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libgocryptfs: update to gocryptfs v2.2.0

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This commit is contained in:
Matéo Duparc 2021-10-12 16:54:56 +02:00
commit bd5d53f50e
Signed by: hardcoresushi
GPG Key ID: 007F84120107191E
22 changed files with 795 additions and 299 deletions
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6
internal/configfile/config_file.go
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@ -301,7 +301,7 @@ func (cf *ConfFile) WriteFile() error {
err = fd.Sync()
if err != nil {
// This can happen on network drives: FRITZ.NAS mounted on MacOS returns
// "operation not supported": https://github.com/rfjakob/gocryptfs/v2/issues/390
// "operation not supported": https://github.com/rfjakob/gocryptfs/issues/390
// Try sync instead
syscall.Sync()
}
@ -322,8 +322,8 @@ func getKeyEncrypter(scryptHash []byte, useHKDF bool) *contentenc.ContentEnc {
if useHKDF {
IVLen = contentenc.DefaultIVBits
}
cc := cryptocore.New(scryptHash, cryptocore.BackendGoGCM, IVLen, useHKDF, false)
ce := contentenc.New(cc, 4096, false)
cc := cryptocore.New(scryptHash, cryptocore.BackendGoGCM, IVLen, useHKDF)
ce := contentenc.New(cc, 4096)
return ce
}

13
internal/contentenc/content.go
View File

@ -10,7 +10,6 @@ import (
"sync"
"../cryptocore"
"../stupidgcm"
)
const (
@ -40,8 +39,6 @@ type ContentEnc struct {
allZeroBlock []byte
// All-zero block of size IVBitLen/8, for fast compares
allZeroNonce []byte
// Force decode even if integrity check fails (openSSL only)
forceDecode bool
// Ciphertext block "sync.Pool" pool. Always returns cipherBS-sized byte
// slices (usually 4128 bytes).
@ -59,7 +56,7 @@ type ContentEnc struct {
}
// New returns an initialized ContentEnc instance.
func New(cc *cryptocore.CryptoCore, plainBS uint64, forceDecode bool) *ContentEnc {
func New(cc *cryptocore.CryptoCore, plainBS uint64) *ContentEnc {
if MAX_KERNEL_WRITE%plainBS != 0 {
log.Panicf("unaligned MAX_KERNEL_WRITE=%d", MAX_KERNEL_WRITE)
}
@ -77,7 +74,6 @@ func New(cc *cryptocore.CryptoCore, plainBS uint64, forceDecode bool) *ContentEn
cipherBS: cipherBS,
allZeroBlock: make([]byte, cipherBS),
allZeroNonce: make([]byte, cc.IVLen),
forceDecode: forceDecode,
cBlockPool: newBPool(int(cipherBS)),
CReqPool: newBPool(cReqSize),
pBlockPool: newBPool(int(plainBS)),
@ -107,10 +103,8 @@ func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, file
var pBlock []byte
pBlock, err = be.DecryptBlock(cBlock, blockNo, fileID)
if err != nil {
if !(be.forceDecode && err == stupidgcm.ErrAuth) {
break
}
}
pBuf.Write(pBlock)
be.pBlockPool.Put(pBlock)
blockNo++
@ -159,7 +153,7 @@ func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileID []b
nonce := ciphertext[:be.cryptoCore.IVLen]
if bytes.Equal(nonce, be.allZeroNonce) {
// Bug in tmpfs?
// https://github.com/rfjakob/gocryptfs/v2/issues/56
// https://github.com/rfjakob/gocryptfs/issues/56
// http://www.spinics.net/lists/kernel/msg2370127.html
return nil, errors.New("all-zero nonce")
}
@ -172,9 +166,6 @@ func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileID []b
plaintext, err := be.cryptoCore.AEADCipher.Open(plaintext, nonce, ciphertext, aData)
if err != nil {
if be.forceDecode && err == stupidgcm.ErrAuth {
return plaintext, err
}
return nil, err
}

