Server side encryption is handled using the Go standard library. A more detailed breakdown of the process can be found in the Help Center. TLDR: It's reputable, and best practices are followed through cryptographically secure generation, random IV, high entropy keys, memory hard hashing, etc.
Paste end to end encryption uses the native window crypto subtle API, widely used and reputable.
Coming from cyber security one thing I have learnt is no matter how many layers of security you add nothing is fool proof, I would strongly recommend doing an Independent review getting if not an international certification like ISO or GDPR then something domestic, I like what Mozilla does https://www.mozilla.org/en-US/security/advisories/, this really will enforce trust in your users as today it's really hard to trust websites
Paste end to end encryption uses the native window crypto subtle API, widely used and reputable.