Sphinx Packet Routing

Interactively peel each onion layer to see the cryptographic operations at every hop — from guard to exit.

Sphinx V1 · Onion Layer

Layer Inspector

Layers peeled0 / 5

Header Encryption

Outermost layer — AES-256-GCM encrypted routing header.

Ephemeral Key

0x3f9a2b1c…e84d7f62

Derived via HKDF-SHA256 from ECDH shared secret. Destroyed after use.

Cryptographic Operations

Sphinx V1 Parameters

Key Exchange

1
ECDH — Curve25519
Ephemeral key α multiplied by each node's long-term public key. Shared secret never transmitted.
2
KDF — HKDF-SHA256
Derives Kenc and Kmac from the ECDH shared secret. Unique keys per hop, zero reuse.
3
MAC — BLAKE2b-256 / Poly1305
γ tag verified before any decryption. Failed MAC → silent drop, no error signalling.
4
Stream — ChaCha20
β routing bytes XORed with keystream. Routing info only readable at the intended hop.
5
SURB — Single-Use Reply Block
Pre-built reply path embedded in the packet. Service can reply without learning the client's address.

Sphinx V2 · Post-Quantum

NIST PQC Level 3Hybrid ECDH + KEM

Guard

Derives Kenc₀, Kmac₀

α destroyed

Mix 1

Derives Kenc₁, Kmac₁

β destroyed

Mix 2

Derives Kenc₂, Kmac₂

γ destroyed

Exit

Derives Kenc₃, Kmac₃

δ destroyed

Dest

Payload delivered

θ destroyed