21
internal/cryptocore/cryptocore.go
View File

@ -31,11 +31,11 @@ type AEADTypeEnum struct {
NonceSize int
}
// BackendOpenSSL specifies the OpenSSL backend.
// BackendOpenSSL specifies the OpenSSL AES-256-GCM backend.
// "AES-GCM-256-OpenSSL" in gocryptfs -speed.
var BackendOpenSSL AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-OpenSSL", 16}
// BackendGoGCM specifies the Go based GCM backend.
// BackendGoGCM specifies the Go based AES-256-GCM backend.
// "AES-GCM-256-Go" in gocryptfs -speed.
var BackendGoGCM AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-Go", 16}
@ -47,6 +47,9 @@ var BackendAESSIV AEADTypeEnum = AEADTypeEnum{"AES-SIV-512-Go", siv_aead.NonceSi
// "XChaCha20-Poly1305-Go" in gocryptfs -speed.
var BackendXChaCha20Poly1305 AEADTypeEnum = AEADTypeEnum{"XChaCha20-Poly1305-Go", chacha20poly1305.NonceSizeX}
// BackendXChaCha20Poly1305OpenSSL specifies XChaCha20-Poly1305-OpenSSL.
var BackendXChaCha20Poly1305OpenSSL AEADTypeEnum = AEADTypeEnum{"XChaCha20-Poly1305-OpenSSL", chacha20poly1305.NonceSizeX}
// CryptoCore is the low level crypto implementation.
type CryptoCore struct {
// EME is used for filename encryption.
@ -69,7 +72,7 @@ type CryptoCore struct {
//
// Note: "key" is either the scrypt hash of the password (when decrypting
// a config file) or the masterkey (when finally mounting the filesystem).
func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDecode bool) *CryptoCore {
func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool) *CryptoCore {
if len(key) != KeyLen {
log.Panicf("Unsupported key length of %d bytes", len(key))
}
@ -113,7 +116,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if IVBitLen != 128 {
log.Panicf("stupidgcm only supports 128-bit IVs, you wanted %d", IVBitLen)
}
aeadCipher = stupidgcm.New(gcmKey, forceDecode)
aeadCipher = stupidgcm.NewAES256GCM(gcmKey)
case BackendGoGCM:
goGcmBlockCipher, err := aes.NewCipher(gcmKey)
if err != nil {
@ -123,6 +126,8 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if err != nil {
log.Panic(err)
}
default:
log.Panicf("BUG: unhandled case: %v", aeadType)
}
for i := range gcmKey {
gcmKey[i] = 0
@ -147,7 +152,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
for i := range key64 {
key64[i] = 0
}
} else if aeadType == BackendXChaCha20Poly1305 {
} else if aeadType == BackendXChaCha20Poly1305 || aeadType == BackendXChaCha20Poly1305OpenSSL {
// We don't support legacy modes with XChaCha20-Poly1305
if IVBitLen != chacha20poly1305.NonceSizeX*8 {
log.Panicf("XChaCha20-Poly1305 must use 192-bit IVs, you wanted %d", IVBitLen)
@ -156,7 +161,13 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
log.Panic("XChaCha20-Poly1305 must use HKDF, but it is disabled")
}
derivedKey := hkdfDerive(key, hkdfInfoXChaChaPoly1305Content, chacha20poly1305.KeySize)
if aeadType == BackendXChaCha20Poly1305 {
aeadCipher, err = chacha20poly1305.NewX(derivedKey)
} else if aeadType == BackendXChaCha20Poly1305OpenSSL {
aeadCipher = stupidgcm.NewXchacha20poly1305(derivedKey)
} else {
log.Panicf("BUG: unhandled case: %v", aeadType)
}
if err != nil {
log.Panic(err)
}

