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package main
import (
"encoding/hex"
"flag"
"fmt"
"io"
"os"
"runtime"
"github.com/rfjakob/gocryptfs/v2/internal/configfile"
"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
"github.com/rfjakob/gocryptfs/v2/internal/cryptocore"
"github.com/rfjakob/gocryptfs/v2/internal/exitcodes"
"github.com/rfjakob/gocryptfs/v2/internal/fido2"
"github.com/rfjakob/gocryptfs/v2/internal/readpassword"
"github.com/rfjakob/gocryptfs/v2/internal/tlog"
)
// GitVersion is the gocryptfs version according to git, set by build.bash
var GitVersion = "[GitVersion not set - please compile using ./build.bash]"
// BuildDate is a date string like "2017-09-06", set by build.bash
var BuildDate = "0000-00-00"
const (
myName = "gocryptfs-xray"
)
// blockSize is the ciphertext block size including overheads
func blockSize(alg cryptocore.AEADTypeEnum) int {
return alg.NonceSize + contentenc.DefaultBS + cryptocore.AuthTagLen
}
func errExit(err error) {
fmt.Println(err)
os.Exit(1)
}
func prettyPrintHeader(h *contentenc.FileHeader, algo cryptocore.AEADTypeEnum) {
id := hex.EncodeToString(h.ID)
fmt.Printf("Header: Version: %d, Id: %s, assuming %s mode\n", h.Version, id, algo.Algo)
}
// printVersion prints a version string like this:
// gocryptfs v1.7-32-gcf99cfd; go-fuse v1.0.0-174-g22a9cb9; 2019-05-12 go1.12 linux/amd64
func printVersion() {
built := fmt.Sprintf("%s %s", BuildDate, runtime.Version())
fmt.Printf("%s %s; %s %s/%s\n",
myName, GitVersion, built,
runtime.GOOS, runtime.GOARCH)
}
func usage() {
printVersion()
fmt.Printf("\n")
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"+
" gocryptfs-xray -encrypt-paths myfs.sock\n")
}
// sum counts the number of true values
func sum(x ...*bool) (s int) {
for _, v := range x {
if *v {
s++
}
}
return s
}
type argContainer struct {
dumpmasterkey *bool
decryptPaths *bool
encryptPaths *bool
aessiv *bool
xchacha *bool
sep0 *bool
fido2 *string
version *bool
}
func main() {
var args argContainer
args.dumpmasterkey = flag.Bool("dumpmasterkey", false, "Decrypt and dump the master key")
args.decryptPaths = flag.Bool("decrypt-paths", false, "Decrypt file paths using gocryptfs control socket")
args.encryptPaths = flag.Bool("encrypt-paths", false, "Encrypt file paths using gocryptfs control socket")
args.sep0 = flag.Bool("0", false, "Use \\0 instead of \\n as separator")
args.aessiv = flag.Bool("aessiv", false, "Assume AES-SIV mode instead of AES-GCM")
args.xchacha = flag.Bool("xchacha", false, "Assume XChaCha20-Poly1305 mode instead of AES-GCM")
args.fido2 = flag.String("fido2", "", "Protect the masterkey using a FIDO2 token instead of a password")
args.version = flag.Bool("version", false, "Print version information")
flag.Usage = usage
flag.Parse()
if *args.version {
printVersion()
os.Exit(0)
}
s := sum(args.dumpmasterkey, args.decryptPaths, args.encryptPaths)
if s > 1 {
fmt.Fprintf(os.Stderr, "fatal: %d operations were requested\n", s)
os.Exit(1)
}
if flag.NArg() != 1 {
usage()
os.Exit(1)
}
fn := flag.Arg(0)
if *args.decryptPaths {
decryptPaths(fn, *args.sep0)
}
if *args.encryptPaths {
encryptPaths(fn, *args.sep0)
}
f, err := os.Open(fn)
if err != nil {
errExit(err)
}
defer f.Close()
if *args.dumpmasterkey {
dumpMasterKey(fn, *args.fido2)
} else {
inspectCiphertext(&args, f)
}
}
func dumpMasterKey(fn string, fido2Path string) {
tlog.Info.Enabled = false
cf, err := configfile.Load(fn)
if err != nil {
fmt.Fprintln(os.Stderr, err)
exitcodes.Exit(err)
}
var pw []byte
if cf.IsFeatureFlagSet(configfile.FlagFIDO2) {
if fido2Path == "" {
tlog.Fatal.Printf("Masterkey encrypted using FIDO2 token; need to use the --fido2 option.")
os.Exit(exitcodes.Usage)
}
pw = fido2.Secret(fido2Path, cf.FIDO2.CredentialID, cf.FIDO2.HMACSalt)
} else {
pw, err = readpassword.Once(nil, nil, "")
if err != nil {
tlog.Fatal.Println(err)
os.Exit(exitcodes.ReadPassword)
}
}
masterkey, err := cf.DecryptMasterKey(pw)
// Purge password from memory
for i := range pw {
pw[i] = 0
}
if err != nil {
tlog.Fatal.Println(err)
os.Exit(exitcodes.LoadConf)
}
fmt.Println(hex.EncodeToString(masterkey))
// Purge masterkey from memory
for i := range masterkey {
masterkey[i] = 0
}
}
func inspectCiphertext(args *argContainer, fd *os.File) {
algo := cryptocore.BackendGoGCM
if *args.aessiv {
algo = cryptocore.BackendAESSIV
} else if *args.xchacha {
algo = cryptocore.BackendXChaCha20Poly1305
}
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.Fprintf(os.Stderr, "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, algo)
var i int64
buf := make([]byte, blockSize(algo))
for i = 0; ; i++ {
off := contentenc.HeaderLen + i*int64(blockSize(algo))
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 < algo.NonceSize+cryptocore.AuthTagLen+1 {
errExit(fmt.Errorf("corrupt block: truncated data, len=%d", n))
}
data := buf[:n]
// Parse block data
iv := data[:algo.NonceSize]
tag := data[len(data)-cryptocore.AuthTagLen:]
if *args.aessiv {
tag = data[algo.NonceSize : algo.NonceSize+cryptocore.AuthTagLen]
}
fmt.Printf("Block %2d: IV: %s, Tag: %s, Offset: %5d Len: %d\n",
i, hex.EncodeToString(iv), hex.EncodeToString(tag), off, len(data))
}
}
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