RSA Excel Encryption Tool

I need a Windows-based utility that can take any .xlsx file I feed it, lock it with my public RSA key, and later unlock it with the matching private key, returning the spreadsheet bit-for-bit identical to the original—including formulas, cell formats, charts, embedded objects, and full-width Unicode text. Core requirements • RSA 2048-bit (or higher) encryption implemented end-to-end. • Key-pair generation built into the tool so I can create, export, and back up keys without touching OpenSSL by hand. • Public-key encryption, private-key decryption workflow; no symmetric fallback. • Zero data loss: after decryption the SHA-256 hash of the file must match the pre-encryption hash. • Runs locally on Windows 10/11 with no external dependencies that aren’t freely redistributable. Deliverables 1. Compiled executable with a simple, intuitive workflow I can hand to non-technical teammates. 2. Complete, well-commented source code. 3. Step-by-step setup/build instructions so I can reproduce the build on another machine. 4. A short usage guide covering key generation, encryption, and decryption. Acceptance test I will encrypt a multi-sheet workbook containing formulas, conditional formatting, pivot tables, and UTF-8/UTF-16 characters, then decrypt it and verify the original and restored files are byte-identical and open cleanly in Excel. If the hashes match and Excel shows no corruption warnings, the job is done. Choose the implementation language and UI style you’re most comfortable with; clarity, security best practices, and rock-solid file fidelity matter more to me than the tech stack.