Struct FusedPowConfig 

pub struct FusedPowConfig { /* private fields */ }

A configuration for proof of work on the transcript sponge.

For bits > 0:

1. The prover sends the least passing nonce n < 2^(bits + 7) as canonical unsigned LEB128.
2. The verifier checks the nonce encoding and range. Both parties absorb the nonce and squeeze ceil(bits / 8) check bytes. The verifier rejects unless their low bits bits, read little-endian, are zero.
3. Both parties derive the verifier message from the following sponge output via Transcript::verifier_message.

At zero difficulty, both parties derive the verifier message directly.

Security

For fresh, independent uniform sponge output, the check passes with probability 2^-bits. The bytes after the check remain uniform. The soundness benefit depends on the protocol, sponge and challenge decoding. The difficulty, placement of this step and verifier-message type must be fixed by the protocol and bound in the session identifier.

Performance

The default helper searches sequentially on the calling thread. On a ProverState whose public sponge is Send, verifier_message_pow_parallel (feature parallel) searches on the Rayon pool and writes the same proof. With a permutation-backed sponge, when the nonce, the check bytes and the returned message fit in one rate block, a search trial costs about one permutation.

Errors

The prover returns VerificationError if:

• The search exhausts the nonce space.
• At positive difficulty, a custom transcript provides no Transcript::verifier_message_oracle.
• The live transcript rejects the nonce that passed the oracle check. The nonce has already been written, so discard the prover state.

The verifier returns an error if the nonce is truncated, noncanonical or out of range, if the check bits are nonzero, or if the transcript has already been rejected.

Panics

Panics if bits > 57: the u64 nonce space must hold 2^(bits+7) values.

Implementations

impl FusedPowConfig

pub const fn new(bits: u32) -> Self

Configure fused PoW at a protocol-fixed difficulty, from 0 through 57.

Panics

Panics if bits > 57.

Trait Implementations

impl Clone for FusedPowConfig

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for FusedPowConfig

impl Debug for FusedPowConfig

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

Formats the value using the given formatter.

impl Eq for FusedPowConfig

impl PartialEq for FusedPowConfig

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

Equality operator ==.

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

Inequality operator !=.

impl PowStrategy for FusedPowConfig

type Nonce = Leb128

The canonical, self-delimiting nonce codec. Integers use fixed-width encoding.

fn enabled(&self) -> bool

Whether to exchange a nonce and derive check bytes.

fn last_nonce(&self) -> u64

The inclusive nonce bound, starting at zero.

fn challenge_len(&self) -> usize

Number of verifier bytes derived after each candidate nonce.

fn accepts(&self, _nonce: u64, challenge: &[u8]) -> bool

Test the nonce and its verifier bytes without changing the puzzle. Acceptance must not depend on evaluation order. challenge must contain exactly Self::challenge_len bytes.

fn solve<E: Fn(&[u8], &mut [u8]) + Clone>(self, evaluate: E) -> Option<u64>

Return the least accepted nonce in 0..=last_nonce(), or None on exhaustion.

fn solve_parallel<E>(self, evaluate: E) -> Option<u64>

where Self: Send, E: Fn(&[u8], &mut [u8]) + Clone + Send,

Return the same least nonce as Self::solve, or None on exhaustion.

impl StructuralPartialEq for FusedPowConfig