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/readpassword" ) const ( ivLen = contentenc.DefaultIVBits / 8 blockSize = contentenc.DefaultBS + ivLen + cryptocore.AuthTagLen myName = "gocryptfs-xray" ) func errExit(err error) { fmt.Println(err) os.Exit(1) } func prettyPrintHeader(h *contentenc.FileHeader) { id := hex.EncodeToString(h.ID) fmt.Printf("Header: Version: %d, Id: %s\n", h.Version, id) } func main() { dumpmasterkey := flag.Bool("dumpmasterkey", false, "Decrypt and dump the master key") flag.Parse() if flag.NArg() != 1 { 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") 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) } } func dumpMasterKey(fn string) { pw := readpassword.Once("") masterkey, _, err := configfile.LoadConfFile(fn, pw) if err != nil { fmt.Fprintln(os.Stderr, err) } fmt.Println(hex.EncodeToString(masterkey)) } func inspectCiphertext(fd *os.File) { 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) var i int64 for i = 0; ; i++ { blockLen := int64(blockSize) off := contentenc.HeaderLen + i*blockSize iv := make([]byte, ivLen) _, err := fd.ReadAt(iv, off) if err == io.EOF { break } else if err != nil { errExit(err) } tag := make([]byte, cryptocore.AuthTagLen) _, err = fd.ReadAt(tag, off+blockSize-cryptocore.AuthTagLen) if err == io.EOF { fi, err2 := fd.Stat() if err2 != nil { errExit(err2) } _, err2 = fd.ReadAt(tag, fi.Size()-cryptocore.AuthTagLen) if err2 != nil { errExit(err2) } blockLen = (fi.Size() - contentenc.HeaderLen) % blockSize } else if err != nil { errExit(err) } fmt.Printf("Block %2d: IV: %s, Tag: %s, Offset: %5d Len: %d\n", i, hex.EncodeToString(iv), hex.EncodeToString(tag), off, blockLen) } }