Package field implements fast arithmetic modulo 2^255-19.
type Element struct {
// contains filtered or unexported fields
}Element represents an element of the field GF(2^255-19). Note that this is not a cryptographically secure group, and should only be used to interact with edwards25519.Point coordinates.
This type works similarly to math/big.Int, and all arguments and receivers are allowed to alias.
The zero value is a valid zero element.
func (v *Element) Absolute(u *Element) *ElementAbsolute sets v to |u|, and returns v.
func (v *Element) Add(a, b *Element) *ElementAdd sets v = a + b, and returns v.
func (v *Element) Bytes() []byteBytes returns the canonical 32-byte little-endian encoding of v.
func (v *Element) Equal(u *Element) intEqual returns 1 if v and u are equal, and 0 otherwise.
func (v *Element) Invert(z *Element) *ElementInvert sets v = 1/z mod p, and returns v.
If z == 0, Invert returns v = 0.
func (v *Element) IsNegative() intIsNegative returns 1 if v is negative, and 0 otherwise.
func (v *Element) Mult32(x *Element, y uint32) *ElementMult32 sets v = x * y, and returns v.
func (v *Element) Multiply(x, y *Element) *ElementMultiply sets v = x * y, and returns v.
func (v *Element) Negate(a *Element) *ElementNegate sets v = -a, and returns v.
func (v *Element) One() *ElementOne sets v = 1, and returns v.
func (v *Element) Pow22523(x *Element) *ElementPow22523 set v = x^((p-5)/8), and returns v. (p-5)/8 is 2^252-3.
func (v *Element) Select(a, b *Element, cond int) *ElementSelect sets v to a if cond == 1, and to b if cond == 0.
func (v *Element) Set(a *Element) *ElementSet sets v = a, and returns v.
func (v *Element) SetBytes(x []byte) (*Element, error)SetBytes sets v to x, where x is a 32-byte little-endian encoding. If x is not of the right length, SetBytes returns nil and an error, and the receiver is unchanged.
Consistent with RFC 7748, the most significant bit (the high bit of the last byte) is ignored, and non-canonical values (2^255-19 through 2^255-1) are accepted. Note that this is laxer than specified by RFC 8032, but consistent with most Ed25519 implementations.
func (r *Element) SqrtRatio(u, v *Element) (R *Element, wasSquare int)SqrtRatio sets r to the non-negative square root of the ratio of u and v.
If u/v is square, SqrtRatio returns r and 1. If u/v is not square, SqrtRatio sets r according to Section 4.3 of draft-irtf-cfrg-ristretto255-decaf448-00, and returns r and 0.
func (v *Element) Square(x *Element) *ElementSquare sets v = x * x, and returns v.
func (v *Element) Subtract(a, b *Element) *ElementSubtract sets v = a - b, and returns v.
func (v *Element) Swap(u *Element, cond int)Swap swaps v and u if cond == 1 or leaves them unchanged if cond == 0, and returns v.
func (v *Element) Zero() *ElementZero sets v = 0, and returns v.