Introduction: Is Your "Privacy" Just an Illusion?

It's September 2025. We are living in times that researchers increasingly refer to as "surveillance capitalism." Sounds like the title of a cheap sci-fi movie, right? Unfortunately, this is our reality. Every day, we trade our privacy for convenience. We pay with our data for free apps, colorful stickers, and the ability to send a cat GIF in 0.3 seconds. However, this convenience has a dark side, as proven by a recent investigation in which journalists identified an anonymous person based on publicly available data.

But have you ever wondered what actually happens to your messages after you hit "Send"?

In today's comprehensive guide, we will dismantle the most popular messengers: WhatsApp, Signal, and Telegram. We’ll bust a few myths (especially those about Telegram), and for dessert, I’ll serve you a main course for true digital gourmets: a PGP user guide.

Why now? Because we are standing on the threshold of the post-quantum era. The intelligence strategy known as "Harvest Now, Decrypt Later" is not a conspiracy theory, but a real threat. What you encrypt today with a weak key could be bedtime reading for AI algorithms in 10 years.

Brew some coffee. This is going to be a long, but damn important read.

Part I: Foundations, or What's the Deal with the Envelope?

Before we dive into the apps, we need to understand two concepts without which any discussion about privacy is like talking about quantum physics over a beer—theoretically possible, but usually leads to wrong conclusions.

1. End-to-End Encryption (E2EE) – Your Gold Standard

Imagine you have a magical, armored box. You put a letter inside, lock it with a padlock, and the key is held only by your recipient. You give the box to a courier. The courier (the service provider) can shake the box, X-ray it, or even try to open it with a crowbar in the back room (e.g., upon a court order). They can't do it. This is End-to-End Encryption.

In this model, the intermediary server is a "blind courier." It doesn't know what it's carrying. This is the absolute baseline in 2025. If a messenger doesn't have this (looking at you, default Telegram), you are essentially sending postcards that anyone at the post office can read.

2. Content vs. Metadata – The Devil is in the Details

This is where most users fall into a trap. "But my messages are encrypted, so I'm safe!" Wrong. Encryption protects the CONTENT (what you wrote). But it does not protect the METADATA (the context).

Metadata is the writing on the envelope:

Who is writing?
To whom?
At what time?
From which location (IP address)?
How often do you talk?

Intelligence agencies and advertising corporations love metadata. It is often more valuable than the content itself. If an algorithm knows that you called a suicide hotline at 2:00 AM, and then a divorce lawyer, it really doesn't need to know the content of the conversation to know what's happening in your life. Remember: E2EE protects the content; system architecture protects (or sells) the metadata.

Part II: Battlefield Overview – What to Choose?

Let's X-ray the Big Three messengers using the latest technical knowledge.

1. WhatsApp – The Convenient Spy in Your Pocket

Over 2 billion users. The standard. If you don't have WhatsApp, for many people, you don't exist.

Content Security: Very good. WhatsApp implements the Signal Protocol (the same as the Signal app). Your messages are mathematically secure. Meta (Facebook) cannot read them.
Metadata Privacy: Catastrophic. WhatsApp is a "metadata mine" for Mark Zuckerberg. The app knows who you talk to, for how long, where you are, and what phone model you have. This data builds your "social graph," which is monetized.
The Backup Trap: This is a "game changer" for many. By default, WhatsApp backs up chats to Google Drive (Android) or iCloud (iOS). These backups are NOT encrypted with the user's key. If the police knock on Google's door with a warrant, they get your chat history on a silver platter, bypassing WhatsApp's encryption.
- The Solution: You must manually enable "End-to-end encrypted backups" in the settings. Hardly anyone knows about this.

Verdict: Good for talking about the weather with grandma. Unsuitable for confidential matters.

2. Telegram – Marketing Genius, Cryptographic Hollow Shell

Telegram has a reputation as "that secure messenger for rebels." Unfortunately, this reputation is mostly due to great PR.

Default Lack of E2EE: This is the most important thing you need to remember. Regular chats ("Cloud Chats") and GROUPS in Telegram are not End-to-End encrypted. They are only encrypted in transit (between you and the server). This means Telegram admins have the keys and technical access to your content. In the event of a data leak or court order—your conversations are visible in plain sight.
"Secret Chats": Yes, Telegram has E2EE encryption, but only in "Secret Chat" mode. You have to enable it manually for each person. It doesn't work in groups. It doesn't sync between phone and computer. Inconvenient and rarely used.
Proprietary Cryptography: Instead of proven standards, Telegram uses its own MTProto protocol. In the world of cryptography, the rule is: "don't roll your own crypto." Experts have repeatedly pointed out vulnerabilities in it.

Verdict: Great as an information channel (news). Risky as a private messenger. Treat it like a public network.

3. Signal – A Fortress for Everyone

Signal is the gold standard. Created by a non-profit foundation, it doesn't sell data, and it survives on donations.

