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Diffstat (limited to 'internal/contentenc/file_header.go')
-rw-r--r--internal/contentenc/file_header.go60
1 files changed, 60 insertions, 0 deletions
diff --git a/internal/contentenc/file_header.go b/internal/contentenc/file_header.go
new file mode 100644
index 0000000..8a9dd2c
--- /dev/null
+++ b/internal/contentenc/file_header.go
@@ -0,0 +1,60 @@
+package contentenc
+
+// Per-file header
+//
+// Format: [ "Version" uint16 big endian ] [ "Id" 16 random bytes ]
+
+import (
+ "encoding/binary"
+ "fmt"
+
+ "github.com/rfjakob/gocryptfs/internal/cryptocore"
+)
+
+const (
+ // Current On-Disk-Format version
+ CurrentVersion = 2
+
+ HEADER_VERSION_LEN = 2 // uint16
+ HEADER_ID_LEN = 16 // 128 bit random file id
+ HEADER_LEN = HEADER_VERSION_LEN + HEADER_ID_LEN // Total header length
+)
+
+type FileHeader struct {
+ Version uint16
+ Id []byte
+}
+
+// Pack - serialize fileHeader object
+func (h *FileHeader) Pack() []byte {
+ if len(h.Id) != HEADER_ID_LEN || h.Version != CurrentVersion {
+ panic("FileHeader object not properly initialized")
+ }
+ buf := make([]byte, HEADER_LEN)
+ binary.BigEndian.PutUint16(buf[0:HEADER_VERSION_LEN], h.Version)
+ copy(buf[HEADER_VERSION_LEN:], h.Id)
+ return buf
+
+}
+
+// ParseHeader - parse "buf" into fileHeader object
+func ParseHeader(buf []byte) (*FileHeader, error) {
+ if len(buf) != HEADER_LEN {
+ return nil, fmt.Errorf("ParseHeader: invalid length: got %d, want %d", len(buf), HEADER_LEN)
+ }
+ var h FileHeader
+ h.Version = binary.BigEndian.Uint16(buf[0:HEADER_VERSION_LEN])
+ if h.Version != CurrentVersion {
+ return nil, fmt.Errorf("ParseHeader: invalid version: got %d, want %d", h.Version, CurrentVersion)
+ }
+ h.Id = buf[HEADER_VERSION_LEN:]
+ return &h, nil
+}
+
+// RandomHeader - create new fileHeader object with random Id
+func RandomHeader() *FileHeader {
+ var h FileHeader
+ h.Version = CurrentVersion
+ h.Id = cryptocore.RandBytes(HEADER_ID_LEN)
+ return &h
+}