The Secria glossary
Encryption comes with a lot of jargon. Here’s what the words mean, in plain language, with links to the standards and sources behind them.
Quantum and post-quantum
The terms behind the move to encryption that quantum computers can’t break.
Q-Day
The day a quantum computer can break the encryption most of the internet relies on.
Read the definitionHarvest now, decrypt later
Recording encrypted data today to unlock it once quantum computers can.
Read the definitionShor’s algorithm
The quantum algorithm that could break RSA and elliptic-curve encryption.
Read the definitionML-KEM
The NIST standard for agreeing on a secret key in a way quantum computers can’t break.
Read the definitionLattice-based cryptography
Encryption built on hard problems about grids of points, and the math behind ML-KEM.
Read the definitionHybrid encryption
Combining two kinds of cryptography so each one covers the other’s weakness.
Read the definition
Encryption basics
How your data stays yours, in plain words.
End-to-end encryption
Only the sender and recipient can read a message, not the service carrying it.
Read the definitionZero-access encryption
Your data is stored with keys the provider doesn’t have, so it can’t read it.
Read the definitionEncryption at rest vs in transit
Protecting data while it moves versus while it’s stored, and why you need both.
Read the definitionTLS
The protocol that encrypts data moving between two computers, on the web and in email.
Read the definitionForward secrecy
Fresh keys for every session, so a stolen key can’t unlock the past.
Read the definitionX25519
The fast elliptic-curve key exchange behind most secure connections today.
Read the definitionEmail alias
An extra address that delivers to your inbox, so your real one stays private.
Read the definition
Email security and privacy
How email shows who sent it, stays protected on the way, and what it gives away.
SPF
The DNS record that lists which servers may send email for a domain.
Read the definitionDKIM
A digital signature on every email that shows which domain sent it.
Read the definitionDMARC
The policy that tells receivers what to do with email that fails SPF and DKIM.
Read the definitionMTA-STS
A policy that makes other mail servers deliver to a domain only over secure TLS.
Read the definitionSTARTTLS
The command that upgrades a plain mail connection to an encrypted one.
Read the definitionPGP
A long-standing way to encrypt and sign email with a public and private key pair.
Read the definitionS/MIME
Email encryption and signing built on certificates from a certificate authority.
Read the definitionEmail header
The technical lines on top of every email that record its sender, route and checks.
Read the definitionTracking pixel
The invisible image that tells a sender when, where and how often you opened an email.
Read the definitionMetadata
The data about your data: who, when and where, and what it reveals on its own.
Read the definition
VPN
What a VPN actually does under the hood.
WireGuard
The fast, modern VPN protocol with a small codebase and fixed, modern cryptography.
Read the definitionVPN kill switch
Blocks your internet the moment the VPN drops, so nothing leaks outside the tunnel.
Read the definitionDNS leak
When website lookups slip outside your VPN and show which sites you visit.
Read the definitionMulti-hop VPN
Routing your traffic through several VPN servers so no single one sees the whole path.
Read the definitionRAM-only server
A server that runs entirely in memory, so nothing survives a reboot.
Read the definitionSplit tunneling
Choosing which apps use the VPN tunnel and which use your normal connection.
Read the definition
Explained on the blog
Longer explainers for terms we’ve already covered in depth.
Email that’s ready for what comes next.
Post-quantum encryption on every plan, free included.