Signal does encrypted messages and phone calls between Signal users. It runs on Android, iPhones and iPads.

Amongst techies, Signal is well regarded for security and encryption. It fails, however, on anonymity, something no one cared about for years and years. Beats me why. Signal is worshiped like a religion despite using phone numbers as userids. It can be critically important to hide who you communicate with and Signal does not do this. This strikes mes as a classic nerd mistake, to focus on technology (encryption in this case) and ignore the human need to be anonymous.

How to: Use Signal from the EFF. Long and detailed. A must read. Last Reviewed: March 6, 2024.

The fewer messages on your device the better. To that end, see these two support articles from Signal Set and manage disappearing messages (undated) and Delete messages, alerts, or chats (undated)

July 12, 2024: A bad look for Signal. Signal encryption key vulnerability being fixed on Mac (and less fully on Windows) by Ben Lovejoy for 9 To 5 Mac. Both the Signal macOS and Windows apps are not using great security. The encryption key for locally stored messages is stored on the machine in a plain text. Security researchers have been pointing to this vulnerability for at least six years. They had to be shamed into fixing this.

November 8, 2023: Can you teach an old dog news tricks? Signal tests usernames that keep your phone number private by Sergiu Gatlan for Bleeping Computer. Yes and No, seems to be the answer. Signal has a setup an all new test environment for supporting usernames. However, you have to sign up for a new account in their test environment using a phone number and the option to hide your phone number is OFF by default. The feature seems to be a long way off.

I don’t trust Signal by Jan Harasym (June 18, 2020). The author makes a lot of very good arguments. Perhaps the most striking to me was about open source software. Yes, Signal is open source ... in some respects. But not in all respects and probably not the way people assume. Of course, there is the issue of phone numbers. He also points out that the way Signal encrypts your contact list is poor. And, he makes the same observation that I do, that support for Signal seems like a cult. His term is that there is too much support for it. We saw nerd cult behavior with OpenVPN which was the greatest flavor of VPN ... until WireGuard came out, at which point we finally started to hear bad things about OpenVPN. Quoting the blog: "... I am not saying Signal does anything bad, I am really just saying that they could do harm; and the only thing that says they won't is 'trust me' ... I don't think any individual issue I’ve mentioned here is a dealbreaker, and most in isolation can be argued away. For me, though, in the larger context ... I can't really say that I have full faith in Signal. It's fine for me as an insecure messenger, but the user experience is just worse than other insecure messengers. I don't personally have any reason to trust it more than Telegram; other than that people get mad when you say that. Which, is incredibly unconvincing."

This Oct. 2021 blog by Yael Grauer How To Use Signal Without Giving Out Your Phone Number Using a Chromebook and an Old Phone points out many of the problems with the Signal app. Her solution is ridiculous and it too shows why Signal is a poor choice. Others have written the same article: Using Signal Without Giving Your Phone Number by Martin Shelton on Medium (Sept 2017) and How to Use Signal Without Giving Out Your Phone Number: A Gendered Security Issue by Jillian York for Vice (Aug 2017) and How to use Signal without giving out your phone number by Micah Lee for The Intercept (Sept 2017). All these articles are about hiding your main phone number. That is not the same as being anonymous. Not at all.

Other problems with Signal: you can not put the same account on two phones so all your eggs are in one basket, it supports disappearing messages but this has to be configured separately for each person you communicate with and there is no access to the service through a web browser.

If you do use Signal, there are quite a few dos and don'ts. This May 2017 article by Micah Lee is a good guide: How to keep your chats truly private with Signal.

This article, by Vladimir Katalov of Elcomsoft, shows the security is not perfect: How to Extract and Decrypt Signal Conversation History from the iPhone. The article is from August 2019, perhaps things have changed? I don't know.

You are probably safer in you disable the option to generate a link preview in the settings under chats.

FYI: Two Signal accounts on one device: There is an Android app called Molly that is a fork of Signal. On the September 16, 2022 episode of his Privacy, Security & OSINT podcast, Michael Bazzell discussed how he uses it so that there can be two different signal accounts on the same Android device. Molly is not in the Play Store and even installing it from F-Droid is not standard. On Linux, he uses SNAP to have multiple copies of Signal and multiple interdependent Signal accounts on the same copy of Linux. On macOS, the regular and Beta copies of Signal are separate, so installing each lets you have two Signal accounts on a single copy of macOS.

