Jacob's RSA Implementation Running on Web Assembly

This is a version of my RSA Implementation with OAEP running entirely client-side* in your browser with Web Assembly! It runs slowly (and generating large keys is impractical) due to the limitations of WASM, but if you'd like to use high-speed versions of my code, please feel free to clone, compile, and run either the "multithreaded" or "max-speed" branches of my code (not the "emscripten" branch running here in your browser's virtual machine).

* The project only runs client-side-only if you use none of the recently-added server-side functionality. See here for more info.

Note: Generating keys here is somewhat less secure than cloning, compiling, and running my machine-code (non-emscripten) branches from GitHub.

WHY: Because Web Assembly's wasi-random has not yet been implemented nor standardized, I am forced (on the web version only) to use a pseudorandom number generation method that is only semi-cryptographically secure.

The Good News:

• If you just want to play around with this RSA Implementation (which is probably the best idea), everything works fine!
• You can upload keys generated from the standalone program to this website! Just add "WEB" to your store command as described in help

New Server-Side Functionality

Securely Store Your Text Across Devices

I've introduced a new encryption feature for securely storing text on the server, accessible from any device with your private key. Here's how it works:

1. Firstly, your browser must prove to the server that it has the private key associated with your public key.
• Your browser will use your private key to sign a message consisting of a nonce ("random number used one"), a timestamp, and your public key.
• Then, your browser encrypts that signed message with my server's public key (cached on your first visit) and sends it off.
• If my server verifies that you have the private key associated with your public key, my server will authenticate your session for a short period, which you can end early by closing your browser.
2. Now authenticated, your browser can upload text to store via a similar process.
• Your browser will sign your encrypted text and send it to my server, encrypted again with the server's public key.
• If my server can verify (using RSA message validation) that the text came from the owner of a private key whose session was previously authenticated, your ciphertext (and only your ciphertext) will be stored on my server.
3. Downloading Stored Data
• When you click "Sync Public-Key With Server and Fetch Ciphertexts," your browser will rerun step 1 to authenticate with the server and will then receive all your stored ciphertexts.
• Once your browser decrypts those stored ciphertexts with your private key, they will appear at the bottom of the page.