Kirill Abrams

Kirill Abrams's personal blog

Founder & CEO, UmbrellaX TOO

This is where I write about end-to-end encryption, post-quantum cryptography, jurisdictional risk, and the design decisions behind UmbrellaX. Personal opinions, not press releases.

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Blog

Essays, analysis and forecasts on private messaging, encryption, surveillance and the future of digital freedom, by Kirill Abrams.
Hands holding a phone with an RCS warning that resending as SMS removes end-to-end encryption.
Encryption

Is RCS encrypted? How to check your chat

RCS can be end-to-end encrypted, but support varies. Check the lock on iPhone and Android, understand missing encryption, and avoid an unsafe SMS fallback.

Oct 1 guide 10 min New
A person reviews a diagram separating Signal delivery queues from message history on personal devices.
Private messaging

Does Signal store messages? Server storage

Does Signal store messages? Learn what its servers queue, where message history remains, and how backups and legal requests change the privacy boundary.

Sep 17 guide 11 min New
A person enters a Signal registration-lock PIN while setting up a replacement phone.
Private messaging

Signal registration lock: what it protects and costs

Signal registration lock adds a PIN to re-registration. Learn what it protects, its seven-day recovery cost, and the account boundary it cannot remove.

Sep 12 guide 13 min New
Two people compare a Signal safety number on their phones in person.
Encryption

Signal safety number: how to verify it safely

Learn what a Signal safety number verifies, how to compare it safely, what a match cannot prove, and when automatic verification still needs a manual check.

Sep 8 guide 12 min New
A person checks a contact-joined notification on a phone during a commute.
Private messaging

Does Signal notify contacts when you join? The privacy answer

Does Signal tell your contacts you joined? Learn what their apps can see, how local contact-join alerts work, and what number-based identity still exposes.

Sep 3 guide 10 min New
A person starts a separate Telegram Secret Chat while sitting on an outdoor bench.
Private messaging

Telegram Secret Chat: what it protects and misses

Telegram Secret Chats add end-to-end encryption and self-destruct tools, but stay tied to two devices. A founder's guide to the real tradeoff.

Sep 1 guide 10 min New
A person adjusts WhatsApp privacy controls at home.
Private messaging

WhatsApp privacy settings: what to change first in 2026

A founder's practical WhatsApp privacy settings guide: what to switch on, what each control protects, and which risks settings cannot remove.

Aug 27 guide 12 min New
Two colleagues compare Signal and Telegram messaging defaults at a shared table.
Private messaging

Signal vs Telegram privacy: what actually changes

Signal vs Telegram privacy is not a feature checklist. Compare encryption defaults, cloud sync, phone numbers, contact discovery, and the tradeoffs that remain.

Aug 25 comparison 11 min New
A person reviews the difference between Signal registration and sharing a username.
Phone number

Can you use Signal without a phone number? (2026)

Can you use Signal without a phone number in 2026? The current answer, what usernames change, and the privacy boundary an account model still keeps.

Aug 20 guide 11 min New
A person examines four separate phone-number privacy boundaries on a tablet.
Phone number

Phone number privacy in messaging apps: the real test

Hiding a number is only the first privacy setting. A founder's guide to visibility, discovery, recovery, and choosing a stronger messenger.

Aug 13 guide 10 min New
A person reads an account warning after a mobile-number reassignment.
Private messaging

SIM swap attack and secure messaging accounts

A founder guide to SIM swap attacks, messaging-account takeover risk, prompt containment, and why UmbrellaX refuses a carrier-controlled account root.

Aug 11 guide 12 min New
A person makes a private voice call beside an illustration of its network route.
Encryption

Encrypted calling app: what I would trust

How I evaluate an encrypted calling app: media encryption, IP exposure, relay tradeoffs, verification, call logs, and UmbrellaX design choices.

Aug 6 guide 13 min New
Two people deliberately exchange messaging usernames at a first meeting.
Private messaging

Messaging app usernames: privacy test

A founder's guide to messaging app usernames, phone-number privacy, contact discovery, and why UmbrellaX treats usernames as identity UX.

Aug 4 guide 12 min New
A person pauses at a changed-encryption-key notification before sending a message.
Encryption

Key change notifications in encrypted messaging

A founder's guide to key change notifications, safety numbers, device trust, verification UX, and why UmbrellaX treats alerts as security.

Jul 30 guide 13 min New
A person chooses the scope and duration of location sharing on a phone.
Explainers

Location sharing privacy for messengers

A founder's guide to location sharing privacy in encrypted messengers: precise GPS, live sharing, consent, storage, and UmbrellaX defaults.

