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// -*- Mode: Go; indent-tabs-mode: t -*-
//go:build !nosecboot
/*
* Copyright (C) 2024 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package keys
import (
"crypto/rand"
"io"
"os"
"path/filepath"
sb "github.com/snapcore/secboot"
sb_plainkey "github.com/snapcore/secboot/plainkey"
"github.com/snapcore/snapd/osutil"
)
const (
protectorKeySize = 32
)
var (
sbNewProtectedKey = sb_plainkey.NewProtectedKey
)
// ProtectorKey is a key that can be used to protect "plainkey" keys.
type ProtectorKey []byte
// NewProtectorKey creates a new random ProtectorKey.
func NewProtectorKey() (ProtectorKey, error) {
key := make(ProtectorKey, protectorKeySize)
_, err := rand.Read(key[:])
return key, err
}
// SaveToFile saves the ProtectorKey to a file at given path.
func (key ProtectorKey) SaveToFile(path string) error {
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
return err
}
return osutil.AtomicWriteFile(path, key[:], 0600, 0)
}
// PlainKey is a wrapper for a secboot KeyData representing a plainkey.
type PlainKey struct {
keyData *sb.KeyData
}
// CreateProtectedKey creates a protected key for a given ProtectorKey
// and primary key. It returns a the protected key wrapped as a PlainKey
// as well the used primary key and the unlock key.
// If primaryKey is nil, the primary key will be generated.
func (key ProtectorKey) CreateProtectedKey(primaryKey []byte) (*PlainKey, []byte, []byte, error) {
protectedKey, generatedPK, unlockKey, err := sbNewProtectedKey(rand.Reader, key[:], primaryKey)
return &PlainKey{protectedKey}, generatedPK, unlockKey, err
}
// KeyDataWriter is a the same as KeyDataWriter from
// github.com/canonical/secboot.
type KeyDataWriter interface {
io.Writer
Commit() error
}
// Write writes a PlainKey to a KeyDataWriter.
func (key *PlainKey) Write(writer KeyDataWriter) error {
return key.keyData.WriteAtomic(writer)
}
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