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dkg/gennaro/participant.go

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+//
+// Copyright Coinbase, Inc. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// Package gennaro is an implementation of the DKG part of https://eprint.iacr.org/2020/540.pdf
+package gennaro
+
+import (
+	"crypto/elliptic"
+	"fmt"
+
+	"github.com/sonr-io/sonr/crypto/core/curves"
+	"github.com/sonr-io/sonr/crypto/internal"
+	v1 "github.com/sonr-io/sonr/crypto/sharing/v1"
+)
+
+// Participant is a DKG player that contains information needed to perform DKG rounds
+// and yield a secret key share and public key when finished
+type Participant struct {
+	round                  int
+	curve                  elliptic.Curve
+	scalar                 curves.EcScalar
+	otherParticipantShares map[uint32]*dkgParticipantData
+	id                     uint32
+	skShare                *curves.Element
+	verificationKey        *v1.ShareVerifier
+	feldman                *v1.Feldman
+	pedersen               *v1.Pedersen
+	pedersenResult         *v1.PedersenResult
+}
+
+// NewParticipant creates a participant ready to perform a DKG
+// `id` is the integer value identifier for this participant
+// `threshold` is the minimum bound for the secret sharing scheme
+// `generator` is the blinding factor generator used by pedersen's verifiable secret sharing
+// `otherParticipants` is the integer value identifiers for the other participants
+// `id` and `otherParticipants` must be the set of integers 1,2,....,n
+func NewParticipant(
+	id, threshold uint32,
+	generator *curves.EcPoint,
+	scalar curves.EcScalar,
+	otherParticipants ...uint32,
+) (*Participant, error) {
+	if generator == nil || len(otherParticipants) == 0 {
+		return nil, internal.ErrNilArguments
+	}
+	err := validIds(append(otherParticipants, id))
+	if err != nil {
+		return nil, err
+	}
+
+	limit := uint32(len(otherParticipants)) + 1
+	feldman, err := v1.NewFeldman(threshold, limit, generator.Curve)
+	if err != nil {
+		return nil, err
+	}
+	pedersen, err := v1.NewPedersen(threshold, limit, generator)
+	if err != nil {
+		return nil, err
+	}
+
+	otherParticipantShares := make(map[uint32]*dkgParticipantData, len(otherParticipants))
+	for _, id := range otherParticipants {
+		otherParticipantShares[id] = &dkgParticipantData{
+			Id: id,
+		}
+	}
+
+	return &Participant{
+		id:                     id,
+		round:                  1,
+		curve:                  generator.Curve,
+		scalar:                 scalar,
+		feldman:                feldman,
+		pedersen:               pedersen,
+		otherParticipantShares: otherParticipantShares,
+	}, nil
+}
+
+// Determines if the SSIDs are exactly the values 1..n.
+func validIds(ids []uint32) error {
+	// Index
+	idMap := make(map[uint32]bool, len(ids))
+	for _, id := range ids {
+		idMap[id] = true
+	}
+	// Check
+	for i := 1; i <= len(ids); i++ {
+		if ok := idMap[uint32(i)]; !ok {
+			return fmt.Errorf("the ID list %v is invalid; values must be 1,2,..,n", ids)
+		}
+	}
+	return nil
+}
+
+type dkgParticipantData struct {
+	Id        uint32
+	Share     *v1.ShamirShare
+	Verifiers []*v1.ShareVerifier
+}