FEATURE (encryption): Add backups encryption

Author: RostislavDugin

README.md

@@ -40,13 +40,13 @@
 - **Precise timing**: run backups at specific times (e.g., 4 AM during low traffic)
 - **Smart compression**: 4-8x space savings with balanced compression (~20% overhead)
 
-### 🗄️ **Multiple Storage Destinations** <a href="https://postgresus.com/storages">(docs)</a>
+### 🗄️ **Multiple Storage Destinations** <a href="https://postgresus.com/storages">(view supported)</a>
 
 - **Local storage**: Keep backups on your VPS/server
 - **Cloud storage**: S3, Cloudflare R2, Google Drive, NAS, Dropbox and more
 - **Secure**: All data stays under your control
 
-### 📱 **Smart Notifications** <a href="https://postgresus.com/notifiers">(docs)</a>
+### 📱 **Smart Notifications** <a href="https://postgresus.com/notifiers">(view supported)</a>
 
 - **Multiple channels**: Email, Telegram, Slack, Discord, webhooks
 - **Real-time updates**: Success and failure notifications
@@ -58,6 +58,13 @@
 - **SSL support**: Secure connections available
 - **Easy restoration**: One-click restore from any backup
 
+### 🔒 **Backup Encryption** <a href="https://postgresus.com/encryption">(docs)</a>
+
+- **AES-256-GCM encryption**: Enterprise-grade protection for backup files
+- **Zero-trust storage**: Encrypted backups are useless so you can keep in shared storages like S3, Azure Blob Storage, etc.
+- **Optionality**: Encrypted backups are optional and can be enabled or disabled if you wish
+- **Download unencrypted**: You can still download unencrypted backups via the 'Download' button to use them in `pg_restore` or other tools.
+
 ### 👥 **Suitable for Teams** <a href="https://postgresus.com/access-management">(docs)</a>
 
 - **Workspaces**: Group databases, notifiers and storages for different projects or teams

backend/internal/features/backups/backups/controller_test.go

@@ -524,7 +524,7 @@ func Test_CancelBackup_InProgressBackup_SuccessfullyCancelled(t *testing.T) {
 	assert.NoError(t, err)
 
 	// Register a cancellable context for the backup
-	GetBackupService().backupContextMgr.RegisterBackup(backup.ID, func() {})
+	GetBackupService().backupContextManager.RegisterBackup(backup.ID, func() {})
 
 	resp := test_utils.MakePostRequest(
 		t,

backend/internal/features/backups/backups/di.go

@@ -7,6 +7,7 @@ import (
 	"postgresus-backend/internal/features/databases"
 	"postgresus-backend/internal/features/notifiers"
 	"postgresus-backend/internal/features/storages"
+	users_repositories "postgresus-backend/internal/features/users/repositories"
 	workspaces_services "postgresus-backend/internal/features/workspaces/services"
 	"postgresus-backend/internal/util/logger"
 	"time"
@@ -23,6 +24,7 @@ var backupService = &BackupService{
 	notifiers.GetNotifierService(),
 	notifiers.GetNotifierService(),
 	backups_config.GetBackupConfigService(),
+	users_repositories.GetSecretKeyRepository(),
 	usecases.GetCreateBackupUsecase(),
 	logger.GetLogger(),
 	[]BackupRemoveListener{},

backend/internal/features/backups/backups/dto.go

@@ -1,5 +1,10 @@
 package backups
 
+import (
+	"io"
+	"postgresus-backend/internal/features/backups/backups/encryption"
+)
+
 type GetBackupsRequest struct {
 	DatabaseID string `form:"database_id" binding:"required"`
 	Limit      int    `form:"limit"`
@@ -12,3 +17,12 @@ type GetBackupsResponse struct {
 	Limit   int       `json:"limit"`
 	Offset  int       `json:"offset"`
 }
+
+type decryptionReaderCloser struct {
+	*encryption.DecryptionReader
+	baseReader io.ReadCloser
+}
+
+func (r *decryptionReaderCloser) Close() error {
+	return r.baseReader.Close()
+}