2
internal/nametransform/diriv.go
View File

@ -67,7 +67,7 @@ func WriteDirIVAt(dirfd int) error {
iv := cryptocore.RandBytes(DirIVLen)
// 0400 permissions: gocryptfs.diriv should never be modified after creation.
// Don't use "ioutil.WriteFile", it causes trouble on NFS:
// https://github.com/rfjakob/gocryptfs/v2/commit/7d38f80a78644c8ec4900cc990bfb894387112ed
// https://github.com/rfjakob/gocryptfs/commit/7d38f80a78644c8ec4900cc990bfb894387112ed
fd, err := syscallcompat.Openat(dirfd, DirIVFilename, os.O_WRONLY|os.O_CREATE|os.O_EXCL, dirivPerms)
if err != nil {
return err

4
internal/nametransform/perms.go
View File

@ -6,14 +6,14 @@ const (
// never chmod'ed or chown'ed.
//
// Group-readable so the FS can be mounted by several users in the same group
// (see https://github.com/rfjakob/gocryptfs/v2/issues/387 ).
// (see https://github.com/rfjakob/gocryptfs/issues/387 ).
//
// Note that gocryptfs.conf is still created with 0400 permissions so the
// owner must explicitly chmod it to permit access.
//
// World-readable so an encrypted directory can be copied by the non-root
// owner when gocryptfs is running as root
// ( https://github.com/rfjakob/gocryptfs/v2/issues/539 ).
// ( https://github.com/rfjakob/gocryptfs/issues/539 ).
dirivPerms = 0444
// Permissions for gocryptfs.longname.[sha256].name files.

1
internal/stupidgcm/.gitignore vendored Normal file
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@ -0,0 +1 @@
*.o

18
internal/stupidgcm/Makefile Normal file
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@ -0,0 +1,18 @@
.PHONY: test
test: gcc
# All three ways of building this must work
go build
go build -tags without_openssl
CGO_ENABLED=0 go build -tags without_openssl
# Likewise, all three ways of testing this must work
go test -v
go test -v -tags without_openssl
CGO_ENABLED=0 go test -v -tags without_openssl
.PHONY: gcc
gcc:
gcc -Wall -Wextra -Wformat-security -Wconversion -lcrypto -c *.c
.PHONY: format
format:
clang-format --style=WebKit -i *.c *.h

54
internal/stupidgcm/chacha.go Normal file
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@ -0,0 +1,54 @@
// +build !without_openssl
package stupidgcm
import (
"crypto/cipher"
"log"
"golang.org/x/crypto/chacha20poly1305"
)
/*
#include <openssl/evp.h>
*/
import "C"
type stupidChacha20poly1305 struct {
stupidAEADCommon
}
// Verify that we satisfy the cipher.AEAD interface
var _ cipher.AEAD = &stupidChacha20poly1305{}
// _EVP_chacha20_poly1305 caches C.EVP_chacha20_poly1305() to avoid the Cgo call
// overhead for each instantiation of NewChacha20poly1305.
var _EVP_chacha20_poly1305 *C.EVP_CIPHER
func init() {
_EVP_chacha20_poly1305 = C.EVP_chacha20_poly1305()
}
// NewChacha20poly1305 returns a new instance of the OpenSSL ChaCha20-Poly1305 AEAD
// cipher ( https://www.openssl.org/docs/man1.1.1/man3/EVP_chacha20_poly1305.html ).
//
// gocryptfs only uses ChaCha20-Poly1305 as a building block for OpenSSL
// XChaCha20-Poly1305. This function is hot because it gets called once for each
// block by XChaCha20-Poly1305.
//
// Only 32-bytes keys and 12-byte IVs are supported.
func NewChacha20poly1305(key []byte) cipher.AEAD {
if len(key) != chacha20poly1305.KeySize {
log.Panicf("Only %d-byte keys are supported, you passed %d bytes", chacha20poly1305.KeySize, len(key))
}
// private copy
key2 := make([]byte, chacha20poly1305.KeySize)
copy(key2, key)
return &stupidChacha20poly1305{
stupidAEADCommon{
key: key2,
openSSLEVPCipher: _EVP_chacha20_poly1305,
nonceSize: chacha20poly1305.NonceSize,
},
}
}

