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Sign in with your invite and credentials. Your encryption key is derived from your password in this browser — it is never sent anywhere.
New here? excelsiorcomms.com is invite-only. Open the invite link you were sent to set up your account.
You've been invited to a private, encrypted workspace. Set your password to finish — your encryption key is derived from it in this browser and never sent anywhere.
ML-KEM-1024 (also called CRYSTALS-Kyber) is the key-encapsulation mechanism the U.S. National Institute of Standards and Technology selected as its post-quantum encryption standard in 2024 (FIPS 203).
Why it matters: today's encryption like RSA and elliptic-curve relies on math that a large enough quantum computer could break. An adversary can record your encrypted traffic now and decrypt it years later once such a computer exists — the "harvest now, decrypt later" threat. ML-KEM is built on lattice problems believed to be hard even for quantum computers, so it protects your messages against that future.
How it works here: when you send a message, your app uses the recipient's ML-KEM public key to encapsulate a fresh 32-byte secret. The 1,568-byte encapsulation ciphertext travels with the message; only the recipient's ML-KEM private key can recover that secret. The "1024" refers to the highest security parameter set — the strongest of the three ML-KEM variants.
X25519 is an elliptic-curve Diffie-Hellman key exchange over Curve25519, designed by cryptographer Daniel J. Bernstein. It's one of the most widely deployed and carefully studied key-exchange algorithms in the world.
Where you've used it: X25519 secures the majority of modern HTTPS connections (TLS 1.3), SSH, and the Signal messaging protocol. Its track record is exactly why we keep it in the mix rather than relying on post-quantum crypto alone.
How it works here: you and your recipient each hold an X25519 key pair. Combining your private key with their public key produces a shared secret that only the two of you can compute — without ever transmitting the secret itself. This is the "classical" half of the hybrid.
Rather than trust post-quantum cryptography alone (it's newer) or classical cryptography alone (vulnerable to future quantum computers), we combine both — the same "hybrid" approach adopted by Signal, Apple iMessage, and Google Chrome for their own post-quantum rollouts.
The guarantee: the two shared secrets — one from X25519, one from ML-KEM — are concatenated and run through SHA-256 to produce the final 32-byte message key. An attacker would have to break both algorithms to read your message. If a flaw is ever found in one, the other still protects you.
message_key = SHA-256( X25519_secret ‖ ML-KEM_secret )
XChaCha20-Poly1305 is the authenticated cipher that actually encrypts your message text using the hybrid key. ChaCha20 encrypts; Poly1305 adds an authentication tag.
Authenticated means tamper-proof: if even a single byte of an encrypted message is altered in transit, decryption fails outright rather than producing garbage. You can trust that a message you receive is exactly what was sent.
Why the "X": the extended-nonce variant uses a 192-bit random nonce, large enough that a fresh random value per message never collides — critical when every message uses its own key. It's the same cipher family used by WireGuard and modern TLS.
Devices signed in to your account. Removing a device immediately ends its access — it can't send or read messages until it signs in again.
ExcelComms is a private, end-to-end encrypted messenger. Everything you write is encrypted on your own device before it leaves it, and it can only be read by the people you send it to. The server that carries your messages stores them as ciphertext it has no ability to open — not for us, not for anyone who compromises the server, and not for anyone who compels us to hand data over.
It's built on modern, well-studied cryptography rather than anything homemade, and it's designed around a simple principle: the app should only claim protection it can actually deliver. The sections below say plainly what ExcelComms does — and, just as plainly, what it does not do.
Strong encryption protects the content of what you say. It does not make you invisible. ExcelComms does not hide metadata — the server can see which accounts are in a conversation and when messages are sent, even though it cannot read them. Voice calls are protected by DTLS-SRTP, which is not the post-quantum layer that protects messages. And while ExcelComms uses respected, standard cryptography, it has not undergone an independent third-party security audit. We'd rather tell you these boundaries than let a checkmark imply guarantees we can't back.
ExcelComms is operated by Most High Holdings LLC. Version 0.2.0 (Web). This is an early release under active development.
This Privacy Policy explains what information excelsiorcomms.com ("we", "us"), operated by Most High Holdings LLC, collects, why, and what we do and do not have access to. It applies to your use of the excelsiorcomms.com messenger and related services. Please read it alongside our Terms of Service.
excelsiorcomms.com is end-to-end encrypted. Your encryption keys are generated and held on your own device and are never transmitted to us. As a direct consequence, the contents of your messages and the audio of your calls are not available to us in any readable form. Most of this policy is therefore about the limited information we necessarily do handle to deliver those encrypted messages to the right place.
We want to be specific, because "encrypted" is often used loosely. We cannot read the text of your messages, the contents of files or images you send, or the audio of your voice calls. These are encrypted end-to-end and we do not hold the keys. No employee, administrator, or automated system on our side can decrypt them, and we cannot produce them in response to a request from anyone.
Encryption protects content, not the fact that communication is happening. Our server can see, and in the course of operating necessarily processes, information such as: which accounts exist, which accounts are members of a given conversation, and the timing and size of encrypted messages. In practice this means the service can infer who is communicating with whom, and when, even though it cannot infer what is being said. excelsiorcomms.com does not currently implement metadata-hiding features such as sealed sender. If concealing the existence or pattern of your communications is part of your threat model, you should account for this.
Voice calls connect directly between devices where possible, and the media is encrypted with DTLS-SRTP, so call audio does not pass through our servers in a readable form. To establish a call, participants exchange network address information, and our service uses connection-assistance ("STUN") servers for this step. This means the other participant's and the STUN provider's systems may observe IP address information during call setup. We are working to bring this connection-assistance in-house to reduce reliance on third parties; until then, a third-party STUN provider may be used.