backend/internal/features/backups/backups/encryption/decrypting_reader.go

@@ -0,0 +1,156 @@
+package encryption
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+	"fmt"
+	"io"
+
+	"github.com/google/uuid"
+)
+
+type DecryptionReader struct {
+	baseReader io.Reader
+	cipher     cipher.AEAD
+	buffer     []byte
+	nonce      []byte
+	chunkIndex uint64
+	headerRead bool
+	eof        bool
+}
+
+func NewDecryptionReader(
+	baseReader io.Reader,
+	masterKey string,
+	backupID uuid.UUID,
+	salt []byte,
+	nonce []byte,
+) (*DecryptionReader, error) {
+	if len(salt) != SaltLen {
+		return nil, fmt.Errorf("salt must be %d bytes, got %d", SaltLen, len(salt))
+	}
+	if len(nonce) != NonceLen {
+		return nil, fmt.Errorf("nonce must be %d bytes, got %d", NonceLen, len(nonce))
+	}
+
+	derivedKey, err := DeriveBackupKey(masterKey, backupID, salt)
+	if err != nil {
+		return nil, fmt.Errorf("failed to derive backup key: %w", err)
+	}
+
+	block, err := aes.NewCipher(derivedKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	reader := &DecryptionReader{
+		baseReader,
+		aesgcm,
+		make([]byte, 0),
+		nonce,
+		0,
+		false,
+		false,
+	}
+
+	if err := reader.readAndValidateHeader(salt, nonce); err != nil {
+		return nil, err
+	}
+
+	return reader, nil
+}
+
+func (r *DecryptionReader) Read(p []byte) (n int, err error) {
+	for len(r.buffer) < len(p) && !r.eof {
+		if err := r.readAndDecryptChunk(); err != nil {
+			if err == io.EOF {
+				r.eof = true
+				break
+			}
+			return 0, err
+		}
+	}
+
+	if len(r.buffer) == 0 {
+		return 0, io.EOF
+	}
+
+	n = copy(p, r.buffer)
+	r.buffer = r.buffer[n:]
+
+	return n, nil
+}
+
+func (r *DecryptionReader) readAndValidateHeader(expectedSalt, expectedNonce []byte) error {
+	header := make([]byte, HeaderLen)
+
+	if _, err := io.ReadFull(r.baseReader, header); err != nil {
+		return fmt.Errorf("failed to read header: %w", err)
+	}
+
+	magic := string(header[0:MagicBytesLen])
+	if magic != MagicBytes {
+		return fmt.Errorf("invalid magic bytes: expected %s, got %s", MagicBytes, magic)
+	}
+
+	salt := header[MagicBytesLen : MagicBytesLen+SaltLen]
+	nonce := header[MagicBytesLen+SaltLen : MagicBytesLen+SaltLen+NonceLen]
+
+	if string(salt) != string(expectedSalt) {
+		return fmt.Errorf("salt mismatch in file header")
+	}
+
+	if string(nonce) != string(expectedNonce) {
+		return fmt.Errorf("nonce mismatch in file header")
+	}
+
+	r.headerRead = true
+	return nil
+}
+
+func (r *DecryptionReader) readAndDecryptChunk() error {
+	lengthBuf := make([]byte, 4)
+	if _, err := io.ReadFull(r.baseReader, lengthBuf); err != nil {
+		return err
+	}
+
+	chunkLen := binary.BigEndian.Uint32(lengthBuf)
+	if chunkLen == 0 || chunkLen > ChunkSize+16 {
+		return fmt.Errorf("invalid chunk length: %d", chunkLen)
+	}
+
+	encrypted := make([]byte, chunkLen)
+	if _, err := io.ReadFull(r.baseReader, encrypted); err != nil {
+		return fmt.Errorf("failed to read encrypted chunk: %w", err)
+	}
+
+	chunkNonce := r.generateChunkNonce()
+
+	decrypted, err := r.cipher.Open(nil, chunkNonce, encrypted, nil)
+	if err != nil {
+		return fmt.Errorf(
+			"failed to decrypt chunk (authentication failed - file may be corrupted or tampered): %w",
+			err,
+		)
+	}
+
+	r.buffer = append(r.buffer, decrypted...)
+	r.chunkIndex++
+
+	return nil
+}
+
+func (r *DecryptionReader) generateChunkNonce() []byte {
+	chunkNonce := make([]byte, NonceLen)
+	copy(chunkNonce, r.nonce)
+
+	binary.BigEndian.PutUint64(chunkNonce[4:], r.chunkIndex)
+
+	return chunkNonce
+}

