Copyright 2019 The Go Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
Package curve25519 provides an implementation of the X25519 function, which performs scalar multiplication on the elliptic curve known as Curve25519. See RFC 7748.
package curve25519 // import "golang.org/x/crypto/curve25519"

import (
	
	
)
ScalarMult sets dst to the product scalar * point. Deprecated: when provided a low-order point, ScalarMult will set dst to all zeroes, irrespective of the scalar. Instead, use the X25519 function, which will return an error.
func (, ,  *[32]byte) {
	scalarMult(, , )
}
ScalarBaseMult sets dst to the product scalar * base where base is the standard generator. It is recommended to use the X25519 function with Basepoint instead, as copying into fixed size arrays can lead to unexpected bugs.
func (,  *[32]byte) {
	ScalarMult(, , &basePoint)
}
ScalarSize is the size of the scalar input to X25519.
PointSize is the size of the point input to X25519.
	PointSize = 32
)
Basepoint is the canonical Curve25519 generator.
var Basepoint []byte

var basePoint = [32]byte{9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

func () { Basepoint = basePoint[:] }

func () {
	if subtle.ConstantTimeCompare(Basepoint, []byte{
		0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	}) != 1 {
		panic("curve25519: global Basepoint value was modified")
	}
}
X25519 returns the result of the scalar multiplication (scalar * point), according to RFC 7748, Section 5. scalar, point and the return value are slices of 32 bytes. scalar can be generated at random, for example with crypto/rand. point should be either Basepoint or the output of another X25519 call. If point is Basepoint (but not if it's a different slice with the same contents) a precomputed implementation might be used for performance.
Outline the body of function, to let the allocation be inlined in the caller, and possibly avoid escaping to the heap.
	var  [32]byte
	return x25519(&, , )
}

func ( *[32]byte, ,  []byte) ([]byte, error) {
	var  [32]byte
	if  := len();  != 32 {
		return nil, fmt.Errorf("bad scalar length: %d, expected %d", , 32)
	}
	if  := len();  != 32 {
		return nil, fmt.Errorf("bad point length: %d, expected %d", , 32)
	}
	copy([:], )
	if &[0] == &Basepoint[0] {
		checkBasepoint()
		ScalarBaseMult(, &)
	} else {
		var ,  [32]byte
		copy([:], )
		ScalarMult(, &, &)
		if subtle.ConstantTimeCompare([:], [:]) == 1 {
			return nil, fmt.Errorf("bad input point: low order point")
		}
	}
	return [:], nil