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// Copyright 2022 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.
//go:build go1.20
package curve25519
import "crypto/ecdh"
func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
curve := ecdh.X25519()
pub, err := curve.NewPublicKey(point)
if err != nil {
return nil, err
}
priv, err := curve.NewPrivateKey(scalar)
if err != nil {
return nil, err
}
out, err := priv.ECDH(pub)
if err != nil {
return nil, err
}
copy(dst[:], out)
return dst[:], nil
}
func scalarMult(dst, scalar, point *[32]byte) {
if _, err := x25519(dst, scalar[:], point[:]); err != nil {
// The only error condition for x25519 when the inputs are 32 bytes long
// is if the output would have been the all-zero value.
for i := range dst {
dst[i] = 0
}
}
}
func scalarBaseMult(dst, scalar *[32]byte) {
curve := ecdh.X25519()
priv, err := curve.NewPrivateKey(scalar[:])
if err != nil {
panic("curve25519: internal error: scalarBaseMult was not 32 bytes")
}
copy(dst[:], priv.PublicKey().Bytes())
}
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