Cool. A few thoughts:

1. On the front page "Only you have the encryption key" could be confusing to folks new to PGP, consider instead "Only you have the decryption key". Then elaborate below - your encryption key/pubkey is uploaded to your service and made available to any users of your form, while your encryption/privkey remains secret.

2. What's your experience doing crypto in browser Javascript? I looked at that earlier this year but it was still pretty immature. Things like Mailvelope are a good start but not 100% reliable.