fss::GrottoDcf< in_bits, Prg, In, par_depth > Class Template Reference

2-party DCF scheme over F2 from standard DPF (Grotto construction). More...

Classes
struct	ParityTree
	Parity segment tree over leaf control bits. More...

Public Types
using	Cw = typename DpfType::Cw

Public Member Functions
void	Gen (Cw cws[], const int4 s0s[2], In a)
	Key generation method.
void	Preprocess (ParityTree &pt, int4 s0, const Cw cws[])
	Preprocess: expand DPF tree and build parity segment tree.
void	EvalAll (bool b, int4 s0, const Cw cws[], bool ys[])
	Full domain evaluation.

Static Public Member Functions
static bool	Eval (const ParityTree &pt, In x)
	Prefix-parity query on the parity segment tree.

Public Attributes
Prg	prg

Detailed Description

template<int in_bits, typename Prg, typename In = uint, int par_depth = -1>
requires ((std::is_unsigned_v<In> || std::is_same_v<In, __uint128_t>) && in_bits <= sizeof(In) * 8 && Prgable<Prg, 2>)
class fss::GrottoDcf< in_bits, Prg, In, par_depth >

2-party DCF scheme over F2 from standard DPF (Grotto construction).

Template Parameters

in_bits	Input domain bit size.
Prg	See Prgable. Must satisfy Prgable<Prg, 2> (same as DPF).
In	Type for the input domain. From uint8_t to __uint128_t.
par_depth	-1 is to use ceil(log(num of threads)). Only Preprocess() and EvalAll() use it.

Member Function Documentation

Eval()

template<int in_bits, typename Prg , typename In = uint, int par_depth = -1>

static bool fss::GrottoDcf< in_bits, Prg, In, par_depth >::Eval ( const ParityTree &  pt, In  x  )

inlinestatic

Prefix-parity query on the parity segment tree.

Returns party b's share of 1[alpha <= x]. Internally queries endpoint e = x + 1, computing prefix-parity of [0, e).

Parameters

pt	ParityTree from Preprocess().
x	Query point.

Returns

bool share such that share_0 XOR share_1 = 1[alpha <= x].

EvalAll()

template<int in_bits, typename Prg , typename In = uint, int par_depth = -1>

void fss::GrottoDcf< in_bits, Prg, In, par_depth >::EvalAll ( bool  b, int4  s0, const Cw  cws[], bool  ys[]  )

inline

Full domain evaluation.

Computes party b's share of 1[alpha <= x] for all x in [0, N).

Phase 1: O(N) PRG calls to expand the tree. Phase 2b: O(N) prefix-sum (running XOR) over leaf control bits.

Parameters

b	Party index.
s0	Initial seed of the party.
cws	Correction words from Gen().
ys	Pre-allocated output array of size N = 2^in_bits. ys[x] = party b's share of 1[alpha <= x].

Gen()

template<int in_bits, typename Prg , typename In = uint, int par_depth = -1>

void fss::GrottoDcf< in_bits, Prg, In, par_depth >::Gen ( Cw  cws[], const int4  s0s[2], In  a  )

inline

Key generation method.

Delegates to Dpf::Gen with beta=0.

Parameters

cws	Pre-allocated array of Cw. Size must be in_bits + 1.
s0s	2 initial seeds. Users can randomly sample them.
a	The secret comparison threshold.

The key for party i consists of cws + s0s[i].

Preprocess()

template<int in_bits, typename Prg , typename In = uint, int par_depth = -1>

void fss::GrottoDcf< in_bits, Prg, In, par_depth >::Preprocess ( ParityTree &  pt, int4  s0, const Cw  cws[]  )

inline

Preprocess: expand DPF tree and build parity segment tree.

Phase 1: O(N) PRG calls to expand the tree and extract leaf control bits. Phase 2a: O(N) XOR operations to build the parity segment tree bottom-up.

Parameters

pt	ParityTree with p pre-allocated to size 2*N-1 where N = 2^in_bits. pt.b must be set to the party index before calling.
s0	Initial seed of the party.
cws	Correction words from Gen().

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

• include/fss/grotto_dcf.cuh