sign

Documentation

Overview

Package sign contains useful tools for the different signing algorithms.

Index

• type AggregatableScheme
• type CompletePolicy
  • func (p CompletePolicy) Check(m ParticipationMask) bool
• type Mask
  • func NewMask(suite pairing.Suite, publics []kyber.Point, myKey kyber.Point) (*Mask, error)
  • func (m *Mask) CountEnabled() int
  • func (m *Mask) CountTotal() int
  • func (m *Mask) IndexOfNthEnabled(nth int) int
  • func (m *Mask) Len() int
  • func (m *Mask) Mask() []byte
  • func (m *Mask) Merge(mask []byte) error
  • func (m *Mask) NthEnabledAtIndex(idx int) int
  • func (m *Mask) Participants() []kyber.Point
  • func (m *Mask) Publics() []kyber.Point
  • func (m *Mask) SetBit(i int, enable bool) error
  • func (m *Mask) SetMask(mask []byte) error
• type ParticipationMask
• type Policy
• type Scheme
• type ThresholdPolicy
  • func NewThresholdPolicy(thold int) *ThresholdPolicy
  • func (p ThresholdPolicy) Check(m ParticipationMask) bool
• type ThresholdScheme

Types

type AggregatableScheme

type AggregatableScheme interface {
	Scheme
	AggregateSignatures(sigs ...[]byte) ([]byte, error)
	AggregatePublicKeys(Xs ...kyber.Point) kyber.Point
}

AggregatableScheme is an interface allowing to aggregate signatures and public keys to efficient verification.

type CompletePolicy

type CompletePolicy struct {
}

CompletePolicy is the default policy requiring that all participants have cosigned to make a collective signature valid.

func (CompletePolicy) Check

func (p CompletePolicy) Check(m ParticipationMask) bool

Check verifies that all participants have contributed to a collective signature.

type Mask

type Mask struct {
	// contains filtered or unexported fields
}

Mask is a bitmask of the participation to a collective signature.

func NewMask

func NewMask(suite pairing.Suite, publics []kyber.Point, myKey kyber.Point) (*Mask, error)

NewMask creates a new mask from a list of public keys. If a key is provided, it will set the bit of the key to 1 or return an error if it is not found.

func (*Mask) CountEnabled

func (m *Mask) CountEnabled() int

CountEnabled returns the number of bit set to 1

func (*Mask) CountTotal

func (m *Mask) CountTotal() int

CountTotal returns the number of potential participants

func (*Mask) IndexOfNthEnabled

func (m *Mask) IndexOfNthEnabled(nth int) int

IndexOfNthEnabled returns the index of the nth enabled bit or -1 if out of bounds.

func (*Mask) Len

func (m *Mask) Len() int

Len returns the length of the byte array necessary to store the bitmask.

func (*Mask) Mask

func (m *Mask) Mask() []byte

Mask returns the bitmask as a byte array.

func (*Mask) Merge

func (m *Mask) Merge(mask []byte) error

Merge merges the given mask to the current one only if the length matches

func (*Mask) NthEnabledAtIndex

func (m *Mask) NthEnabledAtIndex(idx int) int

NthEnabledAtIndex returns the sum of bits set to 1 until the given index. In other words, it returns how many bits are enabled before the given index.

func (*Mask) Participants

func (m *Mask) Participants() []kyber.Point

Participants returns the list of public keys participating.

func (*Mask) Publics

func (m *Mask) Publics() []kyber.Point

Publics returns a copy of the list of public keys.

func (*Mask) SetBit

func (m *Mask) SetBit(i int, enable bool) error

SetBit turns on or off the bit at the given index.

func (*Mask) SetMask

func (m *Mask) SetMask(mask []byte) error

SetMask replaces the current mask by the new one if the length matches.

type ParticipationMask

type ParticipationMask interface {
	// CountEnabled returns the number of participants
	CountEnabled() int
	// CountTotal returns the number of candidates
	CountTotal() int
}

ParticipationMask is an interface to get the total number of candidates and the number of participants.

type Policy

type Policy interface {
	Check(m ParticipationMask) bool
}

Policy represents a fully customizable cosigning policy deciding what cosigner sets are and aren't sufficient for a collective signature to be considered acceptable to a verifier. The Check method may inspect the set of participants that cosigned by invoking cosi.Mask and/or cosi.MaskBit, and may use any other relevant contextual information (e.g., how security-critical the operation relying on the collective signature is) in determining whether the collective signature was produced by an acceptable set of cosigners.

type Scheme

type Scheme interface {
	NewKeyPair(random cipher.Stream) (kyber.Scalar, kyber.Point)
	Sign(private kyber.Scalar, msg []byte) ([]byte, error)
	Verify(public kyber.Point, msg, sig []byte) error
}

Scheme is the minimal interface for a signature scheme. Implemented by BLS and TBLS

type ThresholdPolicy

type ThresholdPolicy struct {
	// contains filtered or unexported fields
}

ThresholdPolicy allows to specify a simple t-of-n policy requring that at least the given threshold number of participants t have cosigned to make a collective signature valid.

func NewThresholdPolicy

func NewThresholdPolicy(thold int) *ThresholdPolicy

NewThresholdPolicy returns a new ThresholdPolicy with the given threshold.

func (ThresholdPolicy) Check

func (p ThresholdPolicy) Check(m ParticipationMask) bool

Check verifies that at least a threshold number of participants have contributed to a collective signature.

type ThresholdScheme

type ThresholdScheme interface {
	Sign(private *share.PriShare, msg []byte) ([]byte, error)
	IndexOf(signature []byte) (int, error)
	Recover(public *share.PubPoly, msg []byte, sigs [][]byte, t, n int) ([]byte, error)
	VerifyPartial(public *share.PubPoly, msg, sig []byte) error
	VerifyRecovered(public kyber.Point, msg, sig []byte) error
}

ThresholdScheme is a threshold signature scheme that issues partial signatures and can recover a "full" signature. It is implemented by the tbls package. TODO: see any potential conflict or synergy with mask and policy