bb::crypto::generator_data< Curve > Class Template Reference

class that stores precomputed generators used for Pedersen commitments and Pedersen hashes More...

#include <generator_data.hpp>

Public Types
using	Group = typename Curve::Group
using	AffineElement = typename Curve::AffineElement
using	GeneratorList = std::vector< AffineElement >
using	GeneratorView = std::span< AffineElement const >

Public Member Functions
constexpr	generator_data ()=default
GeneratorView	get (const size_t num_generators, const size_t generator_offset=0, const std::string_view domain_separator=DEFAULT_DOMAIN_SEPARATOR) const

Static Public Member Functions
static generator_data *	get_default_generators ()

Static Public Attributes
static constexpr size_t	DEFAULT_NUM_GENERATORS = 8
static constexpr std::string_view	DEFAULT_DOMAIN_SEPARATOR = "DEFAULT_DOMAIN_SEPARATOR"
static constexpr std::span< const AffineElement >	precomputed_generators
	We precompute and hard-code a small number of generators. For small pedersen commitments + pedersen hashes, this prevents us from having to derive generators at runtime.

Private Attributes
bool	initialized_precomputed_generators = false
std::optional< std::map< std::string, GeneratorList > >	generator_map = {}

Static Private Attributes
static constinit generator_data	default_data = generator_data()

Detailed Description

template<typename Curve>
class bb::crypto::generator_data< Curve >

class that stores precomputed generators used for Pedersen commitments and Pedersen hashes

We create distinct sets of generators via the use of a domain separator. This enables the use of context-specific commitments and hashes. For example, a circuit that generates commitments foo = commit({ a, b }) and bar = commit({c, d}) where foo and bar should not collide.

The goal of generator_data is twofold:

1. Prevent redundant computation of the same generators at runtime (i.e. store in a singleton object)
2. Compute a small number of default generators at compile-time, so that short processes that require a small number of generators do not have to execute the expensive g1::derive_generators method

We store generators in a key:value map, where the key is the domain separator and the value is the vector of associated generators. Pedersen methods take in a pointer to a generator_data object.

generator_data contains a static instantiation of the class: default_data. The intention is for default_data to be used as a singleton class. All Pedersen methods that require a *generator_data parameter (from now on referred to as "generator context") should default to using default_data.

Q: Why make the generator context an input parameter when it defaults to default_data? A: This is not thread-safe. Each process that uses a generator_data object may extend generator_data if more generators are required. i.e. either each process must use an independent generator_data object or the author must KNOW that generator_data will not be extended by any process

Template Parameters

Curve

Definition at line 48 of file generator_data.hpp.

Member Typedef Documentation

AffineElement

template<typename Curve >

using bb::crypto::generator_data< Curve >::AffineElement = typename Curve::AffineElement

Definition at line 51 of file generator_data.hpp.

GeneratorList

template<typename Curve >

using bb::crypto::generator_data< Curve >::GeneratorList = std::vector<AffineElement>

Definition at line 52 of file generator_data.hpp.

GeneratorView

template<typename Curve >

using bb::crypto::generator_data< Curve >::GeneratorView = std::span<AffineElement const>

Definition at line 53 of file generator_data.hpp.

Group

template<typename Curve >

using bb::crypto::generator_data< Curve >::Group = typename Curve::Group

Definition at line 50 of file generator_data.hpp.

Constructor & Destructor Documentation

generator_data()

template<typename Curve >

constexpr bb::crypto::generator_data< Curve >::generator_data ( )

inlineconstexprdefault

Member Function Documentation

get()

template<typename Curve >

GeneratorView bb::crypto::generator_data< Curve >::get ( const size_t  num_generators, const size_t  generator_offset = 0, const std::string_view  domain_separator = DEFAULT_DOMAIN_SEPARATOR  ) const

inline

Definition at line 65 of file generator_data.hpp.

get_default_generators()

template<typename Curve >

static generator_data * bb::crypto::generator_data< Curve >::get_default_generators ( )

inlinestatic

Definition at line 111 of file generator_data.hpp.

Member Data Documentation

default_data

template<typename Curve >

constinit generator_data bb::crypto::generator_data< Curve >::default_data = generator_data()

inlinestaticprivate

Definition at line 115 of file generator_data.hpp.

DEFAULT_DOMAIN_SEPARATOR

template<typename Curve >

constexpr std::string_view bb::crypto::generator_data< Curve >::DEFAULT_DOMAIN_SEPARATOR = "DEFAULT_DOMAIN_SEPARATOR"

inlinestaticconstexpr

Definition at line 55 of file generator_data.hpp.

DEFAULT_NUM_GENERATORS

template<typename Curve >

constexpr size_t bb::crypto::generator_data< Curve >::DEFAULT_NUM_GENERATORS = 8

inlinestaticconstexpr

Definition at line 54 of file generator_data.hpp.

generator_map

template<typename Curve >

std::optional<std::map<std::string, GeneratorList> > bb::crypto::generator_data< Curve >::generator_map = {}

mutableprivate

Definition at line 130 of file generator_data.hpp.

initialized_precomputed_generators

template<typename Curve >

bool bb::crypto::generator_data< Curve >::initialized_precomputed_generators = false

mutableprivate

Definition at line 126 of file generator_data.hpp.

precomputed_generators

template<typename Curve >

constexpr std::span<const AffineElement> bb::crypto::generator_data< Curve >::precomputed_generators

staticconstexpr

Initial value:

=
        get_precomputed_generators<Group, "DEFAULT_DOMAIN_SEPARATOR", DEFAULT_NUM_GENERATORS, 0>()

We precompute and hard-code a small number of generators. For small pedersen commitments + pedersen hashes, this prevents us from having to derive generators at runtime.

Definition at line 62 of file generator_data.hpp.

---

The documentation for this class was generated from the following file:

• src/barretenberg/crypto/generators/generator_data.hpp