Fixed a bug that disabled RSA when copying from a non RSA-encrypted s…

…torage.

When copying to an RSA-encrypted storage, we relied on the RSA encryption
version to determine if a chunk is a snapshot chunk or a file chunk.  This is
wrong when the source storage is not encrypted or not RSA-encrypted.  There
is a more reliable to determine if a chunk is a snapshot chunk or not.

src/duplicacy_backupmanager.go

@@ -1626,6 +1626,9 @@ func (manager *BackupManager) CopySnapshots(otherManager *BackupManager, snapsho
 		return true
 	}
 
+	// These two maps store hashes of chunks in the source and destination storages, respectively.  Note that
+	// the value of 'chunks' is used to indicated if the chunk is a snapshot chunk, while the value of 'otherChunks' 
+	// is not used.
 	chunks := make(map[string]bool)
 	otherChunks := make(map[string]bool)
 
@@ -1638,21 +1641,15 @@ func (manager *BackupManager) CopySnapshots(otherManager *BackupManager, snapsho
 		LOG_TRACE("SNAPSHOT_COPY", "Copying snapshot %s at revision %d", snapshot.ID, snapshot.Revision)
 
 		for _, chunkHash := range snapshot.FileSequence {
-			if _, found := chunks[chunkHash]; !found {
-				chunks[chunkHash] = true
-			}
+			chunks[chunkHash] = true  // The chunk is a snapshot chunk
 		}
 
 		for _, chunkHash := range snapshot.ChunkSequence {
-			if _, found := chunks[chunkHash]; !found {
-				chunks[chunkHash] = true
-			}
+			chunks[chunkHash] = true  // The chunk is a snapshot chunk
 		}
 
 		for _, chunkHash := range snapshot.LengthSequence {
-			if _, found := chunks[chunkHash]; !found {
-				chunks[chunkHash] = true
-			}
+			chunks[chunkHash] = true  // The chunk is a snapshot chunk
 		}
 
 		description := manager.SnapshotManager.DownloadSequence(snapshot.ChunkSequence)
@@ -1665,7 +1662,7 @@ func (manager *BackupManager) CopySnapshots(otherManager *BackupManager, snapsho
 
 		for _, chunkHash := range snapshot.ChunkHashes {
 			if _, found := chunks[chunkHash]; !found {
-				chunks[chunkHash] = true
+				chunks[chunkHash] = false  // The chunk is a file chunk
 			}
 		}
 
@@ -1721,7 +1718,7 @@ func (manager *BackupManager) CopySnapshots(otherManager *BackupManager, snapsho
 	totalSkipped := 0
 	chunkIndex := 0
 
-	for chunkHash := range chunks {
+	for chunkHash, isSnapshot := range chunks {
 		chunkIndex++
 		chunkID := manager.config.GetChunkIDFromHash(chunkHash)
 		newChunkID := otherManager.config.GetChunkIDFromHash(chunkHash)
@@ -1732,11 +1729,7 @@ func (manager *BackupManager) CopySnapshots(otherManager *BackupManager, snapsho
 			newChunk := otherManager.config.GetChunk()
 			newChunk.Reset(true)
 			newChunk.Write(chunk.GetBytes())
-			if chunk.encryptionVersion == ENCRYPTION_VERSION_RSA {
-				newChunk.encryptionVersion = CHUNK_RSA_ENCRYPTION_ENABLED
-			} else {
-				newChunk.encryptionVersion = CHUNK_RSA_ENCRYPTION_DISABLED
-			}
+			newChunk.isSnapshot = isSnapshot
 			chunkUploader.StartChunk(newChunk, chunkIndex)
 			totalCopied++
 		} else {

src/duplicacy_chunk.go

@@ -63,8 +63,8 @@ type Chunk struct {
 	config *Config // Every chunk is associated with a Config object.  Which hashing algorithm to use is determined
 	// by the config
 
