Javascript Encrypted File Upload (C# server-side)

Functionality is needed for an existing ASP.NET web forms application to upload/download files that are encrypted/decrypted in the browser with JavaScript prior to uploading to the server. A form should be built that includes a file upload component that allows multiple files, unlimited file size, and has a progress bar. The component should use AES and accept a password which is used to create the key (must use a strong PBKDF). Other details regarding cryptography and security details will be discussed later. The selected Freelancer must have strong JavaScript skills as well as security knowledge (e.g. cryptographic standards).