In August 2022, Twilio was hacked and Signal depends on Twilio to validate phone numbers. See their account: Twilio Incident: What Signal Users Need to Know of the incident. Phone numbers of roughly 1,900 Signal users were exposed to the Twilio breach attacker, who could have attempted to register them to another device. One solution is to on a Signal PIN and enable Register Lock. I read the doc and have no idea what this is or does. I have to wonder if Signal is too big and complicated for non techies to use safely. As for a checklist, in Signal do: Settings -> Account -> Registration Lock and verify that it is enabled.

In October 2022, Graphene OS tweeted about why they do not include Signal in their operating system (a clone of Android without anything from Google included). On a technical level, their points are over my head, except for the fact that Signal is dropping support for SMS/MMS. Even without fully understanding it, they make the point that Signal is far from perfect. Quoting "Signal is now dropping support for SMS/MMS. They also don't care much about keeping their dependencies patched, reducing attack surface or internal sandboxing. It would be an issue for GrapheneOS ... They've made many decisions we disagree with including replacing registration lock PIN with a sync PIN, depending on SGX for security, using SGX as a replacement for the previous private contact discovery and making the secure local backup system in the Android app less useful."

Finally, the Signal website is miserable to useless for a newbie to the software. I see this sort of thing all the time, experts can not understand the perspective of someone new to the subject. When experts write documentation, we get a cheat sheet for experts. We do not get anything that helps a newbie get up to speed.

INTRO: WhatsApp is owned by Facebook which should never be trusted. WhatsApp messages are end-to-end encrypted by default. So too are phone calls between WhatsApp users. It supports disappearing chats.

Your WhatsApp userid is your cell phone number. The service is unusable without a functioning mobile number, and you cannot hide your number from your WhatsApp contacts. If you swap the SIM card on your phone, and thus start using a new number, will have to change the number associated with your WhatsApp account.

To limit who can add you to groups and who can see information, such as your status and personal information, go to Settings -> Account -> Privacy

How to: Use WhatsApp from EFF. Long and detailed. A must read. Last Reviewed: Nov 15, 2023.

October 22, 2024: IPLS: Privacy-preserving storage for your WhatsApp contacts by Slavik Krassovsky, Kevin Lewi, Dillon George, Cheng Tian, Ercan Ozturk of Facebook. WhatsApp has lacked the ability to store your contact list in a way that can be easily and automatically restored in the event you lose it. They now have a new encrypted storage system called Identity Proof Linked Storage (IPLS) that lets users save their contacts and automatically restore them through WhatsApp. Users can create contacts directly within WhatsApp and choose to sync them to your phone or securely save them only to WhatsApp. They don't say if everyone gets this or if you have to turn on an option. They also don't say when it was/will be released.

Locked chats

1. v1: In the first draft of the locked chats feature, you were able to lock a chat using the same thing that unlocked the phone (pin code, fingerprint, etc). Introduced around May 2023, the Chat Lock feature creates a new folder. More here WhatsApp now lets you lock chats with a password or fingerprint by Sergiu Gatlan for Bleeping Computer.
2. v2: In December 2023, this feature was made more secure with a new Secret Code feature that allows you to further hide locked chats behind a custom password. Anyone who cares about security will use a password here that they do not used anywhere else. Locked chats with a Secret Code can then only be discovered by typing the secret code in the search bar. This prevents people who have access to your phone from even knowing that there is a locked chats folder. More here WhatsApp's new Secret Code feature hides your locked chats by Sergiu Gatlan for Bleeping Computer. The WhatsApp doc is here: How to turn on chat lock. Of course, it is undated.

November 8, 2023: Enhancing the security of WhatsApp calls by Daniel Sommermann, Sebastian Messmer, Attaullah Baig of Facebook. Two new optional features make calling on WhatsApp more secure.

1. "Silence Unknown Callers" quiets annoying calls and blocks sophisticated cyber attacks. With this enabled, calls from unknown numbers do not ring your phone. More.
2. "Protect IP Address in Calls" helps hide your location. Initial rollout began in October 2023. The feature causes calls to be relayed through WhatsApp Servers.

October 2023: Getting bad vibes from a group? Here are 3 options

1. Mute notifications for a group. You can resume notifications later. How to mute or unmute group notifications
2. Block individuals in the group chat or report material to WhatsApp if you believe it is inappropriately violent or BS. How to block and report contacts
3. Leave a group. Only the administrators of that group chat are notified. How to exit a group

June 2023: Best WhatsApp alternatives for privacy by Douglas Crawford of Proton. This article exists because WhatsApp changed its privacy policy in 2021, and it now shares its users' metadata and transactional data with Facebook/Meta.

