Original Title: "What are the privacy communication applications Session and SimpleX donated by Vitalik?"
Original Author: ChandlerZ, Foresight News
Ethereum co-founder Vitalik Buterin has recently turned his attention to a relatively niche field: privacy instant messaging. He posted on X, stating that end-to-end encrypted communication is crucial for privacy protection, and the next key steps involve "permissionless account creation" and "stronger metadata privacy protection." He specifically named two applications that are moving in this direction—Session and SimpleX—and donated 128 ETH to each.
This raises a specific question: in a landscape dominated by WeChat, Telegram, and WhatsApp, what differentiates these privacy-focused chat tools? What technological path is Vitalik betting on?
Why Vitalik Took Action: From Content Encryption to Metadata Privacy
Rather than focusing on "how much was donated," the issue Vitalik emphasized is more worthy of attention.
In his statement, existing end-to-end encryption only addresses the confidentiality of "message content," but there are two obvious shortcomings:
Account creation relies on phone numbers/email, making true "permissionless" impossible
· Mainstream IM (including many encrypted chat tools) requires registration with a phone number.
· This means that telecom operators, email service providers, and even regulatory agencies in various countries could become a "single point of dependency" for your digital identity.
Metadata remains highly exposed
· Who is chatting with whom, when, for how long, using which device, and which network—all of these are considered metadata.
· Even if the message content is encrypted, a sufficiently detailed social relationship map can still outline a person's life trajectory and relationship network.
Vitalik clearly pointed out in his tweet that breakthroughs in these two areas almost certainly mean moving towards a higher degree of decentralization. "Metadata privacy protection requires decentralization, which is inherently difficult to achieve; user expectations for multi-device support only complicate matters. Additionally, resisting witch attacks/refusal of service attacks in the message routing network and on the user end (without mandatory reliance on phone numbers) adds to the difficulty. These issues need more attention."
Session and SimpleX became the two projects he named and donated to. However, he also noted that neither of these applications is perfect, and there is still a long way to go to truly achieve the best user experience and security.
What is Session?
In a nutshell, Session is more like an encrypted chat tool that attempts to push Signal a step further: while maintaining end-to-end encryption, it aims to minimize the presence of phone numbers, centralized servers, and observable metadata in the system. On the surface, the usage of Session is not much different from ordinary IM—install the app, generate an account, add contacts, create groups, send text and files; these paths are familiar. But at its core, it has made several key changes to "accounts" and "message networks."
First is the account system. Session does not require users to provide a phone number or email. Upon first entering the app, the system generates a random Session ID for you, which serves as your unique identifier. The platform neither holds your real contact information nor needs to rely on telecom operators or email service providers to vouch for you. This directly bypasses the real-name or semi-real-name registration systems that mainstream IMs commonly rely on, making account creation more closely aligned with what Vitalik described as permissionless.
Next is the message transmission path. Session does not send all data to a centralized backend for forwarding and storage; instead, it is built on the Oxen blockchain and its Service Node network.
Simply put, these Service Nodes participate in block validation and also serve as message relays and storage within the network, forming a decentralized communication network. When messages are transmitted between nodes, they go through an onion routing mechanism similar to Tor, where each hop node only knows the previous and next hops, making it difficult to map out a complete communication relationship.
Of course, this architecture also brings about practical trade-offs in experience. Onion routing and decentralized storage naturally result in delays and stability issues compared to a direct connection to a centralized server; in terms of multi-device usage and message synchronization, Session currently cannot provide the seamless experience of automatically pulling all history when logging into a new device like Telegram or WhatsApp.
In May of this year, Session announced the official launch of its native token SESH and migration to Arbitrum. This token will be used to incentivize a DePIN network composed of over 2,000 nodes. In terms of token economics, the maximum supply of SESH tokens is 240 million, with 80 million unlocked at the initial issuance. Node operators must stake 25,000 SESH tokens to participate in network maintenance.
What is SimpleX?
Compared to Session, SimpleX has a more aggressive goal: it does not enhance privacy within the existing instant messaging framework but rather redesigns a communication method at the protocol level that aims to generate minimal aggregatable metadata.
