Struct SessionNullifier 

pub struct SessionNullifier { /* private fields */ }

A session nullifier for World ID Session proofs. It is analogous to a request nonce, it does NOT guarantee uniqueness of a World ID as a Nullifier does.

This type is intended to be opaque for RPs. For an RP context, they should only be concerned of this needing to be passthrough to the verifySession() contract function.

This type exists as an adaptation to be able to use the same ZK-circuit for both Uniqueness Proofs and Session Proofs, and it encompasses:

• the nullifier used as the proof output.
• a random action bound to the same proof.

The WorldIDVerifier.sol contract expects this as a uint256[2] array use as_ethereum_representation() for conversion.

Future

Note the session nullifier exists only to support the same ZK-circuit than for Uniqueness Proofs; as World ID evolves to a different proving system which won’t require circuit precompiles, a new circuit MUST be created which does not generate a nullifier at all, and the input randomized action will not be required either.

Implementations

impl SessionNullifier

pub const fn new(nullifier: FieldElement, action: FieldElement) -> Self

Creates a new session nullifier.

pub const fn nullifier(&self) -> FieldElement

Returns the nullifier value.

pub const fn action(&self) -> FieldElement

Returns the action value.

pub fn as_ethereum_representation(&self) -> [U256; 2]

Returns the session nullifier as an Ethereum-compatible array for verifySession().

Format: [nullifier, action] matching the contract’s uint256[2] sessionNullifier.

pub fn from_ethereum_representation(value: [U256; 2]) -> Result<Self, String>

Creates a session nullifier from an Ethereum representation.

Errors

Returns an error if the U256 values are not valid field elements.

pub fn to_compressed_bytes(&self) -> [u8; 64]

Returns the 64-byte big-endian representation (2 x 32-byte field elements).

pub fn from_compressed_bytes(bytes: &[u8]) -> Result<Self, String>

Constructs from compressed bytes (must be exactly 64 bytes).

Errors

Returns an error if the input is not exactly 64 bytes or if values are not valid field elements.

Trait Implementations

impl Clone for SessionNullifier

fn clone(&self) -> SessionNullifier

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SessionNullifier

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SessionNullifier

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for SessionNullifier

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<(FieldElement, FieldElement)> for SessionNullifier

fn from((nullifier, action): (FieldElement, FieldElement)) -> Self

Converts to this type from the input type.

impl From<SessionNullifier> for [U256; 2]

fn from(value: SessionNullifier) -> Self

Converts to this type from the input type.

impl Hash for SessionNullifier

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SessionNullifier

fn eq(&self, other: &SessionNullifier) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for SessionNullifier

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for SessionNullifier

impl Eq for SessionNullifier

impl StructuralPartialEq for SessionNullifier