-	encryptionVersion byte // The version type in the encrytion header; for a chunk to be copied, this field contains
-	// one of the CHUNK_RSA_ENCRYPTION_* constants to indicate how the new chunk should be encrypted
+	isSnapshot bool // Indicates if the chunk is a snapshot chunk (instead of a file chunk).  This is only used by RSA
+	                // encryption, where a snapshot chunk is not encrypted by RSA
 }
 
 // Magic word to identify a duplicacy format encrypted file, plus a version number.
@@ -73,11 +73,6 @@ var ENCRYPTION_HEADER = "duplicacy\000"
 // RSA encrypted chunks start with "duplicacy\002"
 var ENCRYPTION_VERSION_RSA byte = 2
 
-// These constants are used to control how a new chunk should be encrypted by the copy command
-var CHUNK_RSA_ENCRYPTION_DEFAULT byte = 0   // No RSA encryption explicitly requested
-var CHUNK_RSA_ENCRYPTION_DISABLED byte = 1  // The RSA encryption should be turned off
-var CHUNK_RSA_ENCRYPTION_ENABLED byte = 2   // The RSA encryption should be forced on
-
 // CreateChunk creates a new chunk.
 func CreateChunk(config *Config, bufferNeeded bool) *Chunk {
 
@@ -126,6 +121,7 @@ func (chunk *Chunk) Reset(hashNeeded bool) {
 	chunk.hash = nil
 	chunk.id = ""
 	chunk.size = 0
+	chunk.isSnapshot = false
 }
 
 // Write implements the Writer interface.
@@ -200,11 +196,8 @@ func (chunk *Chunk) Encrypt(encryptionKey []byte, derivationKey string, isSnapsh
 
 		key := encryptionKey
 		usingRSA := false
-		// If encryptionVersion is not set, use the default setting (RSA for file chunks only);
-		// otherwise, enable RSA encryption only when explicitly requested
-		if chunk.config.rsaPublicKey != nil &&
-		    ((!isSnapshot && chunk.encryptionVersion == CHUNK_RSA_ENCRYPTION_DEFAULT) || chunk.encryptionVersion == CHUNK_RSA_ENCRYPTION_ENABLED) {
-			// If the chunk is not a snpashot chunk, we attempt to encrypt it with the RSA publick key if there is one
+		// Enable RSA encryption only when the chunk is not a snapshot chunk
+		if chunk.config.rsaPublicKey != nil && !isSnapshot && !chunk.isSnapshot {
 			randomKey := make([]byte, 32)
 			_, err := rand.Read(randomKey)
 			if err != nil {
@@ -331,8 +324,6 @@ func (chunk *Chunk) Decrypt(encryptionKey []byte, derivationKey string) (err err
 	chunk.buffer, encryptedBuffer = encryptedBuffer, chunk.buffer
 	headerLength := len(ENCRYPTION_HEADER)
 
-	chunk.encryptionVersion = 0
-
 	if len(encryptionKey) > 0 {
 
 		key := encryptionKey
@@ -357,12 +348,12 @@ func (chunk *Chunk) Decrypt(encryptionKey []byte, derivationKey string) (err err
 			return fmt.Errorf("The storage doesn't seem to be encrypted")
 		}
 
-		chunk.encryptionVersion = encryptedBuffer.Bytes()[headerLength-1]
-		if chunk.encryptionVersion != 0 && chunk.encryptionVersion != ENCRYPTION_VERSION_RSA {
-			return fmt.Errorf("Unsupported encryption version %d", chunk.encryptionVersion)
+		encryptionVersion := encryptedBuffer.Bytes()[headerLength-1]
+		if encryptionVersion != 0 && encryptionVersion != ENCRYPTION_VERSION_RSA {
+			return fmt.Errorf("Unsupported encryption version %d", encryptionVersion)
 		}
 
-		if chunk.encryptionVersion == ENCRYPTION_VERSION_RSA {
+		if encryptionVersion == ENCRYPTION_VERSION_RSA {
 			if chunk.config.rsaPrivateKey == nil {
 				LOG_ERROR("CHUNK_DECRYPT", "An RSA private key is required to decrypt the chunk")
 				return fmt.Errorf("An RSA private key is required to decrypt the chunk")