April 13, 2023: A blog from WhatsApp about three upcoming security features: New Security Features: Account Protect, Device Verification, Automatic Security Codes. End-to-end encryption alone is not enough to protect you from account hijacking, device malware, or impersonation.

1. Account Protect: When you move your WhatsApp account to a new device, they will double check that it’s really you.
2. Device Verification: Malware can use WhatsApp to send unwanted messages. To help prevent this, they have added checks to authenticate your account. You do not need to do anything to get this feature. More: Device Verification
3. Automatic Security Codes: The security code verification feature helps to ensure that you are actually communicating with the person you think you are. You can check this manually by going to the encryption tab under a contact's info. Too hard? OK, they will make this easier with a new feature that allows you to automatically verify that you have a secure connection. What a secure connection means, they don't say in the blog. It surely has nothing to do with verifying the person on the other end. With the new feature, click on the encryption tab and you will be able to verify that your personal conversation is secured. More: Key Transparancy

January 19, 2023: Whatsapp accounts are being hacked using the phone number. If the voicemail system for your Whatsapp phone number uses a default pin code, you are at risk. This from a twitter thread by @ihackbanme. In brief:
  You're sleeping. A bad guy tries to login to your account via WhatsApp.
  You get a text message with a pincode
  The attacker clicks on the option that the SMS didn't arrive and asks for a verification by phone.
  WhatsApp calls you. You're sleeping. It goes to Voicemail.
  The voicemail stores the automated voice with the pincode
  The attackers check your voicemail by trying the default pincode which may be the last four digits of your cellphone number
  Then they can log in to YOUR WhatsApp.
  After getting in, bad guys setup a 2FA pincode that prevents you from logging back in

November 26, 2022: WhatsApp data leak: 500 million user records for sale by Jurgita Lapienytė for Cybernews. Someone is selling up-to-date mobile phone numbers of nearly 500 million WhatsApp users. A data sample investigated by Cybernews likely confirms this to be true. It is not known how the data was obtained. Defenses that I read about:
 --Beware of unknown numbers trying to message you or call you on WhatsApp
 --If you get a message from an unknown WhatsApp number, block the number and do not click on any links in the message
 --Configuration suggestions: Settings -> Privacy. Change "last seen and online" and "profile photo" and "about" to "contacts only"

How to Use WhatsApp Privacy Settings by Yael Grauer for Consumer Reports. Published January 8, 2021. Last Updated August 16, 2022.
Despite the end-to-end message encryption ... "when you use the app, you may be sharing more information than you realize with your contacts, anyone else with your phone number, and parent company Meta, which also owns Facebook and Instagram." Very long article. Some of the topics covered:

• Stop People From Knowing if You’re Online
• Hide Your Profile Photo
• Hide Your 'About' Information
• Don't Get Added to Random Group Chats
• Turn Off Your Live Location in Chat
• Restrict Access to Your Status Updates
• Block People You Don’t Want to Hear From
• Turn Off Read Receipts for Personal Chats
• Make Your Messages Disappear
• Set Up Disappearing Messages by Default
• Delete Sent Messages
• Send Photos and Videos That Can Be Viewed Only Once
• and more...

WhatsApp can make encrypted backups. However, as of December 2024, WhatsApp backups are not end-to-end encrypted by default. In other words, backups are stored in plain text (aka clear text) in the cloud. See this feature description from WhatsApp: About end-to-end encrypted backup (undated). Better yet, have WhatsApp message backups turned off.

From I Accidentally Hacked a Peruvian Crime Ring by Albert Fox Cahn for Wired (Dec 2021). The article makes a strong case for securing an account with an optional PIN or two factor authentication. And, despite the WhatsApp end-to-end encryption, Facebook knows who your contacts are, what groups you belong to, and when and to whom you send messages. Quoting: "With a simple subpoena ... they can get much of your account information. With a full warrant, the platforms can provide records on every aspect of your digital network (apart from the message itself). They can record who we communicate with, how often, the groups we're part of, and the identity of every member, along with your full contacts list. Even worse, WhatsApp can do this in nearly real time, transforming a 'privacy-protective platform' into a government tracking tool."