70
internal/stupidgcm/common.go Normal file
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@ -0,0 +1,70 @@
// +build !without_openssl
package stupidgcm
import (
"log"
)
/*
#include <openssl/evp.h>
*/
import "C"
type stupidAEADCommon struct {
wiped bool
key []byte
openSSLEVPCipher *C.EVP_CIPHER
nonceSize int
}
// Overhead returns the number of bytes that are added for authentication.
//
// Part of the cipher.AEAD interface.
func (c *stupidAEADCommon) Overhead() int {
return tagLen
}
// NonceSize returns the required size of the nonce / IV
//
// Part of the cipher.AEAD interface.
func (c *stupidAEADCommon) NonceSize() int {
return c.nonceSize
}
// Seal encrypts "in" using "iv" and "authData" and append the result to "dst"
//
// Part of the cipher.AEAD interface.
func (c *stupidAEADCommon) Seal(dst, iv, in, authData []byte) []byte {
return openSSLSeal(c, dst, iv, in, authData)
}
// Open decrypts "in" using "iv" and "authData" and append the result to "dst"
//
// Part of the cipher.AEAD interface.
func (c *stupidAEADCommon) Open(dst, iv, in, authData []byte) ([]byte, error) {
return openSSLOpen(c, dst, iv, in, authData)
}
// Wipe tries to wipe the key from memory by overwriting it with zeros.
//
// This is not bulletproof due to possible GC copies, but
// still raises the bar for extracting the key.
func (c *stupidAEADCommon) Wipe() {
key := c.key
c.wiped = true
c.key = nil
for i := range key {
key[i] = 0
}
}
func (c *stupidAEADCommon) Wiped() bool {
if c.wiped {
return true
}
if len(c.key) != keyLen {
log.Panicf("wrong key length %d", len(c.key))
}
return false
}

59
internal/stupidgcm/doc.go Normal file
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@ -0,0 +1,59 @@
// Package stupidgcm wraps OpenSSL to provide a cipher.AEAD interface for
// authenticated encryption algorithms.
//
// The supported algorithms are:
//
// (1) AES-GCM-256 (OpenSSL EVP_aes_256_gcm)
//
// (2) ChaCha20-Poly1305 (OpenSSL EVP_chacha20_poly1305)
//
// (3) XChaCha20-Poly1305 (OpenSSL EVP_chacha20_poly1305 + Go HChaCha20)
//
// The golang.org/x/crypto libraries provides implementations for all algorithms,
// and the test suite verifies that the implementation in this package gives
// the exact same results.
//
// However, OpenSSL has optimized assembly for almost all platforms, which Go
// does not. Example for a 32-bit ARM device (Odroid XU4):
//
// $ gocrypts -speed
// gocryptfs v2.1-68-gedf9d4c.stupidchacha; go-fuse v2.1.1-0.20210825171523-3ab5d95a30ae; 2021-09-04 go1.16.7 linux/arm
// AES-GCM-256-OpenSSL 56.84 MB/s (selected in auto mode)
// AES-GCM-256-Go 16.61 MB/s
// AES-SIV-512-Go 16.49 MB/s
// XChaCha20-Poly1305-Go 39.08 MB/s (use via -xchacha flag)
// XChaCha20-Poly1305-OpenSSL 141.82 MB/s
//
// This package is "stupid" in the sense that it only supports a narrow set of
// key- and iv-lengths, and panics if it does not like what you pass it.
// See the constructor functions for which restrictions apply for each algorithm.
// Also, it is only tested for block lengths up to 5000 bytes, because this is
// what gocryptfs uses.
//
// Corrupt ciphertexts never cause a panic. Instead, ErrAuth is returned on
// decryption.
//
// XChaCha20-Poly1305
//
// The XChaCha20-Poly1305 implementation is more complicated than the others,
// because OpenSSL does not support XChaCha20-Poly1305 directly. Follow
// https://github.com/openssl/openssl/issues/5523 to get notified when it is
// accepted into OpenSSL.
//
// Fortunately, XChaCha20-Poly1305 is just ChaCha20-Poly1305 with some key+iv
// mixing using HChaCha20 in front:
//
// key (32 bytes), iv (24 bytes)
// |
// v
// HChaCha20 (provided by golang.org/x/crypto/chacha20)
// |
// v
// key2 (32 bytes), iv2 (16 bytes)
// |
// v
// ChaCha20-Poly1305 (OpenSSL EVP_chacha20_poly1305)
//
// As HChaCha20 is very fast, XChaCha20-Poly1305 gets almost the same throughput
// as ChaCha20-Poly1305 (for 4kiB blocks).
package stupidgcm

