On Friday, hundreds of thousands of people will arrive in downtown Washington for the inauguration of Donald Trump. Many will be there to celebrate the incoming president, but a significant number will also be there to signal opposition, as part of the Women’s March and other demonstrations. Given the incoming President’s reliance on private security forces distinct from the Secret Service, it’s unclear how authorities will respond to the protests. If you’re planning on attending the protests or others of this kind, here are some steps you can take to protect yourself and ensure anything you record during the event is as secure as possible.

Protecting your data

The likeliest threat is also the simplest one: you’re detained and police search your devices for any evidence of a crime. Given that the crime could be as simple as venturing outside the designated protest areas, that’s a potentially frightening scenario, and good reason to make sure no one can look at your photos and other data without permission.

That means making sure all of your devices are disk-encrypted. That’s standard on iPhones and can be turned on in almost all Android phones under Settings > Security > Encrypt Device. Android users will want to start this process the night before, since it takes a while and the phone needs to be plugged in the whole time. There are ways to make this encryption stronger — setting a longer password, for instance, or upgrading your Android version — but for most quick detention scenarios, the important thing is simply making sure there’s a lockscreen police can’t immediately get past.

You’ll also want to disable fingerprint logins, in case police force your finger onto the phone to break through the lock screen. That’s not standard procedure for most police, and it’s not entirely clear whether it’s legal. (The Minnesota Court of Appeals upheld legality earlier this week, although the debate is ongoing.) As long as your goal is staying out of a courtroom, it’s better to disable fingerprint logins up front. Both iOS and Android make it easy to do from the settings menu.

The bigger concern is that police will grab your phone while it’s still unlocked, an increasingly common practice among encryption-savvy law enforcement agents. As a result, many experts recommend recording from outside the lock screen. iPhone users can access that by swiping left, but Android users will have to enable it in Settings > Display, then press the power button twice to access. In each case, police will have immediate access to the most recent entries in the camera roll, but nothing beyond the last time your phone went to sleep.

Those concerns are also a good reason to leave your DSLR at home. Most conventional cameras still don’t have any protections of this kind, so any picture you take will be fair game for police searches.

Preserving a broadcast

Phones aren’t just vulnerabilities; they’re also powerful tools for documenting and sharing events. So once you’ve made sure your device can’t be used against you, you can turn your attention to making sure that what you’ve seen gets documented, distributed, and preserved. Black Lives Matter has shown how powerful protest footage can be in shaping public debate, particularly when it’s shared on platforms like Facebook and Twitter. 

The biggest problem is the platforms themselves. Moderation is inconsistent at best, and if platforms have reason to believe a crime has been committed as part of a video, they usually won’t hesitate in taking it down. That will prevent footage from spreading, but it can also effectively erase the only record of events, particularly if the footage was being livestreamed. As a result, Witness recommends saving local version of all the footage you take, which is available as an option for both Periscope and Facebook live.

The work of preservation can also be done by people following the protest online. If you’re concerned a video might be taken down, you can preserve a local copy using archiving tools like VideoVault, YouTubeDL or WebRecorder. Each service has its strengths and weaknesses, so pick what’s right for you, but the end result is the same: a local hard copy of the video you just saw, which can be preserved even if platforms remove the original.

In more practical terms, the biggest threat to your ability to film is probably your phone running out of power. Veteran protest reporter Quinn Norton recommends keeping a spare battery pack handy for just this reason. Even if you don’t need it, it’s likely that at least one person in your group will.

Avoiding direct surveillance

There’s a long history of surveilling protests, particularly with Stingray devices, so you may want to take precautions to make sure no one can listen in on your conversations during the event. It’s easy to intercept SMS text messages, and while iMessage is internally secure, all it takes is a single Android device to kick the entire thread back to SMS. As a result, you’re better off talking on Signal or WhatsApp where your conversations can’t be read by a third-party surveilling the network.

Beyond that, there’s the question of how to prevent authorities from identifying you personally. it’s difficult to entirely protect against this, but there are a few measures that will make it more difficult. The first is to use your cellphone’s various antennae as little as possible, putting your phone in Airplane Mode whenever you’re not actively using it. Reflective sunglasses will stymie many facial recognition systems, although not all, and the overall effect is less reliable.

In some ways, this is still an abstract threat. In practical terms, many protesters are registered as attendees through a specific group, which means you’ve already willingly given your name as part of the larger political statement of the action. More broadly, political dissent is not a crime, and part of the purpose of protest is to register opposition as a citizen, a goal that can sometimes be undermined by anonymity.

If you’re curious to read more, there are excellent guides available from the Electronic Frontier Foundation, Access Now, and Freedom of the Press, all of which are very much worth your time.