September 2022: WhatsApp will soon let users hide their online status from their friends. From: Some lucky WhatsApp users can now hide their online status by Chandraveer Mathur for Android Police.

Private WhatsApp groups are not very private. See Google Is Letting People Find Invites to Some Private WhatsApp Groups by Joseph Cox of Vice (Feb 2020)

How to minimise targeted ads on social media: WhatsApp from Privacy International (May 2019)

Upgrading WhatsApp Security by Martin Shelton on Medium (Feb. 2017)

You are safer when WhatsApp does not automatically download stuff (pictures, audio, video, documents) because you never know if the file is malicious. To prevent automatic downloads:

1. iPhone: Configuring auto-download from WhatsApp. By default, it automatically downloads images over a cellular connection. Audio and video will automatically download on Wi-Fi. To change this: WhatsApp -> Settings -> Data and Storage Usage. Tap on photos, audio, videos and documents and choose Never, Wi-Fi, or Wi-Fi and Cellular.
2. Android: Configuring auto-download from WhatsApp. By default, it automatically downloads images over your cellular connection. Other types of files? Doesn't say. To configure: WhatsApp -> More options -> Settings -> Data and storage usage -> Media auto-download. There is no Never option, instead you have uncheck a bunch of checkboxes as per the video.

Articles from WhatsApp about Privacy and Security. None are dated.

1. Privacy good starting point
2. About two-step verification
3. Account security tips
4. About end-to-end encrypted backup
5. About end-to-end encryption

From my research, Threema seems to be the best encrypted communication app. Steve Gibson, of the Security Now podcast, prefers it. The Mozilla foundation gave Threema an excellent rating on their Privacy Not Included website where they considered it a Best Of product. Sven Taylor of Restore Privacy also liked it. The app is developed in Switzerland, and has more than 10 million users, including the Swiss government and the Swiss army. It has passed two independent security audits.

Threema does text and voice messages, voice and video calls, groups, distribution lists and file sharing. Users are identified in the system with a randomly generated 8-digit Threema ID. Users must create a username and password to log into the app. Optionally, users can link their Threema account to an email address or a phone number and give it access to their contacts. Again, this is optional. The mobile app costs $5 in the US, a one-time charge. There is a version for Windows, macOS and Linux, but the mobile app is still required. There is also a web interface, but it too requires the mobile app.

January 10, 2023. Messenger billed as better than Signal is riddled with vulnerabilities by Dan Goodin for Ars Technica. Academic researchers examined Threema and found 7 vulnerabilities. They privately told Threema about this and some/most of the problems were fixed. Is secure enough in January 2023? I don't know, I need to find an independent expert. Quoting: "Matteo Scarlata and Kien Tuong Truong, two of the ETH researchers who co-authored the paper, said that all the flaws stem from a single trait: the use of a custom protocol rather than an established one that has stood the test of time." The researchers also said "... that a company whose main product is based on cryptography, should always have a cryptographer at hand to assess its security and to propose already-existing protocols when possible, for example the battle-tested TLS instead of creating their bespoke client-to-server protocol". In Threema's response they claimed the bugs were in an old outdated protocol. They failed to say that it was only old because it was revised based on this recent research.

From the Privacy Not Included website of Mozilla: Threema Reviewed on Sept. 8, 2021. Quoting: "Threema is one of the best privacy-focused messaging apps we have seen, with its end-to-end encryption, no phone number required to sign up, and its commitment to not collect user data. "

TLDR: Session seems to be better than Signal. Both are free and open source. Both use the Signal protocol for encryption.

Session has a lot going for it. It is an end-to-end encrypted messenger designed for absolute privacy. Quoting their website "Session is a decentralized messenger that supports completely private, secure, and anonymous communications." It does one-on-one real-time messaging and, like email, you can also send someone a message when they are off-line. It does open and closed group chats, voice calls and file transfers. No personal information is required to create a userid in the Session world (this used to be called a Session ID, now it is an Account ID). Session uses the Signal protocol for its encryption, but unlike Signal, it does not require a mobile phone number. Session is open source and minimizes metadata. The software runs on Windows, macOS, Linux, Android and iOS. In comparison, Signal is pretty much mobile only.

One downside, when I first looked at Session, was that there was no getting-started hand holding for newbies. Now there is a 5-page Lite paper Send Messages Not Metadata. But, it is useless for newbies. By nerds for nerds.