41
internal/stupidgcm/gcm.go Normal file
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@ -0,0 +1,41 @@
// +build !without_openssl
package stupidgcm
// #include <openssl/evp.h>
import "C"
import (
"crypto/cipher"
"log"
)
const (
// BuiltWithoutOpenssl indicates if openssl been disabled at compile-time
BuiltWithoutOpenssl = false
keyLen = 32
ivLen = 16
tagLen = 16
)
type stupidGCM struct {
stupidAEADCommon
}
// NewAES256GCM returns a new AES-256-GCM cipher that satisfies the cipher.AEAD interface.
//
// Only 32-bytes keys and 16-byte IVs are supported.
func NewAES256GCM(keyIn []byte) cipher.AEAD {
if len(keyIn) != keyLen {
log.Panicf("Only %d-byte keys are supported", keyLen)
}
return &stupidGCM{
stupidAEADCommon{
// Create a private copy of the key
key: append([]byte{}, keyIn...),
openSSLEVPCipher: C.EVP_aes_256_gcm(),
nonceSize: ivLen,
},
}
}

123
internal/stupidgcm/openssl.go Normal file
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@ -0,0 +1,123 @@
// +build !without_openssl
package stupidgcm
import (
"fmt"
"log"
)
/*
#include "openssl_aead.h"
#cgo pkg-config: libcrypto
*/
import "C"
func openSSLSeal(a *stupidAEADCommon, dst, iv, in, authData []byte) []byte {
if a.Wiped() {
log.Panic("BUG: tried to use wiped key")
}
if len(iv) != a.NonceSize() {
log.Panicf("Only %d-byte IVs are supported, you passed %d bytes", a.NonceSize(), len(iv))
}
// If the "dst" slice is large enough we can use it as our output buffer
outLen := len(in) + tagLen
var buf []byte
inplace := false
if cap(dst)-len(dst) >= outLen {
inplace = true
buf = dst[len(dst) : len(dst)+outLen]
} else {
buf = make([]byte, outLen)
}
res := int(C.openssl_aead_seal(a.openSSLEVPCipher,
slicePointerOrNull(in),
C.int(len(in)),
(*C.uchar)(&authData[0]),
C.int(len(authData)),
(*C.uchar)(&a.key[0]),
C.int(len(a.key)),
(*C.uchar)(&iv[0]),
C.int(len(iv)),
(*C.uchar)(&buf[0]),
C.int(len(buf))))
if res != outLen {
log.Panicf("expected length %d, got %d", outLen, res)
}
if inplace {
return dst[:len(dst)+outLen]
}
return append(dst, buf...)
}
func openSSLOpen(a *stupidAEADCommon, dst, iv, in, authData []byte) ([]byte, error) {
if a.Wiped() {
log.Panic("BUG: tried to use wiped key")
}
if len(iv) != a.NonceSize() {
log.Panicf("Only %d-byte IVs are supported, you passed %d bytes", a.NonceSize(), len(iv))
}
if len(in) < tagLen {
return nil, fmt.Errorf("stupidChacha20poly1305: input data too short (%d bytes)", len(in))
}
// If the "dst" slice is large enough we can use it as our output buffer
outLen := len(in) - tagLen
var buf []byte
inplace := false
if cap(dst)-len(dst) >= outLen {
inplace = true
buf = dst[len(dst) : len(dst)+outLen]
} else {
buf = make([]byte, len(in)-tagLen)
}
ciphertext := in[:len(in)-tagLen]
tag := in[len(in)-tagLen:]
res := int(C.openssl_aead_open(a.openSSLEVPCipher,
slicePointerOrNull(ciphertext),
C.int(len(ciphertext)),
(*C.uchar)(&authData[0]),
C.int(len(authData)),
(*C.uchar)(&tag[0]),
C.int(len(tag)),
(*C.uchar)(&a.key[0]),
C.int(len(a.key)),
(*C.uchar)(&iv[0]),
C.int(len(iv)),
slicePointerOrNull(buf),
C.int(len(buf))))
if res < 0 {
return nil, ErrAuth
}
if res != outLen {
log.Panicf("unexpected length %d", res)
}
if inplace {
return dst[:len(dst)+outLen], nil
}
return append(dst, buf...), nil
}
// slicePointerOrNull returns a C pointer to the beginning of the byte slice,
// or NULL if the byte slice is empty. This is useful for slices that can be
// empty, otherwise you can directly use "(*C.uchar)(&s[0])".
func slicePointerOrNull(s []byte) (ptr *C.uchar) {
if len(s) == 0 {
return
}
return (*C.uchar)(&s[0])
}
// This functions exists to benchmark the C call overhead from Go.
// See BenchmarkCCall for resuts.
func noopCFunction() {
C.noop_c_function()
}