Zero Knowledge Architecture: Signal knows only two things about you: when you created your account and when you last connected to the server. It doesn't know who you write to, it doesn't have your contact list, it doesn't see your groups.
Sealed Sender: Unique technology. The sender sends a message to the server in such a way that the server knows where to deliver it, but cryptographically does not know who sent it. Brilliant in its simplicity.
Post-Quantum Readiness: In 2025, Signal implemented PQXDH and SPQR protocols. These are next-generation safeguards, resistant to quantum computers. They protect your conversations today from being decrypted in the future.
New Feature - Usernames: Finally! You no longer have to give your phone number to strangers. You can use a nickname.

Verdict: The only reasonable solution for people who value real privacy.

Part III: PGP/GPG – For Those Who Want Full Control

If Signal is a comfortable, armored Mercedes, then PGP (Pretty Good Privacy) is a tank you have to assemble yourself in the garage. It's older, harder to use, lacks emojis, but gives you something priceless: Digital Sovereignty.

In PGP, you don't rely on any central server (like in Signal or WhatsApp). You encrypt the message on your computer and send it as a string of characters. You can send it by email, print it out, or even dictate it over the phone.

How does it work? (Short Theory)

PGP is based on asymmetric cryptography. You have two keys:

Public Key (The Padlock): You give it to everyone. Put it on your website, email footer. Anyone can take your "padlock" and lock a message for you.
Private Key (The Key): ONLY you have it. Only your key opens what was locked with your public key.

Tutorial: How to Start with PGP in 2025?

Forget about black terminals and command lines (unless you want to). Today, PGP is "clickable." Here is a step-by-step guide for Windows (macOS users look for GPG Suite, and Linux users know what to do).

Step 1: The Armory (Installation)

Download the Gpg4win package. It includes the Kleopatra program—this will be our command center. It is free and open-source. For Thunderbird users: The latest versions have built-in OpenPGP support, which makes things much easier, but Kleopatra gives you more control over files.

Step 2: Forging the Sword (Key Generation)

Launch Kleopatra.
Click File -> New Key Pair....
Select Create a personal OpenPGP key pair.
Enter your Name (or pseudonym) and email address. This will be your identifier.
IMPORTANT: Click Advanced Settings and make sure the key is at least 3072 bits long (preferably 4096 bits RSA or Ed25519). In 2025, weaker keys are asking for trouble.
Check the option to protect with a passphrase.
Click Create.
The program will ask for a Passphrase. It can't be "Password123". It must be a sentence. E.g., "MyAuntMakesTheBestDumplingsInBerlin2025!". If you forget this password, your data is lost forever. There is no "Remind password" option.

Step 3: Insurance Policy (Revocation Certificate)

Immediately after creating the key, Kleopatra (or another program) will suggest creating a Revocation Certificate. Do it! Save this file on a USB drive and hide it deep in a drawer. Why? If someone steals your private key or you forget your password, this file allows you to announce to the world: "This key is burned, do not use it." Without this file, your old "zombie key" will circulate on the net forever.

Step 4: Exchanging Padlocks (How to start writing?)

To send a secret letter to Mark:

Mark must send you his Public Key (.asc or .gpg file).
In Kleopatra, click Import and select Mark's file.
Verification (Fingerprint): This is the moment you feel like a spy. After import, you will see a string of characters (Fingerprint), e.g., A1B2 C3D4 E5F6....
Call Mark (preferably on Signal) and ask: "Mate, give me the first and last 4 characters of your Fingerprint."
If they match—right-click on Mark's key in the program and select Certify. This means: "I checked, it's definitely Mark, not an agent impersonating him."

Step 5: Encryption

You have a file secret_plans.docx.

In Kleopatra, click Sign/Encrypt.
Select the file.
Select Encrypt for others and select Mark's key.
The program will spit out a file secret_plans.docx.gpg.
Send this file by email. Only Mark can open it using his password.

Limitations of PGP (Because nothing is perfect)

Before you feel like a cybersecurity god, remember the flaws of PGP:

No Perfect Forward Secrecy (PFS): This is the biggest pain point. If someone obtains your private key in 5 years, they will decrypt EVERY message you ever received in the past. Signal (thanks to the "Double Ratchet" mechanism) changes keys with every message, so this problem does not exist there.
Metadata Leak: PGP encrypts the email body and attachments. But it DOES NOT ENCRYPT the Subject line or headers (From, To). If you title an email "Bank Robbery Plan" and send it via PGP, well... congratulations.

Summary: Your Strategy for 2025

You don't need to be Edward Snowden to care about privacy. Simple habit changes are enough.

For daily conversations: Switch to Signal. Enable disappearing messages. Set a PIN and registration lock. It's the best balance between convenience and security.
For family/work (if you must): Use WhatsApp, but immediately enable Encrypted Backups. Be aware that Meta knows who you are texting.
For matters of highest importance / file transfer: Learn PGP. Use it to encrypt sensitive documents before sending them to the cloud or via email.
Telegram: Leave it for reading memes and news from the front.

Remember, in cybersecurity, the only constant is change. Stay vigilant, update your soft, and don't be fooled by marketing slogans about "privacy" backed by a major corporation.

Safe surfing!

Alexander Cybersecurity Section Editor