hardcoresushi/libgocryptfs
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xray: add xchacha support

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Also use the new cryptocore algo names.
This commit is contained in:
Jakob Unterwurzacher 2021-08-23 22:19:30 +02:00
parent 20ca63cdbc
commit abaa12992c
3 changed files with 41 additions and 35 deletions
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72
gocryptfs-xray/xray_main.go
View File

@ -24,26 +24,22 @@ var GitVersion = "[GitVersion not set - please compile using ./build.bash]"
var BuildDate = "0000-00-00"
const (
ivLen = contentenc.DefaultIVBits / 8
authTagLen = cryptocore.AuthTagLen
blockSize = contentenc.DefaultBS + ivLen + cryptocore.AuthTagLen
myName = "gocryptfs-xray"
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, aessiv bool) {
func prettyPrintHeader(h *contentenc.FileHeader, algo cryptocore.AEADTypeEnum) {
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)
fmt.Printf("Header: Version: %d, Id: %s, assuming %s mode\n", h.Version, id, algo.Name)
}
// printVersion prints a version string like this:
@ -79,21 +75,25 @@ func sum(x ...*bool) (s int) {
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 struct {
dumpmasterkey *bool
decryptPaths *bool
encryptPaths *bool
aessiv *bool
sep0 *bool
fido2 *string
version *bool
}
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")
@ -121,15 +121,15 @@ func main() {
if *args.encryptPaths {
encryptPaths(fn, *args.sep0)
}
fd, err := os.Open(fn)
f, err := os.Open(fn)
if err != nil {
errExit(err)
}
defer fd.Close()
defer f.Close()
if *args.dumpmasterkey {
dumpMasterKey(fn, *args.fido2)
} else {
inspectCiphertext(fd, *args.aessiv)
inspectCiphertext(&args, f)
}
}
@ -166,7 +166,13 @@ func dumpMasterKey(fn string, fido2Path string) {
}
}
func inspectCiphertext(fd *os.File, aessiv bool) {
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 {
@ -182,11 +188,11 @@ func inspectCiphertext(fd *os.File, aessiv bool) {
if err != nil {
errExit(err)
}
prettyPrintHeader(header, aessiv)
prettyPrintHeader(header, algo)
var i int64
buf := make([]byte, blockSize)
buf := make([]byte, blockSize(algo))
for i = 0; ; i++ {
off := contentenc.HeaderLen + i*blockSize
off := contentenc.HeaderLen + i*int64(blockSize(algo))
n, err := fd.ReadAt(buf, off)
if err != nil && err != io.EOF {
errExit(err)
@ -195,15 +201,15 @@ func inspectCiphertext(fd *os.File, aessiv bool) {
break
}
// A block contains at least the IV, the Auth Tag and 1 data byte
if n < ivLen+authTagLen+1 {
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[:ivLen]
tag := data[len(data)-authTagLen:]
if aessiv {
tag = data[ivLen : ivLen+authTagLen]
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))

2
gocryptfs-xray/xray_tests/aesgcm_fs.xray.txt
View File

@ -1,3 +1,3 @@
Header: Version: 2, Id: 8932adf303fe0289679d47fa84d2b241, assuming AES-GCM mode
Header: Version: 2, Id: 8932adf303fe0289679d47fa84d2b241, assuming AES-GCM-256-Go mode
Block 0: IV: c8536b4bfd92f5dc3c1e2ac29f116d4a, Tag: 22b20422749b2f4bba67ec7d3bb1ac34, Offset: 18 Len: 4128
Block 1: IV: 2de68f4965779bb137ef2b3c20453556, Tag: 3e8758d6872234b1fffab2504e623467, Offset: 4146 Len: 936

2
gocryptfs-xray/xray_tests/aessiv_fs.xray.txt
View File

@ -1,3 +1,3 @@
Header: Version: 2, Id: d839806747918e345633fcdd0988e67c, assuming AES-SIV mode
Header: Version: 2, Id: d839806747918e345633fcdd0988e67c, assuming AES-SIV-512-Go mode
Block 0: IV: 1d3ce2b13260f83766ccf9a670478a4b, Tag: 0b6f95bd523b4c93704e15ecc6bef8e7, Offset: 18 Len: 4128
Block 1: IV: 7eb947d2adf18adf3bed39bbc8052968, Tag: 1a272903e5a987f53f07344840387c20, Offset: 4146 Len: 936