Salt which is 32 randomly generated bytes is used to derive keys
Ciphertext is produced using
AES-256-CBC with key
EKey and a random 16-byte iv
Hmac is produced using
HMAC-256 with key
This is encoded as the following.
My question is, can I RSA encrypt key
K and append it to the encoded string such that it remains secure?
I'm not entirely sure how to respond to Rory's comment, so I'll give my best shot.
By secure, I mean being able to transport this payload over the wire without having a third-party (without the corresponding private RSA key) able to decrypt or mutate the payload.
This approach may also be used for data at rest.