Update the Upload and Download flows

[fforbeck]

Upload

• Generate a symmetric key on the client and use it to encrypt the file
• Encrypt the symmetric key using the public key for asymmetric decryption
• upload encrypted content (encrypted file + encrypted symmetric key) -- ideally keep it as close as possible to feat: add spec to describe space/content/decrypt ability specs#132 -- let's iterate on the spec so it's compatible between networks (won't be implemented at this stage)
• Security Audit with AI Models
• Fix encoding issues
• Store file metadata as part of the encrypted content

Download

• Fetch encrypted content from regular storacha.link
• Send encrypted symmetric key to private.storacha.link with UCAN proving access to space, which will be used to auth using KMS key to decrypt symmetric key and send in response
• Use the decrypted symmetric key to decrypt file
• Security Audit with AI Models
• Fix encoding issues
• Read file metadata to provide proper file name and type for download

[fforbeck]

Done