Jul 28 guide 10 min New
A person reviews a link-preview request before sharing a web address.
Explainers

Link preview privacy in encrypted messengers

A founder's guide to link preview privacy: URL fetches, IP leaks, operator knowledge, caching, and the UmbrellaX design test.

Jul 23 guide 10 min New
A person chooses selected photos instead of granting access to an entire photo library.
Explainers

Messaging app permissions: privacy test

A founder's guide to messaging app permissions, what to deny, and how UmbrellaX treats device access as a narrow privacy boundary.

Jul 21 guide 10 min New
A photographer checks location and other hidden photo details before sharing.
Metadata

Photo metadata privacy in encrypted messengers

A founder's guide to photo metadata privacy, EXIF location leaks, original-file tradeoffs, and UmbrellaX media stripping defaults before sensitive sharing.

Jul 16 guide 11 min New
A person adjusts read-receipt settings to control when a conversation reveals attention.
Explainers

Read receipts privacy in encrypted messengers

Read receipts can expose attention, timing, and device state. A founder's guide to safer receipt design in encrypted messengers like UmbrellaX.

Jul 14 guide 11 min New
A phone displays a limited lock-screen notification in a shared meeting space.
Explainers

Push notification privacy for encrypted messengers

A founder's guide to push notification privacy, what Apple or Google may see before a private chat opens, and why UmbrellaX keeps push quiet by design.

Jul 9 guide 9 min New
A person reviews a diagram of the different layers of messaging identity.
Private messaging

Anonymous messaging app: identity layers guide

A founder's guide to anonymous messaging apps: account identity, contact paths, network exposure, recovery, groups, and operator trust.

Jul 7 guide 12 min New
Two people consider a disappearing-message timer and the limits of deleting copies.
Private messaging

Disappearing messages privacy: what they miss

A founder's guide to disappearing messages privacy: screenshots, backups, metadata, groups, and why UmbrellaX treats deletion as a limit.

Jul 2 guide 10 min New
A person checks an alternative network route for a private chat.
Explainers

Censorship-resistant messaging: privacy test

A founder's guide to censorship-resistant messaging: shutdowns, blocking, transport fallback, phone-number risk, groups, and UmbrellaX design.

Jun 30 guide 13 min New
Two people compare identity, metadata, group and recovery criteria on a tablet.
Private messaging

Best encrypted messaging app: privacy test

A founder's 2026 guide to the best encrypted messaging app, with a privacy test for phone numbers, metadata, groups, jurisdiction, and UmbrellaX.

Jun 25 comparison 11 min New
Colleagues review membership and access to a private project room on a laptop.
Explainers

Secure messaging for business: governance guide

A founder's guide to secure messaging for business: off-channel risk, incident rooms, BYOD, retention boundaries, and privacy-first tools.

Jun 25 guide 12 min New
An older adult holds a recovery-key card beside a phone restoring an encrypted backup.
Backups

Encrypted chat backups: recovery privacy test

A founder's guide to encrypted chat backups, cloud restore, recovery keys, and why UmbrellaX separates account recovery from message history.

Jun 18 guide 11 min New
A person chooses an invitation link instead of syncing an entire address book.
Explainers

Contact discovery privacy in messengers

A founder's guide to contact discovery privacy: address-book upload, social graphs, blind matching, and why UmbrellaX keeps discovery optional.

Jun 16 guide 11 min New
A reader reviews Kazakhstan operator jurisdiction beside a diagram of content and retained records.
Explainers

Messenger jurisdiction: privacy risk guide

A founder's guide to messenger jurisdiction: Five Eyes pressure, CLOUD Act risk, metadata, legal requests, and why UmbrellaX minimizes operator data.

Jun 11 guide 12 min New
A lawyer and client review a confidential matter team on a tablet.
Explainers

Secure messaging for lawyers: client privacy

A founder's guide to secure messaging for lawyers: client confidentiality, metadata, phone numbers, matter teams, and UmbrellaX design.

Jun 11 guide 11 min New
Community volunteers prepare supplies and invite one person into an organising chat.
Explainers

Secure messaging for activists: field guide

A founder's guide to secure messaging for activists: protest group risk, metadata, phone numbers, device seizure, shutdowns, and UmbrellaX design.

Jun 4 guide 14 min New
A journalist checks a new contact invitation while waiting at a station.
Explainers

Secure messaging for journalists

A founder's guide to secure messaging for journalists: source contact, metadata, phone numbers, device risk, and how UmbrellaX thinks about it.

