Glossary

29 terms

Argon2id

A memory-hard password-hashing function recommended by the Password Hashing Competition. DRIVUNO uses it to turn your password into a strong master key on your device.

Memory-hardness makes brute-force attacks on stolen wraps prohibitively expensive even with GPUs or ASICs.

Authenticated encryptionalso: AEAD

Encryption that simultaneously detects tampering. If a ciphertext is altered, decryption fails instead of returning corrupted data.

DRIVUNO uses XChaCha20-Poly1305 — an AEAD construction.

Blind index

A search-enabling technique using HMAC over plaintext values so the server can match exact terms (a file name, a mailbox subject) without ever seeing them in the clear.

DRIVUNO uses HMAC-SHA-256 blind indexes for file and mailbox subject search.

Ciphertext

The encrypted output. Bytes that mean nothing without the right key.

Client-side encryption

Encryption that happens on the user's device before data leaves the network boundary. The service provider only ever sees ciphertext.

Contrast with server-side encryption, where the provider holds the keys.

Cryptographic erasure

Deleting the key that protects data instead of (or in addition to) the ciphertext itself, rendering the data permanently unrecoverable.

DRIVUNO uses cryptographic erasure as part of the automatic purge that follows the 30-day account deletion grace period.

Ed25519

An elliptic-curve digital signature scheme. DRIVUNO uses it to sign share manifests so tampering is detected, not silently accepted.

End-to-end encryptionalso: E2EE

Encryption from sender to recipient with no readable intermediate. The transport, not the storage, is the focus.

A system can be E2EE without being zero-knowledge, and vice versa.

HKDF

HMAC-based Key Derivation Function. Used to derive purpose-specific subkeys from a single master secret.

HMAC

Hash-based Message Authentication Code. DRIVUNO uses HMAC-SHA-256 for blind-index search tags in the mailbox.

HMAC signature

A Hash-based Message Authentication Code used to prove a message came from the expected sender and was not altered in transit.

DRIVUNO signs outgoing webhooks with HMAC-SHA256 so subscribers can verify authenticity.

Key rotation

Replacing an encryption key with a new one on a schedule or in response to an event, without exposing the data it protects.

Team and folder keys rotate automatically whenever a member is removed.

Master key

The root key derived locally from your password via Argon2id. Used to unwrap per-file keys and to wrap recovery envelopes.

Metadata

Data about data: file sizes, timestamps, owner IDs. DRIVUNO encrypts what it can (file names, mailbox subjects) and minimizes the rest.

Nonce

A ‘number used once’ that ensures encryption with the same key produces different ciphertext each time. XChaCha20 uses 192-bit random nonces — safe for billions of operations.

Object lockalso: Immutable backup

A storage-layer setting that prevents a stored object from being modified or deleted until a fixed retention period elapses, even by an administrator.

DRIVUNO backups are held under a 30-day immutability lock before they can be overwritten.

Passkeyalso: WebAuthn

Hardware-backed credential standard from FIDO2. Replaces or augments passwords with public-key cryptography stored on a device or security key.

Recovery Key

A long, high-entropy string you write down at vault creation. Wraps your master key independently of your password. The only way to recover an account without a secondary channel.

REST-hookalso: Webhook

A webhook pattern where a client registers a callback URL via a normal REST call, letting automation tools like Zapier or Make subscribe to events without polling.

Row-Level Securityalso: RLS

A Postgres feature that enforces per-row access control inside the database itself. DRIVUNO uses RLS on every user-scoped table so a leaked query token cannot read another user's data.

Sealed box

An anonymous public-key encryption primitive from libsodium. Lets you encrypt a message to a recipient's public key without revealing your own identity. DRIVUNO uses it to seal file keys for shares.

Sealed envelope per member

A key-sharing pattern where a shared secret (e.g. a team folder key) is individually sealed with X25519 to each member's public key, so removing one member and rotating the key does not require re-encrypting the data itself.

Step-up authentication

Requiring an additional authentication factor at a sensitive moment — such as changing account recovery settings — even for an already-signed-in session.

Streaming AEAD

Authenticated encryption applied to a stream of chunks rather than a single buffer, so large files can be encrypted or decrypted progressively without ever holding the full plaintext in memory.

DRIVUNO uses a chunked secretstream construction built on XChaCha20-Poly1305 for large file transfers.

Trusted device

A device on which you have unlocked your vault and which holds keys derived locally. Trust is per-device — losing one does not expose your data on others.

WebAuthn

The browser API behind passkeys. Standardized authentication using public-key cryptography, often with a hardware authenticator.

X25519

An elliptic-curve key-agreement function. DRIVUNO uses it to seal file keys to recipients (account public keys, ephemeral share keys, team-member keys).

XChaCha20-Poly1305

An authenticated encryption scheme used to encrypt file content. The X variant uses a 192-bit nonce, large enough to use random nonces safely.

Zero-knowledge

A system property: the service provider has no technical ability to read user content. Keys never reach the server in usable form, only ciphertext does.