October 2024: On his Security Now podcast, Steve Gibson was impressed with Session when he first ran across it. On the October 29th edition of the show he said: "I wasn’t aware of the 'Session' messaging app, but it looks quite interesting ... It appears to be what you would get if you were to combine the ultra-robust and well proven Signal protocol - which Session forked - with the distributed IP-hiding Tor-style Onion routing which we briefly discussed again recently. And on top of all that, Session is 100% open source ... Session's messaging transport was deliberately designed like Tor's to hide each endpoint's IP address through a multi-hop globally distributed server network, and that the entire content of the messages used the impenetrable Single protocol used by Signal and WhatsApp to exchange authenticated messages between the parties ... From here it appears to be a total win. Establishing an anonymous identity with a public/private key pair is exactly the right way to go and that's exactly what they do plus much more and all with their source code being openly managed on Github."

October 22, 2024: Encrypted Chat App 'Session' Leaves Australia After Visit From Police by Joseph Cox for 404 Media. This was the original story. You have to subscribe to their newsletter to read the entire article. Quoting: "Session, a small but increasingly popular encrypted messaging app, is moving its operations outside of Australia after the country’s federal law enforcement agency visited an employee’s residence and asked them questions about the app and a particular user. Now Session will be maintained by an entity in Switzerland."

November 4, 2024: Encrypted messaging app developer moves out of Australia after police visit employee's home by Josh Taylor for The Guardian. Quoting: "Developed in Australia in 2018, Session is an encrypted messaging app that is open source and decentralised. The app runs on the tagline: 'Send messages, not metadata.' It allows users to send messages with anonymity, by opting for 66-character account IDs rather than verifying a user via emails or phone numbers. Messages are sent over a decentralised onion routing network similar to Tor (a popular encrypted browsing app) and no single server knows the message origins or destination."

I first heard of the end-to-end encrypted messenger Olvid in December 2023 when the French government mandated its use. See French government recommends against using foreign chat apps by Bill Toulas of Bleeping Computer (Decr 1, 2023). The Prime Minister of France requested that all government employees uninstall foreign communication apps such as Signal, WhatsApp, and Telegram in favor of the French messaging app Olvid.

About Olvid:

1. The software is open source and has been audited by techies working for the French government
2. There is a free tier and a paid tier. Encrypted texts are free. Receiving encrypted voice calls is free. Initiating encrypted voice calls is not free. Using Olvid on multiple devices is not free.
3. No personal information is needed to use Olvid. No phone number, no email, no name, no address, no date of birth. Nothing.
4. Olvid runs on iOS and Android, as does everything else listed on this page. But . . . they also provide installable software for macOS and Windows.
5. There is no central directory that connects users. Good for security not great for usability.
6. Unlike competing software it does not nag for access to your contracts/address book
7. It does not rely on any trusted third party
8. They guarantee your privacy even if their servers get hacked.
9. No SIM card required, just Internet access.

In December 2023, Steve Gibson, on his Security Now podcast said, "... it looks pretty good ... Olvid is not some random homegrown messaging app designed by the Prime Minister’s nephew ... I really like its integration with the desktop. That's something I've been missing as a crossplatform iOS and Windows user. And Signal is annoying with its required tie to a phone number."

Assorted: See their FAQ. Secure audio calls are not yet supported on Windows and macOS. They make no mention of ChromeOS support. A feature called Olvid Web lets you use Olvid in a web browser on Windows, macOS and Linux. But, you need an Android compatible device to serve as a gateway.

Under the right conditions, messages sent with the Google Messaging app on Android to another user with the Google Messaging app, are fully end-to-end encrypted.
The conditions:

• You must be using the Messages by Google app, not a messaging app from the hardware vendor or from your cell service provider.
• All participants must have the RCS option enabled.
  Open the Messages app -> in to right corner click on your picture or letter -> Messages settings -> RCS chats -> on
  Note that there is also an option to "Automatically re-send as text". If you always want secure messages, turn this OFF
• RCS encrypted messages require that data is enabled, be it Wi-Fi or 4G or 5G or LTE. Plain text messages do not require data.

Note: when messages are encrypted, a very small padlock icon will appear inside the send button and timestamps. In addition, it will say "RCS chat with xxxx"

See also:

1. RCS chats by Google FAQ from Google
2. messages.google.com
3. Turn on RCS chats in Google Messages from Google
4. Use end-to-end encryption in Google Messages from Google.
5. Learn about Rich Communication Services (RCS) messaging from Google.

