I have argued this in the distant past and am glad it is getting attention, but we all need to worry about long-term recorded surveillance and the growing developments in machine learning. In the past, the majority of surveillance was recorded short-term and often examined in real-time for human operators to watch over larger areas easily. But we have quickly come to the point where long-term recording is getting cheap enough for indefinite storage. This might seem like a bad thing in itself but made even worse with the fact machine learning also improving to the point where processing hours of the recordings is easily possible with automated software.
This combination means that anyone could in theory be charged with a "recorded crime", meaning that law enforcement did not notice your crime in real-time and no one filed a crime against you but later follow up systems/software found the infraction. At first these systems will probably only be used to help existing investigations but no doubt it will be used later in much the same way as red-light and speeding cameras trying to generate revenue for municipalities.
Should this be allowed in our society? Where do we draw the line?
Secondly, the integrity of the recordings should be paramount. Your idea for encryption is a good one, perhaps expanding it to breaking down the recordings on a 10-15 minute basis with an individual key and checksum for each.
I mention a checksum because we are already at the point where computer generated imagery (CGI) has photo-realism and it could be possible for someone to easily plant images into these streams, allowing the changing of faces, clothing, etc. Body cam footage need to be handled as a chain of evidence and their recordings must be kept secure while also well documented against manipulation.
Law makers need to address this issue now, otherwise this will create a kind of police state that even makes the world of 1984 look like utopia.