backend/internal/features/backups/backups/encryption/encrypting_writer.go

@@ -0,0 +1,147 @@
+package encryption
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+	"fmt"
+	"io"
+
+	"github.com/google/uuid"
+)
+
+type EncryptionWriter struct {
+	baseWriter    io.Writer
+	cipher        cipher.AEAD
+	buffer        []byte
+	nonce         []byte
+	salt          []byte
+	chunkIndex    uint64
+	headerWritten bool
+}
+
+func NewEncryptionWriter(
+	baseWriter io.Writer,
+	masterKey string,
+	backupID uuid.UUID,
+	salt []byte,
+	nonce []byte,
+) (*EncryptionWriter, error) {
+	if len(salt) != SaltLen {
+		return nil, fmt.Errorf("salt must be %d bytes, got %d", SaltLen, len(salt))
+	}
+	if len(nonce) != NonceLen {
+		return nil, fmt.Errorf("nonce must be %d bytes, got %d", NonceLen, len(nonce))
+	}
+
+	derivedKey, err := DeriveBackupKey(masterKey, backupID, salt)
+	if err != nil {
+		return nil, fmt.Errorf("failed to derive backup key: %w", err)
+	}
+
+	block, err := aes.NewCipher(derivedKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	writer := &EncryptionWriter{
+		baseWriter:    baseWriter,
+		cipher:        aesgcm,
+		buffer:        make([]byte, 0, ChunkSize),
+		nonce:         nonce,
+		chunkIndex:    0,
+		headerWritten: false,
+		salt:          salt, // Store salt for lazy header writing
+	}
+
+	return writer, nil
+}
+
+func (w *EncryptionWriter) Write(p []byte) (n int, err error) {
+	// Write header on first write (lazy initialization)
+	if !w.headerWritten {
+		if err := w.writeHeader(w.salt, w.nonce); err != nil {
+			return 0, fmt.Errorf("failed to write header: %w", err)
+		}
+	}
+
+	n = len(p)
+	w.buffer = append(w.buffer, p...)
+
+	for len(w.buffer) >= ChunkSize {
+		chunk := w.buffer[:ChunkSize]
+		if err := w.encryptAndWriteChunk(chunk); err != nil {
+			return 0, err
+		}
+		w.buffer = w.buffer[ChunkSize:]
+	}
+
+	return n, nil
+}
+
+func (w *EncryptionWriter) Close() error {
+	// Write header if it hasn't been written yet (in case Close is called without any writes)
+	if !w.headerWritten {
+		if err := w.writeHeader(w.salt, w.nonce); err != nil {
+			return fmt.Errorf("failed to write header: %w", err)
+		}
+	}
+
+	if len(w.buffer) > 0 {
+		if err := w.encryptAndWriteChunk(w.buffer); err != nil {
+			return err
+		}
+		w.buffer = nil
+	}
+	return nil
+}
+
+func (w *EncryptionWriter) writeHeader(salt, nonce []byte) error {
+	header := make([]byte, HeaderLen)
+
+	copy(header[0:MagicBytesLen], []byte(MagicBytes))
+	copy(header[MagicBytesLen:MagicBytesLen+SaltLen], salt)
+	copy(header[MagicBytesLen+SaltLen:MagicBytesLen+SaltLen+NonceLen], nonce)
+
+	_, err := w.baseWriter.Write(header)
+	if err != nil {
+		return fmt.Errorf("failed to write header: %w", err)
+	}
+
+	w.headerWritten = true
+	return nil
+}
+
+func (w *EncryptionWriter) encryptAndWriteChunk(chunk []byte) error {
+	chunkNonce := w.generateChunkNonce()
+
+	encrypted := w.cipher.Seal(nil, chunkNonce, chunk, nil)
+
+	lengthBuf := make([]byte, 4)
+	binary.BigEndian.PutUint32(lengthBuf, uint32(len(encrypted)))
+
+	if _, err := w.baseWriter.Write(lengthBuf); err != nil {
+		return fmt.Errorf("failed to write chunk length: %w", err)
+	}
+
+	if _, err := w.baseWriter.Write(encrypted); err != nil {
+		return fmt.Errorf("failed to write encrypted chunk: %w", err)
+	}
+
+	w.chunkIndex++
+	return nil
+}
+
+func (w *EncryptionWriter) generateChunkNonce() []byte {
+	chunkNonce := make([]byte, NonceLen)
+	copy(chunkNonce, w.nonce)
+
+	binary.BigEndian.PutUint64(chunkNonce[4:], w.chunkIndex)
+
+	return chunkNonce
+}