HTTPGetLogs is the path of the URL to get a list of all logs the witness is aware of.

HTTPGetSTH is the path of the URL to get an STH.

HTTPUpdate is the path of the URL to update to a new STH.

CosignedSTH has all the fields from a CT SignedTreeHead but adds a WitnessSigs field that holds the extra witness signatures.

UpdateRequest encodes the inputs to the witness Update function: a (raw) STH byte slice and a consistency proof (slice of slices).