In this guide, we’ll explore how to implement a Public Key Management System for signing QR codes, focusing on the QCAT Signature Algorithms Version 1 and 2. Key Management Overview The QR Code signature system relies on cryptographic keys and certificates to ensure the authenticity of the QR codes generated by issuers. The key players in this system are the Certificate Authority (CA) and the QR Code Ticket Issuers. 1. Certificate Authority (CA) : The CA signs the issuer’s public keys using its private key, creating a public key certificate. This certificate ensures the QR codes can be verified at validation terminals. CA uses a 2048-bit RSA key to sign the issuer’s keys, ensuring a high level of security. 2. Ticket Issuer : Each issuer generates their own public/private key pairs. The private key is used to sign QR codes, while the public key is included in the certificate signed by the CA. Validation terminals use the issuer’s public key to verify the signature on a QR code. 3. Valid...