sysops
144cb2982d
New POST /backup/download (admin-only) tars the whole jsondb directory (all servers/clients/users/settings) and streams it back as a file download. If a passphrase is given, the archive is encrypted first (AES-256-GCM, scrypt-derived key, backup/encrypt.go) - a small self-contained format, not gpg/OpenPGP-compatible, to avoid shelling out to an external binary or adding a PGP dependency. Deliberately does NOT upload anywhere automatically (e.g. to Nextcloud) - the archive only ever leaves the server as this one HTTP response to the requesting admin, who is responsible for storing it themselves. New "Download Backup" button + passphrase modal on the Global Settings page.
86 lines
2.3 KiB
Go
86 lines
2.3 KiB
Go
package backup
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"errors"
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"io"
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"golang.org/x/crypto/scrypt"
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)
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const (
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saltSize = 16
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keySize = 32 // AES-256
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)
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// deriveKey turns a passphrase into a 32-byte AES key via scrypt, using the
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// given salt. scrypt (N=32768, r=8, p=1) is deliberately expensive to slow
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// down offline brute-force of a leaked archive.
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func deriveKey(passphrase string, salt []byte) ([]byte, error) {
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return scrypt.Key([]byte(passphrase), salt, 32768, 8, 1, keySize)
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}
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// Encrypt symmetrically encrypts data with a passphrase using scrypt key
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// derivation + AES-256-GCM. Output layout: [16-byte salt][12-byte
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// nonce][GCM ciphertext+tag]. This is a small self-contained format
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// specific to this app - NOT OpenPGP/gpg-compatible - chosen to avoid
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// shelling out to an external gpg binary or adding a full PGP dependency.
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func Encrypt(plaintext []byte, passphrase string) ([]byte, error) {
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salt := make([]byte, saltSize)
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if _, err := io.ReadFull(rand.Reader, salt); err != nil {
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return nil, err
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}
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key, err := deriveKey(passphrase, salt)
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if err != nil {
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return nil, err
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}
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, gcm.NonceSize())
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if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
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return nil, err
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}
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ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
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out := make([]byte, 0, saltSize+len(nonce)+len(ciphertext))
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out = append(out, salt...)
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out = append(out, nonce...)
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out = append(out, ciphertext...)
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return out, nil
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}
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// Decrypt reverses Encrypt, for manual restore/recovery.
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func Decrypt(data []byte, passphrase string) ([]byte, error) {
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if len(data) < saltSize {
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return nil, errors.New("backup: ciphertext too short")
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}
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salt := data[:saltSize]
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key, err := deriveKey(passphrase, salt)
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if err != nil {
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return nil, err
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}
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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nonceSize := gcm.NonceSize()
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if len(data) < saltSize+nonceSize {
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return nil, errors.New("backup: ciphertext too short")
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}
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nonce := data[saltSize : saltSize+nonceSize]
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ciphertext := data[saltSize+nonceSize:]
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return gcm.Open(nil, nonce, ciphertext, nil)
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}
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