If you're looking for an ephemeral video sharing app, limiting the recipients to two people who must both consent to viewing the recorded video, iOS-exclusive app Rumuki fits the bill.
The app's website beats around the bush somewhat about what it's intended for now, but Product Hunt is less circumspect, calling it a "prenup" for "home videos." Regardless of the reason you want to use it, the app functions very simply.
The videos are entirely contained within the app, and never see the iOS camera roll. You and a recipient download the app, and link to each other's accounts. During the video shoot, audio is encoded with AAC with video encoded by MPEG-4 AVC, with encryption performed on-the-fly during the shoot.
Metadata from the shoot is never sent to the Rumuki key servers including video names, nor are the videos themselves uploaded to any server.
The recorded video can't be viewed on either device unless both parties consent to viewing, following a request by one viewer for a playback.
Users of the app can set restrictions on the video, such as how many times it can be viewed, expiration dates, and the like. Additionally, either party can choose at any time to delete the video, at which point it is stricken from both linked apps.
At present, only video is supported. Photos may be added at some point in the future.
Initial AppleInsider testing of the app initially manifested some encryption key exchange issues, but over the course of testing, they resolved themselves. By definition, an app that exchanges encryption keys over the internet demands a persistent connection, and it may not function properly or at all in low connectivity areas.
Performance-wise, on an iPhone 7 Plus and iPhone SE, the encryption does in fact happen in real-time. On an older iPhone 5s, there was a slight delay after a video was completed and just before playback where the app appeared to hang for a few seconds.
The developer has a notification button for an Android version, but it is unclear when or if it will arrive. At some point in the future, the Rumuki developers will open-source the components used to build the app.
The developer, Nathan Kot, says that the app isn't a foolproof prevention of video leaks.
"You can't prevent someone from [using] a [separate] video camera," Kot told CNN in an interview in February. "If you want to be 100 percent safe, you should just not take any videos at all."
Rumuki requires iOS 10.0 or later, and occupies 68.9MB of storage space -- which expands and contracts as videos are stored and deleted. The app is temporarily free.