mirror of
https://github.com/tailscale/tailscale.git
synced 2024-12-05 16:05:36 +00:00
f50043f6cb
Following the pattern elsewhere, we create a new tka-specific types package for the types that need to couple between the serialized structure types, and tka. Signed-off-by: Tom DNetto <tom@tailscale.com>
101 lines
2.8 KiB
Go
101 lines
2.8 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 tka
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto/ed25519"
|
|
"errors"
|
|
"fmt"
|
|
|
|
"github.com/fxamacker/cbor/v2"
|
|
"github.com/hdevalence/ed25519consensus"
|
|
"golang.org/x/crypto/blake2s"
|
|
"tailscale.com/types/tkatype"
|
|
)
|
|
|
|
// SigKind describes valid NodeKeySignature types.
|
|
type SigKind uint8
|
|
|
|
const (
|
|
SigInvalid SigKind = iota
|
|
// SigDirect describes a signature over a specific node key, using
|
|
// the keyID specified.
|
|
SigDirect
|
|
)
|
|
|
|
func (s SigKind) String() string {
|
|
switch s {
|
|
case SigInvalid:
|
|
return "invalid"
|
|
case SigDirect:
|
|
return "direct"
|
|
default:
|
|
return fmt.Sprintf("Sig?<%d>", int(s))
|
|
}
|
|
}
|
|
|
|
// NodeKeySignature encapsulates a signature that authorizes a specific
|
|
// node key, based on verification from keys in the tailnet key authority.
|
|
type NodeKeySignature struct {
|
|
// SigKind identifies the variety of signature.
|
|
SigKind SigKind `cbor:"1,keyasint"`
|
|
// Pubkey identifies the public key which is being certified.
|
|
Pubkey []byte `cbor:"2,keyasint"`
|
|
|
|
// KeyID identifies which key in the tailnet key authority should
|
|
// be used to verify this signature. Only set for SigDirect and
|
|
// SigCredential signature kinds.
|
|
KeyID []byte `cbor:"3,keyasint,omitempty"`
|
|
|
|
// Signature is the packed (R, S) ed25519 signature over the rest
|
|
// of the structure.
|
|
Signature []byte `cbor:"4,keyasint,omitempty"`
|
|
}
|
|
|
|
// sigHash returns the cryptographic digest which a signature
|
|
// is over.
|
|
//
|
|
// This is a hash of the serialized structure, sans the signature.
|
|
// Without this exclusion, the hash used for the signature
|
|
// would be circularly dependent on the signature.
|
|
func (s NodeKeySignature) sigHash() [blake2s.Size]byte {
|
|
dupe := s
|
|
dupe.Signature = nil
|
|
return blake2s.Sum256(dupe.Serialize())
|
|
}
|
|
|
|
// Serialize returns the given NKS in a serialized format.
|
|
func (s *NodeKeySignature) Serialize() tkatype.MarshaledSignature {
|
|
out := bytes.NewBuffer(make([]byte, 0, 128)) // 64byte sig + 32byte keyID + 32byte headroom
|
|
encoder, err := cbor.CTAP2EncOptions().EncMode()
|
|
if err != nil {
|
|
// Deterministic validation of encoding options, should
|
|
// never fail.
|
|
panic(err)
|
|
}
|
|
if err := encoder.NewEncoder(out).Encode(s); err != nil {
|
|
// Writing to a bytes.Buffer should never fail.
|
|
panic(err)
|
|
}
|
|
return out.Bytes()
|
|
}
|
|
|
|
// verifySignature checks that the NodeKeySignature is authentic and certified
|
|
// by the given verificationKey.
|
|
func (s *NodeKeySignature) verifySignature(verificationKey Key) error {
|
|
sigHash := s.sigHash()
|
|
switch verificationKey.Kind {
|
|
case Key25519:
|
|
if ed25519consensus.Verify(ed25519.PublicKey(verificationKey.Public), sigHash[:], s.Signature) {
|
|
return nil
|
|
}
|
|
return errors.New("invalid signature")
|
|
|
|
default:
|
|
return fmt.Errorf("unhandled key type: %v", verificationKey.Kind)
|
|
}
|
|
}
|