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.
type Element struct {
// contains filtered or unexported fields
}
func (v *Element) Absolute(u *Element) *Element
Absolute sets v to |u|, and returns v.
func (v *Element) Add(a, b *Element) *Element
Add sets v = a + b, and returns v.
func (v *Element) Bytes() []byte
Bytes returns the canonical 32-byte little-endian encoding of v.
func (v *Element) Equal(u *Element) int
Equal returns 1 if v and u are equal, and 0 otherwise.
func (v *Element) Invert(z *Element) *Element
Invert sets v = 1/z mod p, and returns v.
If z == 0, Invert returns v = 0.
func (v *Element) IsNegative() int
IsNegative returns 1 if v is negative, and 0 otherwise.
func (v *Element) Mult32(x *Element, y uint32) *Element
Mult32 sets v = x * y, and returns v.
func (v *Element) Multiply(x, y *Element) *Element
Multiply sets v = x * y, and returns v.
func (v *Element) Negate(a *Element) *Element
Negate sets v = -a, and returns v.
func (v *Element) One() *Element
One sets v = 1, and returns v.
func (v *Element) Pow22523(x *Element) *Element
Pow22523 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) *Element
Select sets v to a if cond == 1, and to b if cond == 0.
func (v *Element) Set(a *Element) *Element
Set 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) *Element
Square sets v = x * x, and returns v.
func (v *Element) Subtract(a, b *Element) *Element
Subtract 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() *Element
Zero sets v = 0, and returns v.