package mlsbset

import "github.com/cloudflare/circl/math/mlsbset"

Package mlsbset provides a constant-time exponentiation method with precomputation.

References: "Efficient and secure algorithms for GLV-based scalar multiplication and their implementation on GLV–GLS curves" by (Faz-Hernandez et al.)

• https://doi.org/10.1007/s13389-014-0085-7
• https://eprint.iacr.org/2013/158

Index ¶

• type EltG
• type EltP
• type Encoder
• func New(t, v, w uint) (Encoder, error)
• func (m Encoder) Elts() uint
• func (m Encoder) Encode(k []byte) (*Power, error)
• func (m Encoder) GetParams() Params
• func (m Encoder) IsExtended() bool
• func (m Encoder) Ops() (S uint, M uint)
• func (m Encoder) String() string
• type Group
• type Params
• type Power
• func (p *Power) Digit(v, e uint) (sgn, dig int32)
• func (p *Power) Exp(G Group) EltG
• func (p *Power) String() string

Types ¶

type EltG ¶

type EltG interface{}

EltG is a group element.

type EltP ¶

type EltP interface{}

EltP is a precomputed group element.

type Encoder ¶

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

Encoder allows to convert integers into valid powers.

func New ¶

func New(t, v, w uint) (Encoder, error)

New produces an encoder of the MLSBSet algorithm.

func (Encoder) Elts ¶

func (m Encoder) Elts() uint

Elts returns the total number of elements that must be precomputed.

func (Encoder) Encode ¶

func (m Encoder) Encode(k []byte) (*Power, error)

Encode converts an odd integer k into a valid power for exponentiation.

func (Encoder) GetParams ¶

func (m Encoder) GetParams() Params

GetParams returns the complementary parameters of the encoding.

func (Encoder) IsExtended ¶

func (m Encoder) IsExtended() bool

IsExtended returns true if the element x^(2^(wd)) must be calculated.

func (Encoder) Ops ¶

func (m Encoder) Ops() (S uint, M uint)

Ops returns the number of squares and multiplications executed during an exponentiation.

func (Encoder) String ¶

func (m Encoder) String() string

type Group ¶

type Group interface {
	Identity() EltG                    // Returns the identity of the group.
	Sqr(x EltG)                        // Calculates x = x^2.
	Mul(x EltG, y EltP)                // Calculates x = x*y.
	NewEltP() EltP                     // Returns an arbitrary precomputed element.
	ExtendedEltP() EltP                // Returns the precomputed element x^(2^(w*d)).
	Lookup(a EltP, v uint, s, u int32) // Sets a = s*T[v][u].
}

Group defines the operations required by MLSBSet exponentiation method.

type Params ¶

type Params struct {
	T uint // T is the maximum size (in bits) of exponents.
	V uint // V is the number of tables.
	W uint // W is the window size.
	E uint // E is the number of digits per table.
	D uint // D is the number of digits in total.
	L uint // L is the length of the code.
}

Params contains the parameters of the encoding.

type Power ¶

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

Power is a valid exponent produced by the MLSBSet encoding algorithm.

func (*Power) Digit ¶

func (p *Power) Digit(v, e uint) (sgn, dig int32)

Digit returns the (v,e)-th digit and its sign.

func (*Power) Exp ¶

func (p *Power) Exp(G Group) EltG

Exp is calculates x^k, where x is a predetermined element of a group G.

func (*Power) String ¶

func (p *Power) String() string

Source Files ¶

mlsbset.go power.go