We do not use your information for advertising, we do not sell or rent it, and we do not build advertising profiles from it.
We share information only in limited, necessary circumstances:
We keep information only as long as needed to provide the service. Encrypted messages are retained on the server until delivered and for two years thereafter, or until removed by a disappearing-message timer or by you. Account information is kept while your account is active. When you delete your account, we delete or de-identify associated information within two years, except where we must retain limited records to comply with law or protect the service.
To exercise any of these, contact Most High Holdings LLC, the operator of excelsiorcomms.com.
Note: a dedicated privacy contact email will be published here before general release.
excelsiorcomms.com is designed to protect your communications with end-to-end encryption, forward secrecy, and contact verification. No system is perfectly secure, and we do not claim excelsiorcomms.com is unbreakable or that it has been independently audited. In particular, because your keys are derived from your password and held only on your device, the security of your account depends on the strength and secrecy of your password, and lost passwords cannot be recovered.
excelsiorcomms.com is not directed to children under 18, and we do not knowingly collect information from them. If you believe a child has provided information to us, contact us and we will address it.
excelsiorcomms.com may be operated from, and information may be processed in, jurisdictions other than your own. By using the service you understand that information may be transferred and processed in those locations, with protections consistent with this policy.
We may update this policy as the service evolves. When we make material changes, we will update the effective date above and, where appropriate, notify you in the app.
Questions about privacy can be directed to Most High Holdings LLC, the operator of excelsiorcomms.com.
These Terms of Service ("Terms") govern your use of the excelsiorcomms.com messenger and related services provided by Most High Holdings LLC ("excelsiorcomms.com", "we", "us"). By creating an account or using the service, you agree to these Terms and to our Privacy Policy. If you do not agree, do not use the service.
You must be at least 18 years old, and legally able to enter into these Terms, to use excelsiorcomms.com. If you use the service on behalf of an organization, you represent that you are authorized to bind that organization to these Terms.
You are responsible for the activity on your account and for keeping your credentials confidential. excelsiorcomms.com is end-to-end encrypted and your encryption keys are derived from your password on your own device. This has an important consequence you must understand and accept:
You agree not to use excelsiorcomms.com to:
Because the service is end-to-end encrypted, we generally cannot see the content of communications and therefore cannot and do not monitor or moderate message content. Responsibility for what you send rests with you. We may act on abuse reports and on information available to us, including account and metadata signals, and we may suspend or terminate accounts that violate these Terms.
excelsiorcomms.com is an early-stage release (version 0.2.0) under active development and is provided on an "as is" and "as available" basis, without warranties of any kind, whether express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, and non-infringement. We do not warrant that the service will be uninterrupted, error-free, or perfectly secure. Strong encryption substantially protects your communications, but no security is absolute, and excelsiorcomms.com has not undergone an independent third-party security audit.
Features such as disappearing messages remove messages from view within the app on a timer. They cannot prevent a recipient from capturing, screenshotting, photographing, or otherwise preserving content before it disappears. You should treat anything you send as potentially retainable by the recipient.
The excelsiorcomms.com software, name, and branding are owned by Most High Holdings LLC and its licensors and are protected by applicable law. These Terms do not grant you rights to our trademarks or to use the software except as necessary to use the service as intended. You retain all rights to the content you create; you grant us only the limited, technical rights needed to transmit and store your (encrypted) content to provide the service.
You may stop using the service and delete your account at any time. We may suspend or terminate access if you violate these Terms, if required by law, or if necessary to protect the service or its users. Upon termination, your right to use the service ends; provisions that by their nature should survive (such as disclaimers, limitations of liability, and governing law) will survive.
To the maximum extent permitted by law, excelsiorcomms.com and Most High Holdings LLC will not be liable for any indirect, incidental, special, consequential, or punitive damages, or for any loss of data, communications, or profits, arising out of or relating to your use of (or inability to use) the service. To the maximum extent permitted by law, our total liability for any claim relating to the service will not exceed the greater of the amount you paid us for the service in the twelve months before the claim, or USD $100.
You agree to indemnify and hold harmless Most High Holdings LLC and its personnel from claims, damages, and expenses arising out of your misuse of the service or your violation of these Terms or of applicable law.
These Terms are governed by the laws of the State of Wyoming, United States, without regard to conflict-of-laws principles. Any dispute will be resolved in the courts or forum specified for the State of Wyoming, United States, unless applicable law requires otherwise.
We may update these Terms as the service evolves. When we make material changes, we will update the effective date above and, where appropriate, notify you in the app. Continued use after changes take effect constitutes acceptance.
Questions about these Terms can be directed to Most High Holdings LLC, the operator of excelsiorcomms.com.
Approve people your team invited, and remove anyone who should no longer have access. Admin invites let people in immediately; invites from non-admins land here for your approval.
Generate a private invite. You'll get a link and a verification code — send them to your contact through separate channels (e.g. link by email, code by text) so a leaked link alone can't be used.
Send these to your contact via two different channels. Both are needed to join. The invite expires in 48 hours.
This creates an encrypted backup of your keys, protected by a 24-word recovery phrase. It's the only thing that can restore your account — and your message history — if you ever forget your password. The phrase is generated on this device; the server only ever stores the encrypted backup.
Write these 24 words down in order and keep them safe. They will not be shown again.
Compare this number with your contact in person or over a call you trust. If they match, your conversation is secure and hasn't been intercepted.
New messages in this chat will disappear after the selected time.
This permanently destroys all encryption keys and message history on this device. It cannot be undone, and messages will become unreadable.