Struct BHP 

pub struct BHP<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> { /* private fields */ }

BHP is a collision-resistant hash function that takes a variable-length input. The BHP hash function does not behave like a random oracle, see Poseidon for one.

Design

The BHP hash function splits the given input into blocks, and processes them iteratively.

The first iteration is initialized as follows:

DIGEST_0 = BHP([ 0...0 || DOMAIN || LENGTH(INPUT) || INPUT[0..BLOCK_SIZE] ]);

Each subsequent iteration is initialized as follows:

DIGEST_N+1 = BHP([ DIGEST_N[0..DATA_BITS] || INPUT[(N+1)*BLOCK_SIZE..(N+2)*BLOCK_SIZE] ]);

Implementations

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> BHP<E, NUM_WINDOWS, WINDOW_SIZE>

pub fn setup(domain: &str) -> Result<Self>

Initializes a new instance of BHP with the given domain.

pub fn domain(&self) -> &[bool]

Returns the domain separator for the BHP hash function.

pub fn merkle_empty_hash(&self) -> Result<Field<E>>

Returns the Merkle empty hash of this instance, computing it on first use.

This is PathHash::hash_children(0, 0) from snarkvm-console-collections, and test_cached_empty_hash_matches_the_computed_one checks that the two agree. The hash depends on the domain and bases, so it is cached per instance, not per type.

pub fn bases(&self) -> &Arc<Vec<Vec<Group<E>>>>

Returns the bases.

pub fn random_base(&self) -> &Arc<Vec<Group<E>>>

Returns the random base window.

pub fn num_windows(&self) -> u8

Returns the number of windows.

pub fn window_size(&self) -> u8

Returns the window size.

Trait Implementations

impl<E: Clone + Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Clone for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Commit for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

fn commit( &self, input: &[Self::Input], randomizer: &Self::Randomizer, ) -> Result<Self::Output>

Returns the BHP commitment of the given input and randomizer as a field element.

type Input = bool

type Output = Field<E>

type Randomizer = Scalar<E>

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> CommitUncompressed for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

fn commit_uncompressed( &self, input: &[Self::Input], randomizer: &Self::Randomizer, ) -> Result<Self::Output>

Returns the BHP commitment of the given input and randomizer as an affine group element.

type Input = bool

type Output = Group<E>

type Randomizer = Scalar<E>

impl<E: Debug + Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Debug for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

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

Formats the value using the given formatter.

impl<'de, E, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Deserialize<'de> for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

where E: Serialize + DeserializeOwned + Environment,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Hash for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

fn hash(&self, input: &[Self::Input]) -> Result<Self::Output>

Returns the BHP hash of the given input as a field element.

type Input = bool

type Output = Field<E>

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> HashUncompressed for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

fn hash_uncompressed(&self, input: &[Self::Input]) -> Result<Self::Output>

Returns the BHP hash of the given input as an affine group element.

This uncompressed variant of the BHP hash function is provided to support the BHP commitment scheme, as it is typically not used by applications.

type Input = bool

type Output = Group<E>

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> PartialEq for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

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

Ignores the cached empty hash, which is derived from the domain and bases.

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

Inequality operator !=.

impl<E, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> Serialize for BHP<E, NUM_WINDOWS, WINDOW_SIZE>

where E: Serialize + DeserializeOwned + Environment,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.