Trusting Facebook (aka Meta Platforms) is a mistake.

As of November 2023: Facebook Messenger is not end-to-end encrypted by default, but it can be enabled. It might be called Vanish Mode or a "Secret Conversation". Encrypted conversations are not available on the Facebook website.

Starting December 2023: Perverts rejoice. Facebook has started to enable end-to-end encryption in Messages by default. The full roll-out will take time. They said: "It will take a number of months to complete the global roll-out. When your chats are upgraded, you will be prompted to set up a recovery method, such as a PIN, so you can restore your messages if you lose, change or add a device." Where this new PIN fits in is not clear to me. This does not apply to group messaging, that, is still being tested and is planned for the future. It does apply to calls and to the Facebook platform itself. When E2EE works correctly, Facebook has no access to the messages. But, one person can still report a bad message to Facebook which does give them access. I have not seen a discussion of backups. If the backups are not encrypted, then this is a sham. More: Meta rolls out default end-to-end encryption on Messenger, Facebook by Bill Toulas of Bleeping Computer.

June 27, 2023: Meta is rolling out new parental control tools for Instagram and Messenger by Ivan Mehta for Techcrunch. The new system pre-emptively blocks unwanted DMs on Messenger and Instagram, and nudges teens to take a periodic break. See it at the Meta Family Center.

January 2023: Facebook/Meta is planning to add more users to the end-to-end (read, fully) encrypted version of Facebook Messenger over the next few months. Users will be chosen at random and notified by Facebook. The fully encrypted version of Messenger now supports link previews, chat themes, user active status, and Android floating bubble mode. More.

In August 2022, Facebook turned over their badly encrypted chat logs to the police who arrested a teenager for getting an abortion. See This Is the Data Facebook Gave Police to Prosecute a Teenager for Abortion by Jason Koebler and Anna Merlan of Motherboard. Just after this s--- hit the proverbial fan, Facebook started testing end-to-end encryption for certain Messenger chats. I don't know how they define "certain" Here is their press release about this. Do not trust Facebook.

iMessages are end to end encrypted between Apple users. Blue messages are encrypted, green are not.

iMessage can fall back to un-encrypted text messaging, if need be. To prevent this fallback:
Settings -> Apps -> Messages -> disable the "Send as Text Message" option. Last verified on iOS 18.2.

FaceTime phone calls are also end-to-end encrypted.

iMessage supports group chats. iOS version 18 was released September 16, 2024. From what I have read, once an Android device joints a group chat, there is no encryption at all, not even amongst the Apple devices in the chat.

Encrypted chats can be backed up to iCloud, where all bets are off. Apple gives your iCloud data to assorted government agencies as the law requires. Consider disabling iCloud backups and checking that it remains disabled as iOS is upgraded to new versions. At the least, turn off iCloud backups of your chats.

Apple says they can not read encrypted iMessages and we are supposed to assume that this means no one can. That is not necessarily true. Apple can add a government agency to an existing chat. In this case, Apple can not read anything, but the government agency can.

Configure system settings so that messages are only saved for a set amount of time.

Focusing on encryption is relatively easily, verifying the identity of the person you are communicating with is a whole other thing, complicated by the fact that one person can use multiple iOS devices. iOS 17.2 is scheduled to have a new optional feature, called Contact Key Verification, that improves this identity verification. Bad news: How it works is complicated both at the technical level and at the user interface level. After reading about it, I was lost. Good news: This is not intended for everyone to use. It solves a problem that only people with significant reason to believe that spies or governments want to compromise their communications.

From this article: Upcoming Contact Key Verification Feature Promises Secure Identity Verification for iMessage by Glenn Fleishman for Tidbits (Nov. 8, 2023). "Apple relies on increasingly outdated notions of end-to-end security for your messages with other people. While the company has regularly applied fixes to iMessage and its Messages apps to improve security and privacy, it hasn’t kept up with industry lessons and innovations."

One part of this system that I did understand is that the identity verification has to occur outside of Apple's world, which is good. Quoting the above article: "... you want a separate out-of-band pathway that can’t be subverted. Security experts typically recommend you do this in person or by secure end-to-end video where you can see each other (FaceTime, or Zoom with its end-to-end option enabled). You should also be able to rely on a non-secured voice call, but you may want to have established some answers or code words to eliminate the possibility of an attacker using an AI voicebot to fool you - with a sufficient sample of the target’s speech, they're pretty good."

