podman
59 строк · 2.1 Кб
1// Copyright 2019 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package curve25519 provides an implementation of the X25519 function, which
6// performs scalar multiplication on the elliptic curve known as Curve25519.
7// See RFC 7748.
8//
9// Starting in Go 1.20, this package is a wrapper for the X25519 implementation
10// in the crypto/ecdh package.
11package curve25519 // import "golang.org/x/crypto/curve25519"
12
13// ScalarMult sets dst to the product scalar * point.
14//
15// Deprecated: when provided a low-order point, ScalarMult will set dst to all
16// zeroes, irrespective of the scalar. Instead, use the X25519 function, which
17// will return an error.
18func ScalarMult(dst, scalar, point *[32]byte) {
19scalarMult(dst, scalar, point)
20}
21
22// ScalarBaseMult sets dst to the product scalar * base where base is the
23// standard generator.
24//
25// It is recommended to use the X25519 function with Basepoint instead, as
26// copying into fixed size arrays can lead to unexpected bugs.
27func ScalarBaseMult(dst, scalar *[32]byte) {
28scalarBaseMult(dst, scalar)
29}
30
31const (
32// ScalarSize is the size of the scalar input to X25519.
33ScalarSize = 32
34// PointSize is the size of the point input to X25519.
35PointSize = 32
36)
37
38// Basepoint is the canonical Curve25519 generator.
39var Basepoint []byte
40
41var basePoint = [32]byte{9}
42
43func init() { Basepoint = basePoint[:] }
44
45// X25519 returns the result of the scalar multiplication (scalar * point),
46// according to RFC 7748, Section 5. scalar, point and the return value are
47// slices of 32 bytes.
48//
49// scalar can be generated at random, for example with crypto/rand. point should
50// be either Basepoint or the output of another X25519 call.
51//
52// If point is Basepoint (but not if it's a different slice with the same
53// contents) a precomputed implementation might be used for performance.
54func X25519(scalar, point []byte) ([]byte, error) {
55// Outline the body of function, to let the allocation be inlined in the
56// caller, and possibly avoid escaping to the heap.
57var dst [32]byte
58return x25519(&dst, scalar, point)
59}
60