Jun 2 guide 13 min New
An engineer studies hybrid key exchange beside a timeline of long-lived private messages.
Explainers

Post quantum messaging: what actually matters

A founder's guide to post quantum messaging, harvest-now risk, ML-KEM, hybrid design, and why UmbrellaX hardens group chat early.

May 31 pillar 9 min New
Two people review a removed group member and a new group key on a tablet.
Encryption

Secure group messaging: what to check

A founder's practical test for secure group messaging: encryption defaults, group key changes, metadata, recovery, and why UmbrellaX uses MLS.

May 31 guide 9 min New
A researcher points to timing, connection and device metadata beside encrypted message content.
Metadata

Private messenger metadata: what E2EE hides

A founder's guide to private messenger metadata: what encryption does not hide, why logs matter, and how UmbrellaX reduces operator knowledge.

May 26 pillar 11 min New
A person on a sofa tries a labelled identity-design preview with a handle and no phone-number field.
Phone number

Messenger without phone number: privacy case

A founder's guide to phone numbers as identity, why they expose more than message content, and why UmbrellaX does not start from a telecom identifier.

May 21 guide 10 min New
Two people compare SimpleX pairwise connections with the planned UmbrellaX account model on printed cards.
Private messaging

UmbrellaX vs SimpleX: private messaging, no identifiers, and usable scale

SimpleX is radical about no identifiers. UmbrellaX is stronger as a default private messenger for groups, recovery, speed, jurisdiction, and normal use.

May 18 comparison 10 min New
A person compares WhatsApp phone-number registration with the pre-launch UmbrellaX identity design.
Private messaging

UmbrellaX vs WhatsApp: private messaging without Meta or phone number identity

UmbrellaX is stronger than WhatsApp for private messaging when Meta ownership, phone number identity, metadata, backups, and jurisdiction matter.

May 18 comparison 10 min New
Two engineers compare Signal sender keys with an MLS TreeKEM group diagram.
Encryption

Signal Protocol vs MLS: the bytes on the wire, the trade offs that matter

Signal Protocol and MLS (RFC 9420) both deliver end to end encryption. They diverge on groups, post quantum, and adoption surface. A builder's comparison from someone who picked MLS.

May 10 analysis 17 min New
A traveller compares Session onion routing with the planned UmbrellaX operator model on a tablet.
Private messaging

UmbrellaX vs Session: two answers to the no phone number question

UmbrellaX and Session both refuse phone number identity. Session went random Account IDs, onion routing, decentralised. UmbrellaX went MLS, post quantum, Kazakhstan. Five axes compared honestly.

May 10 comparison 17 min New
An analyst places a 2027 question-mark card on an uncertain Chat Control forecast timeline.
Regulation

Forecast: will EU Chat Control pass by end of 2027?

UmbrellaX forecast on CSAR. Current probability 30%. Rationale, factors that would move it up or down, resolution criteria, and revision schedule.

May 1 forecast 10 min New
A reader examines a Chat Control proposal diagram showing inspection before message encryption.
Regulation

EU Chat Control explained: the bill, the votes, and why E2EE cannot survive it

What the EU Chat Control regulation actually says, the voting timeline through April 2026, and why mandatory client side scanning is mathematically incompatible with end to end encryption.

Apr 30 analysis 11 min New
Two people message from separate homes, with a diagram showing that only endpoints read the content.
Encryption

End to end encryption explained: what it is, what it is not, and how UmbrellaX implements it

A byte level explainer of end to end encryption. What E2EE protects, what it does not, which protocols matter in 2026, and how UmbrellaX uses MLS plus post quantum hardening.

Apr 29 pillar 14 min New
Two people compare Signal and UmbrellaX operator jurisdictions on printed cards.
Private messaging

UmbrellaX vs Signal: honest comparison by the founder of UmbrellaX

UmbrellaX outperforms Signal on groups, jurisdiction, phone number independence, and scale. Signal has a longer legacy record, but UmbrellaX is stronger for my threat model.

Apr 28 comparison 14 min New
A person compares Telegram cloud and secret chats with the planned UmbrellaX encrypted-group defaults.
Private messaging

UmbrellaX vs Telegram: encryption by default, jurisdiction, and private messaging

UmbrellaX encrypts every chat end to end by default; Telegram does not. UmbrellaX runs from Kazakhstan, Telegram from the UAE after a French arrest. Concrete comparison by the founder of UmbrellaX.

Apr 28 comparison 12 min New