Signal vs Session: phone number or forward secrecy

Published 31 August 2026. Written by the Nyra team.

Signal keeps forward secrecy but requires a phone number. Session drops the phone number but also removed forward secrecy, which most cryptographers criticize. So the choice is a trade: identity protection versus long-term message protection. Nyra is being built to keep both, though it is still in development.

Signal and Session solve the same problem, private messaging, and make opposite compromises to get there. Signal keeps forward secrecy, the property most cryptographers treat as non-negotiable, but it requires a phone number. Session drops the phone number, which is exactly what some people need, but along the way it also dropped forward secrecy. That single trade is what this comparison is really about. Nyra, our own app, appears in a quiet third column below. It is in development, not launched, and not yet audited, so read those cells as a design goal, not a shipping fact. Signal and Session are both real software you can install today, and we wrote this to be fair to both.

The short version

Signal: forward secrecy, but a phone number

Signal is the best private messenger you can install today, and for most people it is the right choice. The Signal Protocol is the most scrutinized messaging cryptography in existence, formally analyzed and independently audited many times over. Clients and server are open source, group chats are end-to-end encrypted, and the whole thing is run by a nonprofit whose responses to subpoenas have shown it holds almost nothing about its users. Forward secrecy is built in through the Double Ratchet, so even if one of your keys leaks later, the messages you already sent stay unreadable.

The catch is a single field. Signal requires a phone number to register. Since 2024 a username can hide that number from the people you talk to, which genuinely helps, but the number still sits on your account, tied to your identity through your carrier. For a journalist's source, an activist under a hostile government, or anyone who simply does not want a real-world identity attached to their conversations, that field is the whole problem. It is a deliberate trade Signal made for spam resistance and easy contact discovery, and it serves an enormous number of people well. If that one requirement is what sends you looking elsewhere, that gap is why Nyra exists.

Session: no phone number, but no forward secrecy

Session deserves credit for proving that a messenger with no phone number can work at scale. Your identity is a random Session ID, registration asks for nothing personal, and messages route through a decentralized node network with onion routing that hides your IP address from the destination. The apps are open source and were independently audited in 2021. If avoiding a phone number is your only hard requirement, Session is the most established option that meets it.

The criticism is just as real. Session replaced the Signal Protocol with its own Session Protocol, and in doing so it removed forward secrecy. This is the most discussed weakness of Session messenger, and it is worth understanding rather than taking on faith. Forward secrecy means each message is protected by a key that is rotated and discarded, so compromising your device later does not unlock the conversations you already had. Without it, a single key that leaks in the future can retroactively decrypt past messages an attacker recorded and stored. Session argues the trade simplifies its decentralized design and enables features like multi-device sync without a central server. That argument has not convinced most cryptographers. One more thing worth knowing: small closed groups are end-to-end encrypted, but large public communities are not.

The trade, stated plainly

Line the two up and the decision is almost a single question. Signal gives you forward secrecy and the deepest audit history in the field, and asks for a phone number in return. Session gives you registration with no phone number, and asks you to give up forward secrecy in return. Neither one lets you keep both, and that is not an accident. Removing the phone number pushed Session toward a decentralized design, and that design is what its team used to justify dropping forward secrecy.

So the honest answer to "Signal vs Session" is a question back: can you attach a phone number to this account? If yes, Signal is the stronger pick, because forward secrecy and audit depth matter more than most people realize and the phone number costs you little. If no, Session is a reasonable choice, as long as you go in knowing that the messages you send today could be exposed if a key is compromised much later. If you want a fuller field of options that avoid a phone number, we keep an honest list of the best Session alternatives.

Where Nyra fits

Nyra is our attempt to refuse the trade instead of picking a side. Registration asks for nothing: your identity is a username plus keys derived from a recovery phrase, no phone number and no email, ever. And messages use X3DH with the Double Ratchet, the same construction Signal pioneered, built on independently audited cryptographic primitives, so forward secrecy stays intact. The goal is Signal-grade cryptography with Session-style registration. Our security page explains exactly how, and our full comparison of private messengers puts more apps side by side.

The caveats, stated as plainly as the rest: Nyra is in development, so you cannot install it today. The code is not yet public. The independent audit is planned before launch, meaning it has not happened yet, so nothing above is proven the way Signal's history is. And if you lose your recovery phrase, your account is gone forever, because there is no phone number or email to reset it with and nobody, including us, can restore it. Judge Nyra when it ships, not before.

Frequently asked questions