Cryptographic Architecture
DropWire is designed with SPAKE2 password-authenticated key exchange, ChaCha20Poly1305 payload encryption, zero-knowledge relays, and BLAKE3 chunk verification.
SPAKE2 Key Exchange
Both sender and receiver securely agree on a shared encryption key using the generated room password. Unauthenticated or eavesdropping endpoints cannot decrypt or inject data frames into the streaming session.
Integrity Verification
Files and chunks are hashed using the ultra-fast BLAKE3 algorithm. Every chunk's hash is verified by the receiver prior to disk writing, preventing chunk tampering or corruption.
Explicit Threat Model & Limits
Relay Eavesdropping: Relay servers only forward SPAKE2 and ChaCha20 encrypted ciphertexts between room tokens (`happy-dog-42`). Relays cannot view filenames or plaintext byte content.
Room Code Safety: Room codes act as SPAKE2 passwords and single-use ephemeral session rendezvous points. Once a receiver completes transfer, the room code is invalidated automatically.