
- Finder patterns: Larger black and white squares in three of the corners. They differentiate QR codes from other types of barcodes and make the orientation of the code clear.
- Alignment pattern: Ensures the code can be deciphered even if the code is distorted.
- Timing pattern: Makes it easy to identify the individual data cells within a QR code and is especially useful when the code is damaged or distorted.
- Version information: Identifies the specific standard of the QR code.
- Data cells: Contain some of the actual data in the code.