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tailscale/types/key/nl.go

128 lines
3.5 KiB
Go

// Copyright (c) 2022 Tailscale Inc & 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 key
import (
"crypto/ed25519"
"crypto/subtle"
"go4.org/mem"
"tailscale.com/types/structs"
"tailscale.com/types/tkatype"
)
const (
// nlPrivateHexPrefix is the prefix used to identify a
// hex-encoded network-lock key.
nlPrivateHexPrefix = "nlpriv:"
// nlPublicHexPrefix is the prefix used to identify the public
// side of a hex-encoded network-lock key.
nlPublicHexPrefix = "nlpub:"
)
// NLPrivate is a node-managed network-lock key, used for signing
// node-key signatures and authority update messages.
type NLPrivate struct {
_ structs.Incomparable // because == isn't constant-time
k [ed25519.PrivateKeySize]byte
}
// IsZero reports whether k is the zero value.
func (k NLPrivate) IsZero() bool {
empty := NLPrivate{}
return subtle.ConstantTimeCompare(k.k[:], empty.k[:]) == 1
}
// NewNLPrivate creates and returns a new network-lock key.
func NewNLPrivate() NLPrivate {
// ed25519.GenerateKey 'clamps' the key, not that it
// matters given we don't do Diffie-Hellman.
_, priv, err := ed25519.GenerateKey(nil) // nil == crypto/rand
if err != nil {
panic(err)
}
var out NLPrivate
copy(out.k[:], priv)
return out
}
// MarshalText implements encoding.TextUnmarshaler.
func (k *NLPrivate) UnmarshalText(b []byte) error {
return parseHex(k.k[:], mem.B(b), mem.S(nlPrivateHexPrefix))
}
// MarshalText implements encoding.TextMarshaler.
func (k NLPrivate) MarshalText() ([]byte, error) {
return toHex(k.k[:], nlPrivateHexPrefix), nil
}
// Public returns the public component of this key.
func (k NLPrivate) Public() NLPublic {
var out NLPublic
copy(out.k[:], ed25519.PrivateKey(k.k[:]).Public().(ed25519.PublicKey))
return out
}
// KeyID returns an identifier for this key.
func (k NLPrivate) KeyID() tkatype.KeyID {
// The correct way to compute this is:
// return tka.Key{
// Kind: tka.Key25519,
// Public: pub.k[:],
// }.ID()
//
// However, under the hood the key id for a 25519
// key is just the public key, so we avoid the
// dependency on tka by just doing this ourselves.
pub := k.Public().k
return pub[:]
}
// SignAUM implements tka.Signer.
func (k NLPrivate) SignAUM(sigHash tkatype.AUMSigHash) ([]tkatype.Signature, error) {
return []tkatype.Signature{{
KeyID: k.KeyID(),
Signature: ed25519.Sign(ed25519.PrivateKey(k.k[:]), sigHash[:]),
}}, nil
}
// SignNKS signs the tka.NodeKeySignature identified by sigHash.
func (k NLPrivate) SignNKS(sigHash tkatype.NKSSigHash) ([]byte, error) {
return ed25519.Sign(ed25519.PrivateKey(k.k[:]), sigHash[:]), nil
}
// NLPublic is the public portion of a a NLPrivate.
type NLPublic struct {
k [ed25519.PublicKeySize]byte
}
// MarshalText implements encoding.TextUnmarshaler.
func (k *NLPublic) UnmarshalText(b []byte) error {
return parseHex(k.k[:], mem.B(b), mem.S(nlPublicHexPrefix))
}
// MarshalText implements encoding.TextMarshaler.
func (k NLPublic) MarshalText() ([]byte, error) {
return toHex(k.k[:], nlPublicHexPrefix), nil
}
// Verifier returns a ed25519.PublicKey that can be used to
// verify signatures.
func (k NLPublic) Verifier() ed25519.PublicKey {
return ed25519.PublicKey(k.k[:])
}
// IsZero reports whether k is the zero value.
func (k NLPublic) IsZero() bool {
return k.Equal(NLPublic{})
}
// Equal reports whether k and other are the same key.
func (k NLPublic) Equal(other NLPublic) bool {
return subtle.ConstantTimeCompare(k.k[:], other.k[:]) == 1
}