1. SMS has no end-to-end encryption
When you send an SMS, your message is transmitted over the SS7 (Signaling System No. 7) network, the 1970s-vintage protocol that telecom operators use to route calls and texts between each other. SMS content is sent in plaintext. There is no end-to-end encryption, and there is no encryption between operators. Anyone with access to the SS7 backbone can read, copy, or modify the message in transit.
SS7 access is no longer limited to telecom carriers. It is commercially available. Researchers have demonstrated intercepting SMS from a laptop for a few dollars per subscriber. The protocol authenticates network nodes, not users, and it has no protection against a malicious or compromised operator.
2. Your telecom provider sees everything
Because SMS is plaintext inside the telecom network, your own operator can read every message you send. So can the recipient's operator, and so can every intermediary operator that handles the message on its way between them. Telecom providers also retain metadata (sender, recipient, timestamp, cell tower) and in many countries they are legally required to store this data for months or years.
This is the opposite of a zero-knowledge architecture. With SMS, multiple third parties see both content and metadata, on purpose.
3. Phone numbers are a weak identity anchor
SMS-based authentication ties your identity to a phone number, and a phone number ties to a SIM card, a telecom contract, and (in most countries) a government-issued ID. That chain is fragile in three ways:
- SIM swapping. An attacker social-engineers a telecom support agent into porting your number to a SIM they control. Once that succeeds, they receive every SMS you would have received, including one-time passwords for your bank, email, and social accounts. SIM swap attacks have been used to drain cryptocurrency wallets and hijack high-profile social media accounts.
- Number recycling. When a phone number is deactivated, telecom providers eventually reassign it to a new customer. Anyone who registers the new SIM can then receive SMS-based password resets for accounts you forgot to detach from that number.
- Telecom breach. Telecom databases are a high-value target. A breach exposes the mapping between phone numbers and the real identities behind them, permanently deanonymizing every account that relied on that number.
4. SMS has no forward secrecy
If an adversary records an SMS today and steals your SIM (or compromises a telecom log) tomorrow, they can read the message. SMS keys, where any exist, are held by the network, not by the endpoints. There is no per-message key, no ratchet, and no mechanism to make a recorded ciphertext useless once a key is compromised.
Modern end-to-end encrypted messengers use a Double Ratchet to derive a fresh key for every message, so a single compromised key does not expose past or future messages. SMS has none of this.
5. SMS metadata is inescapable
Even if the content of an SMS were encrypted, the telecom network would still log who messaged whom, when, and from which cell tower. This metadata is enough to map social graphs, identify journalists' sources, and target individuals for surveillance. SMS provides no way to hide it.
How beChat avoids these problems
beChat does not use SMS for transport, does not require a phone number, and does not collect the identifiers that make SMS-based systems fragile:
- PIN-based registration. Registration generates an 8-character PIN and a hardware-based device fingerprint on your device. The app never asks for a SIM card, telecom contract, or government ID.
- Encrypted data transport. Messages travel over an encrypted data connection using a Double Ratchet with post-quantum key exchange (ML-KEM-1024, ML-DSA-87). The SS7 network is never involved.
- Zero-knowledge server. The beChat server stores only encrypted blobs, your PIN, your device fingerprint, and your public keys. It cannot read message content.
- Forward secrecy. The Double Ratchet derives a fresh key per message. A compromised key does not expose past or future messages.
- SIM-swap immunity. Because accounts are not bound to phone numbers, a SIM swap cannot take over your beChat account.
Why SMS cannot be fixed
SMS was designed for a world where the telecom network was a trusted party and cryptography was expensive. Neither assumption holds today. SMS cannot be patched into being a secure messenger. Its problems are structural, not implementation bugs. The only fix is to stop using SMS for anything sensitive and to stop tying messaging accounts to phone numbers.
That is what beChat does. For the technical details of the cryptographic chain that replaces SMS, read how beChat works and the companion guide What is post-quantum encryption?
Frequently asked questions
Is SMS encrypted?
No. SMS is not end-to-end encrypted. The content of an SMS message is transmitted in plaintext over the SS7 (Signaling System No. 7) network that connects telecom operators. Anyone with access to the SS7 backbone, including third parties who purchase SS7 access, can intercept, read, and modify SMS messages in transit.
Can my telecom provider see my SMS messages?
Yes. Because SMS is not end-to-end encrypted, the telecom operators of both the sender and the receiver can see the content of every message. So can any intermediary operator that routes the message over SS7. Telecom providers also retain metadata such as the sender, recipient, and timestamp, and in many jurisdictions they are required to store this data for law enforcement.
What is a SIM swap attack?
A SIM swap (or SIM hijacking) attack is when an attacker convinces a telecom provider to port a victim's phone number to a new SIM card under the attacker's control. Once the port completes, the attacker receives all of the victim's calls and SMS messages, including SMS-based one-time passwords for banking, email, and social accounts. SIM swaps have been used in numerous high-profile cryptocurrency and social media takeovers.
Why is using a phone number for authentication a privacy problem?
A phone number is tied to a real-world identity through the telecom contract, billing data, and government ID submitted at activation. It is reused for account recovery across dozens of services, which makes it a single point of failure. It can be transferred to a new SIM by social engineering, and it can be recycled to a stranger after deactivation. When a messenger requires a phone number, your account is permanently bound to this fragile identifier.
Does beChat use SMS or phone numbers?
No. beChat does not use SMS for message transport and does not require a phone number to register. Accounts are created with an auto-generated 8-character PIN and a hardware-based device fingerprint. Messages are sent over an encrypted data connection using a Double Ratchet construction extended with post-quantum cryptography, not over SMS.
What is SS7 and why is it insecure?
SS7 (Signaling System No. 7) is the protocol telecom networks use to route calls and SMS messages between operators. It was designed in the 1970s on the assumption that only trusted telecom carriers would have access. Today SS7 access is bought and sold, and documented SS7 vulnerabilities allow attackers to intercept SMS, locate subscribers, and intercept calls. The protocol has no sender authentication and no encryption for message content.
Keep reading
Previous: What is post-quantum encryption?
Ready to try it? Join the open beta on Android.