Pros:

• SecureDrop does not record where things come from.
• All material is encrypted automatically.
• We read your submissions on secure computers.

Cons:

• You will need to download Tor software to access our SecureDrop system.
• If you are being watched, the very act of using Tor may arouse suspicion.

SecureDrop allows you to safely send us messages and documents, and to follow up with us later if you wish. All we get is what you send us plus a codename that allows us to reply to you. SecureDrop records nothing else about you. To prevent interception at our end, we decrypt any material that you send us on a system that is completely offline.

Get started:

On a computer that you are confident is not being monitored, install Tor Browser. Then go to theguardian.com/securedrop and follow the instructions there.

After that:

When you first visit our SecureDrop site itself, you will be given a passphrase before you can send anything. This phrase allows you to log back in to view replies from us and to continue correspondence, if you so wish. We do not always reply to messages and even when we do, responses can take several days.

SecureDrop is quite a slow way to communicate, so after you have begun corresponding with a reporter they may suggest a more direct way to interact. You don’t have to agree to this, of course, but it can make things smoother under some circumstances.

SecureDrop is an open source project managed by the Freedom of the Press Foundation.

Signal is trusted by journalists, human rights activists and security experts worldwide, and is our recommended instant messaging app. WhatsApp, while not quite as secure, also encrypts the content of communications and benefits from being so ubiquitous that using it is unlikely (in itself) to raise suspicion in most parts of the world. Other secure messenger apps tend to be less widely used for communication between sources and our journalists.

Pros:

• They’re very easy to use.
• They allow for speedy back-and-forth communication.
• Everything is encrypted in transit and on the service providers’ servers, so not even they can read the content of your messages.

Cons:

• On WhatsApp, information about the participants in a conversation is less secure than the content itself.
• There are ways for very sophisticated adversaries, such as government spy agencies, to ascertain that someone is communicating with a journalist using messaging apps – even if they can’t read the message content.
• Instant messenger communication requires advance knowledge of the participants’ contact details. For WhatsApp it must be a phone number; for Signal it can be a username or phone number. Many journalists are reluctant to publish their personal contact details widely because such information can be abused.

It’s not uncommon for conversations with journalists to shift to instant messenger apps once both sides have established some trust and have discussed the benefits and risks. But you or the journalist may decide not to use them.

Get started:

Decide whether you want to do this on your normal phone or if you want to buy a less easily traceable phone for this purpose. After installing the app, make it as secure as possible: if there are extra authentication options, activate them. And activate disappearing messages so your conversations don’t sit around forever on your device.

Read more about Signal here and about WhatsApp here.

After that:

If you’re worried about surveillance and you’ve not used the app before, consider using it for few innocuous purposes first, such as exchanging messages with friends. That way, when you message us, your use of the app doesn’t look out of the ordinary.

Signal/WhatsApp numbers for our investigations teams:

• United Kingdom: +44 7721 857348
• United States: +1 646 886 8761
• Australia: +61 490 758 250

Please don’t call or send ordinary text messages to those numbers. You won’t get a reply.

Check our journalists’ profile pages for other contact details. Google their name and “the Guardian” and you should find them. If you can’t find the right contact details for the journalist, you could message one of the above numbers and ask for your details to be passed on to the person you have in mind.

Please note the recommendations earlier in this guide for what to say about the information you wish to share.

If the information you wish to share with us isn’t extremely sensitive, email is probably the easiest way to get in touch. Even so, you may consider it worthwhile to put a bit of distance between your messages to a journalist and the rest of your life. Plus, because journalists receive so many emails, you should take extra care to make sure your message doesn’t get lost in the noise.

Pros:

• Everyone knows how to use email, and many Guardian journalists publish their email addresses.
• You can send long messages and attachments. This is difficult using phone apps.
• It's possible (but not straightforward) to add encryption to email messages.

Cons:

• Normal emails are not at all secure. Your correspondence can be monitored. Even a purpose-built email account can reveal information about you.
• Adding encryption to emails is difficult and does not hide some information (who is talking to whom, the subject lines, etc).

Email is an inherently insecure medium but you can do some things to make your correspondence less likely to be intercepted.

Get started:

Don’t use your regular work or personal email address. Create a new email account solely for corresponding with the Guardian. Do this on a computer that can't easily be linked back to you.

When you sign up for a new email account, make sure the sign-up information you provide doesn’t tie the account back to you. Never use the same password for different accounts.

After that:

Because it's so easy to send emails, journalists often receive a lot of spurious and irrelevant messages. So anything that doesn't get their attention quickly may be overlooked. Read the advice further up in this guide about what makes a good story tip.

Information carried with an email message can reveal your IP address. If you don’t want the location you send from to be traceable, connect to your email service over the Tor network. or send from somewhere that doesn’t easily identify you.

Remember to log out after sending the message. You may also wish to delete the history of the correspondence from your browser or email software. Keep your computer secure.

Some Guardian journalists publish PGP keys, allowing you to encrypt the content of email messages (but not the subject line or the fact that you are communicating with them). See theguardian.com/pgp.

Pros:

• Requires no technical prowess.
• Useful to initiate communication with a journalist to exchange contact information for more secure channels.

Cons:

• Telephone communication can be intercepted and could reveal your identity and/or location.
• It’s not always easy to verify that the person you’re speaking to is who they say they are.

Get started:

Before you get in touch, find the name of the journalist you want to speak to, and decide in advance exactly how much you want to tell them about who you are and how they can get back to you. The journalist you want may not be available when you call, so you may have to leave a message. Be prepared for that.

If you plan to share documents with us later, look at some of the other options in this guide before calling so you can tell the journalist how you’d prefer to do that.

Consider whether or not it is safe to call us from your work or home phone, or from any mobile phone that is associated with you. If you buy a pay-as-you-go sim card to call us from a new number, think carefully about where and when you buy it, and how you pay for it. And remember that mobile phone calls disclose the handset ID as well as the sim card.

After that:

Call us on one of these numbers:

• London office: +44 (0)20 3353 2000
• Sydney office: +61 (0)2 8076 8500
• New York office: +1 212 231 7762
• Washington office: +1 202 517 89042
• San Francisco office: +1 415 919 5874

Pros:

• If appropriate measures are taken, conventional mail can be a reasonably good way to hide who you are.
• If you don’t want to meet a journalist in person, it’s the only reliable way to hand over physical objects.

Cons:

• It’s slow.
• Post can get hijacked or at least scanned in transit.
• Post can get lost.

If you’re not actually being followed it’s fairly unlikely that an envelope or small package will get intercepted.

Get started:

Stuff can go missing in the post, so consider how bad it would be to lose the material you’re planning to send us. Can you make copies?

Think about whether or not you need to preserve your anonymity. Could the posting location give you up? How about the materials and packaging? If you’re very worried about the package being traced back to you, post it somewhere busy and make sure there is nothing memorable about your or the package’s appearance.

Mail is scanned for dangerous compounds and objects. Don’t include anything that could cause problems with delivery. International mail needs a customs declaration, and registered mail requires you to provide sender details.

After that:

• Guardian UK postal address:
  The Guardian
  Kings Place
  90 York Way
  London N1 9GU
  United Kingdom
• Guardian US postal address:
  The Guardian
  315 West 36th St
  New York
  NY 10018
  USA
• Guardian Australia postal address:
  The Guardian
  Level 2
  19 Foster St
  Surry Hills
  NSW 2010
  Australia