One problem with any app on a mobile operating system is the operating system itself. Cellphones are spying machines. I think the best security has to reside on a different OS. One aspect of this is that the end user can not see the encryption. With a web browser, there is a lock icon that insures data is encrypted in transit. There is nothing like this with mobile apps. Another aspect is Location tracking. Mobile Operating Systems really want to track their location. Some people know how to deal with this, but many do not.

Another problem with the above Secure messaging apps is that they require software to be installed and learned. For many non techies, this can be too much to deal with.

My suggestion for secure communication is to use plain old simple boring webmail. Anyone can use webmail, even non techies. But not all webmail, of course, just webmail between two users of the same secure email provider. Two good choices would be ProtonMail and Tutanota, there are probably others.

I am out of step here with every techie in the world.

Neither ProtonMail nor Tutanota can read messages sent between their customers. Both offer free and anonymous accounts. Using webmail means that the browser can prove that encryption is being used. Webmail can also be used on a Chromebook running in Guest mode. Guest mode offers a virgin OS, with no information about you at all, and it is guaranteed to leave no trace of your actions. Guest mode insures the only running software is the Chrome browser. It can not be infected with malware.

With ProtonMail, the world can see the FROM and TO address of emails between two ProtonMail users. Since these can be anonymous, no big deal. The world can also see the subject line and the name of any attached file. Forewarned is forearmed. The world can not see the body of emails or the contents of attached files. Not just the world, the Proton company itself has no access.

FYI: ProtonMail includes protection from Homograph attacks and Enhanced tracking protection.

When it comes to erasing messages after you send them, a Chromebook in Guest Mode is your best bet. Guest Mode erases everything when you log out. Everything. At the operating system level. There is no need to worry about how and where sent/received messages are saved. If a Chromebook is seized by law enforcement, there is nothing on the computer to indicate that webmail was used.

The secure Email company knows the pubic IP address that you connect to their service from. If they were compelled, they might have to provide this information to law enforcement. There are three defenses: use a VPN, use Tor or never connect from a place associated with you (home and office, obviously). This needs to be done when creating an account too. If you pay for a VPN, then the VPN provider knows who you are. To combat this, use a free limited account from ProtonVPN or Windscribe or Tunnelbear or another company. Or, pay for the VPN in cash or with a gift card. Or, have someone else pay for the VPN service.

PROTON MAIL APPS

If you use the ProtonMail app on either iOS or Android, be aware that it can be protected by an app run password. This is a short number (they call it a PIN code) that must be entered before the app can run. This is a great feature as it provides protection against someone who has your unlocked mobile device. It also lets you protect the account with a very long password, while providing a shorter one for everyday use.

- - - - - - - - - -

On Android, I tested this on Android 14 using app version 4.0.11 in May 2024. To enable the app run password: Settings -> Auto Lock -> ON. This prompts for a numeric PIN code. The minimum length is 4 digits. The maximum is not obvious. Another aspect to this is when the app lock kicks in, which is controlled by the "Auto Lock Timer" setting. This defaulted to the most secure value: "immediate". Other timing options ranged from 5 minutes to a full day.

While configuring the Android app, maybe turn off these options: Anonymous Telemetry and Anonymous crash reports.

From Proton: How to use the auto-lock feature on Android. This is sad. The article has no dates, so it might have been written in the 1970s. It is also wrong about the length of the PIN (it says the only length is 4 digits). And, there is no provision for feedback about the article. Disgracefully amateurish. I did contact Proton and they said (May 2024) that the PIN can be up to 8 digits.

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On iOS, I tested this on iOS 17.4 with app version 4.14.0 in May 2024. You set the app run password at: Settings -> App PIN. To control when the PIN code is requested, set the Timing option, which ranges from 1 to 60 minutes. It is annoying that the same features have different names on iOS vs. Android. Again, amateurish.

From Proton: How to set up Face ID, Touch ID, and PIN code lock on the Proton Mail iOS app. This article too has no dates and no provision for feedback. But, it does say that the PIN code length is from 4 to 21 characters. This is, technically, wrong. The PIN code is numeric. Saying "characters" implies that it accepts letters. It does not. Interesting that on Android, the maximum PIN length is 8 digits. The article also covers turning on AppKey protection. It does not, however, explain what this is.

From Proton: Security recommendation: enable Face ID or PIN protection on the Proton Mail iOS app Last updated June 12, 2023.