In SimpleX, the two parties in communication do not send messages to each other as two accounts but instead use a series of pre-established one-way message queues to send and receive messages. You can think of it as: each relationship corresponds to a set of pipes that serve only that relationship, with messages relayed by intermediary servers. However, the servers only see data flowing from one queue to another, making it difficult to reconstruct a complete social relationship map from the protocol level.
Since there is no traditional global user ID in the system, external observers cannot analyze metadata on the server side to reconstruct who this person has been chatting with recently, how their connections are structured, or the community structure, as is possible with many centralized IMs.
This design has a significant impact on user experience. Compared to Session, SimpleX is less likely to give users the familiar feeling of being able to use it as an ordinary chat software right away. You cannot search for a username to add a friend like in Telegram; instead, you rely more on one-time invitation links, QR codes, or other out-of-band channels to establish connections. Multi-device usage, data backup, and migration no longer follow the paradigm of automatically syncing by entering a phone number or password, but require users to understand and cooperate with this privacy-driven workflow.
From the perspective of pursuing extreme privacy, these additional steps are necessary sacrifices; but from the perspective of the average user, they translate directly into a higher barrier to entry and mental burden.
For this reason, SimpleX is more like a niche tool aimed at users who are extremely concerned about metadata exposure and are willing to bear the cost of experience for it. It may struggle to gain a large mainstream user base in a short time, but it provides a very clear contrasting example in terms of technological path. If we truly prioritize reducing observable metadata over functionality, convenience, or user scale, what could instant messaging protocols be transformed into?
Vitalik's choice to donate funds to it largely supports this experiment of trying to erase user IDs and social graphs at the protocol level, allowing this relatively idealistic route more time for refinement and iteration.
Returning to the simple question, are these tools worth the attention of ordinary users?
When discussing Session and SimpleX, it is hard to avoid mentioning Signal, which has been the industry benchmark for "privacy chat" in recent years. Many encrypted communication protocols on the market today have adopted or drawn from the Signal Protocol to varying degrees. This protocol establishes a relatively mature engineering standard for end-to-end encryption using mechanisms like double Ratchet and forward secrecy.
For most users, as long as the chat partner is willing to switch platforms, Signal already provides a balanced choice in terms of security, usability, and cross-platform support. Its advantages—open-source implementation, end-to-end encryption of content, interface similar to mainstream IMs, and support for multi-platform use—make it one of the preferred tools for journalists, activists, developers, and privacy enthusiasts.
Vitalik Buterin stated at the 2025 Shanghai Blockchain International Week that with the development of ZK technology and cryptography, "Not your key, not your coin" will evolve into "Not your silicon, not your key," with hardware trust becoming a focus of development in cryptography and security. Currently, the marginal cost of the cryptographic technologies used by encrypted communication applications, including Signal, has become negligible, so users are unaware of it.
He believes that as encryption costs continue to decline, more applications will be able to utilize low-cost encryption technologies, shifting the question from "Why use ZK" to "Why not use ZK," and he looks forward to exploring new use cases with developers worldwide.
However, for industry practitioners and privacy-conscious users, the more realistic question may not be which tool will become the next WeChat, but rather two more specific choices.
Are you willing to pay a little more usability cost for privacy? Are you open to having one or two additional chat entry points reserved for specific relationships or scenarios outside the default world of WeChat/Telegram? In other words, we are not concerned about whether to replace the main IM entirely, but whether we can create an extra safe space for those truly sensitive conversations.
If your answer is yes, then these names may not need to wait until they gain mainstream attention to be worth considering. Even if they are unlikely to become the primary chat tools for ordinary users in the short term, Session and SimpleX, which Vitalik has named, at least provide two clear paths: one minimizes metadata and account dependencies within a familiar IM format; the other directly targets user IDs at the protocol level, aiming to prevent social graphs from being generated in the system.
In terms of whether they are worth the attention of ordinary people, they may not need to occupy the most prominent row on your phone, but they are certainly worth clearing a corner on your desktop for those conversations you do not wish to hand over to large platforms.
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