Glossary · Argon2id
Argon2id
A memory-hard password-hashing function. Are We Friends? uses it to derive your master encryption key from your passphrase.
Argon2id is the recommended modern key-derivation function for turning a human-memorable passphrase into a cryptographically strong key. It won the 2015 Password Hashing Competition and is now the IETF-recommended choice for password hashing and key derivation.
The "id" variant is a hybrid of Argon2i and Argon2d that resists both side-channel attacks and time-memory tradeoff attacks. Its key property is being memory-hard: deriving a key requires substantial RAM (we configure it to use 64 MB), which makes brute-force attacks expensive even on specialized hardware (GPUs, ASICs).
Are We Friends? runs Argon2id in the user's browser at sign-in to derive a master key from their passphrase. That master key then unwraps the user's long-lived X25519 private key (which itself stays encrypted at rest in the user's browser storage). The passphrase itself never leaves the device. We never see it. We can't recover it. If you forget it, every DM thread you had is gone.
Related terms
End-to-end encryption (E2EE)
A messaging architecture where only the two parties can decrypt a message. The server never sees plaintext. Friends? DMs use this.
X25519
An elliptic-curve key agreement protocol. Are We Friends? uses it to wrap the per-thread DM keys.
XChaCha20-Poly1305
An authenticated symmetric encryption algorithm used to encrypt every Are We Friends? DM payload.
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