NUT-16: Animated QR codes

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This document outlines how tokens should be displayed as QR codes for sending them between two wallets.

Introduction#

QR codes are a great way to send and receive Cashu tokens. Before a token can be shared as a QR code, it needs to be serialized (see NUT-00).

Static QR codes#

If the serialized token is not too large (i.e. includes less than or equal to 2 proofs) it can usually be shared as a static QR code. This might not be the case if the secret includes long scripts or the token has a long memo or mint URL.

Animated QR codes#

If a token is too large to be displayed as a single QR code, we use animated QR codes are based on the UR protocol. The sender produces an animated QR code from a serialized Cashu token. The receiver scans the animated QR code until the UR decoder is able to decode the token.

Resources#

• Blockchain commons UR
• Typescript library bc-ur