Nullifiers

• What is a nullifier?
• Refactor to describe generic nullifiers

The nullifier $\mathsf{nf}$ (an ${\mathbb{F}}_q$ element) is derived as the following output of a rate-3 Poseidon hash:

nf = hash_3(ds, (nk, cm, pos))

where the ds is a domain separator as described below, $nk$ is the nullifier-deriving key, cm is the state commitment, and pos is the position of the state commitment in the state commitment tree.

Define from_le_bytes(bytes) as the function that interprets its input bytes as an integer in little-endian order. The domain separator ds used for nullifier derivation is computed as:

ds = from_le_bytes(BLAKE2b-512(b"penumbra.nullifier")) mod q