@jaywink @firstname.lastname@example.org @heluecht the way mastodon currently serializes it is also valid JSON-LD, although there ARE some subtle differences between the two. As I understand it, the array form is including the entire context while the object form is only referencing the namespace.
mastodon would not be able to process "sec:publicKey" currently, but I would prefer you federate the extension the way you prefer to and then open an issue to have us make our code compatible rather then the other way around.
the mastodon instance at cybre.space is retired
see the end-of-life plan for details: https://cybre.space/~chr/cybre-space-eol