ahpnft/redmagicbox

RedMagicBox is an Android app for encrypting files and text using a layered combination of three cryptographic standards: AES-256-CBC for the actual encryption, PBKDF2-SHA256 with 100,000 iterations to derive the encryption key from a password, and HMAC-SHA256 to verify that an encrypted file has not been tampered with. AES-256-CBC is a widely recognized symmetric encryption algorithm, meaning the same key locks and unlocks the data. PBKDF2 is a key stretching function that makes brute force password guessing much slower by running the password through many iterations. HMAC-SHA256 adds an integrity check so the app can detect if an encrypted file has been modified. All encryption and decryption runs locally on the device, no data is sent to a server. Encrypted files are saved in a custom .red format, and the app lets a person choose a custom name for the encrypted file and optionally delete the original after encrypting it. The app can scan the device's storage to find all .red files, and includes features for decrypting, listing, and securely sharing them. Sharing copies the encrypted file to a temporary buffer without exposing the original file path, and can generate a share link paired with a QR code. To unlock unlimited encryption, the app uses a paid activation code system, priced in either USDT or the project's own RMAB token on the BEP-20 network. The activation code is generated via a blockchain smart contract and participates in the key derivation process, meaning that if the activation code is lost, files encrypted with it cannot be decrypted. The README states that the smart contract keeps each buyer's activation code private and readable only by that buyer, rather than broadcasting it publicly on chain. The README is written primarily in Traditional Chinese. The app is built with TypeScript alongside a native C++ encryption engine, requires specific Android storage permissions to scan and manage files, and targets Android 11 and above. It supports Traditional Chinese, Simplified Chinese, English, Japanese, and Korean interfaces, and the README includes a version history table documenting recent fixes to the activation code verification flow.