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// This file is part of gnunet-go, a GNUnet-implementation in Golang.
// Copyright (C) 2019-2022 Bernd Fix >Y<
//
// gnunet-go is free software: you can redistribute it and/or modify it
// under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// gnunet-go is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// SPDX-License-Identifier: AGPL3.0-or-later
package message
import (
//"encoding/hex"
"fmt"
"time"
"gnunet/crypto"
"gnunet/enums"
"gnunet/util"
"github.com/bfix/gospel/crypto/ed25519"
"github.com/bfix/gospel/data"
)
// EphKeyBlock defines the layout of signed ephemeral key with attributes.
type EphKeyBlock struct {
Purpose *crypto.SignaturePurpose // signature purpose: SIG_ECC_KEY
CreateTime util.AbsoluteTime // Time of key creation
ExpireTime util.RelativeTime // Time to live for key
EphemeralKey []byte `size:"32"` // Ephemeral EdDSA public key
PeerID *util.PeerID // Peer identity (EdDSA public key)
}
// EphemeralKeyMsg announces a new transient key for a peer. The key is signed
// by the issuing peer.
type EphemeralKeyMsg struct {
MsgSize uint16 `order:"big"` // total size of message
MsgType uint16 `order:"big"` // CORE_EPHEMERAL_KEY (88)
SenderStatus uint32 `order:"big"` // enum PeerStateMachine
Signature []byte `size:"64"` // EdDSA signature
SignedBlock *EphKeyBlock
}
// NewEphemeralKeyMsg creates an empty message for key announcement.
func NewEphemeralKeyMsg() *EphemeralKeyMsg {
return &EphemeralKeyMsg{
MsgSize: 160,
MsgType: CORE_EPHEMERAL_KEY,
SenderStatus: 1,
Signature: make([]byte, 64),
SignedBlock: &EphKeyBlock{
Purpose: &crypto.SignaturePurpose{
Size: 88,
Purpose: uint32(enums.SIG_SET_ECC_KEY),
},
CreateTime: util.AbsoluteTimeNow(),
ExpireTime: util.NewRelativeTime(12 * time.Hour),
EphemeralKey: make([]byte, 32),
PeerID: util.NewPeerID(nil),
},
}
}
// String returns a human-readable representation of the message.
func (m *EphemeralKeyMsg) String() string {
return fmt.Sprintf("EphKeyMsg{peer=%s,ephkey=%s,create=%s,expire=%s,status=%d}",
util.EncodeBinaryToString(m.SignedBlock.PeerID.Key),
util.EncodeBinaryToString(m.SignedBlock.EphemeralKey),
m.SignedBlock.CreateTime, m.SignedBlock.ExpireTime,
m.SenderStatus)
}
// Header returns the message header in a separate instance.
func (m *EphemeralKeyMsg) Header() *Header {
return &Header{m.MsgSize, m.MsgType}
}
// Public extracts the public key of an announcing peer.
func (m *EphemeralKeyMsg) Public() *ed25519.PublicKey {
return m.SignedBlock.PeerID.PublicKey()
}
// Verify the integrity of the message data using the public key of the
// announcing peer.
func (m *EphemeralKeyMsg) Verify(pub *ed25519.PublicKey) (bool, error) {
data, err := data.Marshal(m.SignedBlock)
if err != nil {
return false, err
}
sig, err := ed25519.NewEdSignatureFromBytes(m.Signature)
if err != nil {
return false, err
}
return pub.EdVerify(data, sig)
}
// NewEphemeralKey creates a new ephemeral key signed by a long-term private
// key and the corresponding GNUnet message to announce the new key.
func NewEphemeralKey(peerID []byte, ltPrv *ed25519.PrivateKey) (*ed25519.PrivateKey, *EphemeralKeyMsg, error) {
msg := NewEphemeralKeyMsg()
copy(msg.SignedBlock.PeerID.Key, peerID)
seed := util.NewRndArray(32)
prv := ed25519.NewPrivateKeyFromSeed(seed)
copy(msg.SignedBlock.EphemeralKey, prv.Public().Bytes())
data, err := data.Marshal(msg.SignedBlock)
if err != nil {
return nil, nil, err
}
sig, err := ltPrv.EdSign(data)
if err != nil {
return nil, nil, err
}
copy(msg.Signature, sig.Bytes())
return prv, msg, nil
}
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