I have a stream that I want to encrypt for broadcast to 10,000 subscribers. I know I should encrypt this data using a symmetric key; and also intend that this symmetric key will be rotated every 30 days.
Assuming that I already have a Public key for each subscriber (private key only known to them), how should I encrypt the symmetric key and send it to the subscribers?
Or is this just obvious; I just encrypt the symmetric key with each public key? Are there any special considerations I need to take?
For example, how does the length of the symmetric key factor in to the solution? I am considering wrapping the symmetric key in a SOAP or JSON message which may alter the length of the final string to be encrypted.