package main import ( "encoding/hex" "flag" "fmt" "io" "os" "github.com/rfjakob/gocryptfs/internal/configfile" "github.com/rfjakob/gocryptfs/internal/contentenc" "github.com/rfjakob/gocryptfs/internal/cryptocore" "github.com/rfjakob/gocryptfs/internal/exitcodes" "github.com/rfjakob/gocryptfs/internal/readpassword" "github.com/rfjakob/gocryptfs/internal/tlog" ) const ( ivLen = contentenc.DefaultIVBits / 8 authTagLen = cryptocore.AuthTagLen blockSize = contentenc.DefaultBS + ivLen + cryptocore.AuthTagLen myName = "gocryptfs-xray" ) func errExit(err error) { fmt.Println(err) os.Exit(1) } func prettyPrintHeader(h *contentenc.FileHeader, aessiv bool) { id := hex.EncodeToString(h.ID) msg := "Header: Version: %d, Id: %s" if aessiv { msg += ", assuming AES-SIV mode" } else { msg += ", assuming AES-GCM mode" } fmt.Printf(msg+"\n", h.Version, id) } func usage() { fmt.Fprintf(os.Stderr, "Usage: %s [OPTIONS] FILE\n"+ "\n"+ "Options:\n", myName) flag.PrintDefaults() fmt.Fprintf(os.Stderr, "\n"+ "Examples:\n"+ " gocryptfs-xray myfs/mCXnISiv7nEmyc0glGuhTQ\n"+ " gocryptfs-xray -dumpmasterkey myfs/gocryptfs.conf\n") } func main() { dumpmasterkey := flag.Bool("dumpmasterkey", false, "Decrypt and dump the master key") aessiv := flag.Bool("aessiv", false, "Assume AES-SIV mode instead of AES-GCM") flag.Usage = usage flag.Parse() if flag.NArg() != 1 { usage() os.Exit(1) } fn := flag.Arg(0) fd, err := os.Open(fn) if err != nil { errExit(err) } defer fd.Close() if *dumpmasterkey { dumpMasterKey(fn) } else { inspectCiphertext(fd, *aessiv) } } func dumpMasterKey(fn string) { tlog.Info.Enabled = false pw := readpassword.Once(nil, "", "") masterkey, _, err := configfile.LoadAndDecrypt(fn, pw) if err != nil { fmt.Fprintln(os.Stderr, err) exitcodes.Exit(err) } fmt.Println(hex.EncodeToString(masterkey)) for i := range pw { pw[i] = 0 } } func inspectCiphertext(fd *os.File, aessiv bool) { headerBytes := make([]byte, contentenc.HeaderLen) n, err := fd.ReadAt(headerBytes, 0) if err == io.EOF && n == 0 { fmt.Println("empty file") os.Exit(0) } else if err == io.EOF { fmt.Printf("incomplete file header: read %d bytes, want %d\n", n, contentenc.HeaderLen) os.Exit(1) } else if err != nil { errExit(err) } header, err := contentenc.ParseHeader(headerBytes) if err != nil { errExit(err) } prettyPrintHeader(header, aessiv) var i int64 buf := make([]byte, blockSize) for i = 0; ; i++ { off := contentenc.HeaderLen + i*blockSize n, err := fd.ReadAt(buf, off) if err != nil && err != io.EOF { errExit(err) } if n == 0 && err == io.EOF { break } // A block contains at least the IV, the Auth Tag and 1 data byte if n < ivLen+authTagLen+1 { errExit(fmt.Errorf("corrupt block: truncated data, len=%d", n)) } data := buf[:n] // Parse block data iv := data[:ivLen] tag := data[len(data)-authTagLen:] if aessiv { tag = data[ivLen : ivLen+authTagLen] } fmt.Printf("Block %2d: IV: %s, Tag: %s, Offset: %5d Len: %d\n", i, hex.EncodeToString(iv), hex.EncodeToString(tag), off, len(data)) } }