185
internal/stupidgcm/openssl_aead.c Normal file
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@ -0,0 +1,185 @@
// +build !without_openssl
#include "openssl_aead.h"
#include <openssl/evp.h>
#include <stdio.h>
//#cgo pkg-config: libcrypto
static void panic(const char* const msg)
{
fprintf(stderr, "panic in C code: %s\n", msg);
__builtin_trap();
}
// We only support 16-byte tags
static const int supportedTagLen = 16;
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
int openssl_aead_seal(
const EVP_CIPHER* evpCipher,
const unsigned char* const plaintext,
const int plaintextLen,
const unsigned char* const authData,
const int authDataLen,
const unsigned char* const key,
const int keyLen,
const unsigned char* const iv,
const int ivLen,
unsigned char* const ciphertext,
const int ciphertextBufLen)
{
// Create scratch space "ctx"
EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
panic("EVP_CIPHER_CTX_new failed");
}
// Set cipher
if (EVP_EncryptInit_ex(ctx, evpCipher, NULL, NULL, NULL) != 1) {
panic("EVP_EncryptInit_ex set cipher failed");
}
// Check keyLen by trying to set it (fails if keyLen != 32)
if (EVP_CIPHER_CTX_set_key_length(ctx, keyLen) != 1) {
panic("keyLen mismatch");
}
// Set IV length so we do not depend on the default
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivLen, NULL) != 1) {
panic("EVP_CTRL_AEAD_SET_IVLEN failed");
}
// Set key and IV
if (EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv) != 1) {
panic("EVP_EncryptInit_ex set key & iv failed");
}
// Provide authentication data
int outLen = 0;
if (EVP_EncryptUpdate(ctx, NULL, &outLen, authData, authDataLen) != 1) {
panic("EVP_EncryptUpdate authData failed");
}
if (outLen != authDataLen) {
panic("EVP_EncryptUpdate authData: unexpected length");
}
// Encrypt "plaintext" into "ciphertext"
if (plaintextLen > ciphertextBufLen) {
panic("plaintext overflows output buffer");
}
if (EVP_EncryptUpdate(ctx, ciphertext, &outLen, plaintext, plaintextLen) != 1) {
panic("EVP_EncryptUpdate ciphertext failed");
}
if (outLen != plaintextLen) {
panic("EVP_EncryptUpdate ciphertext: unexpected length");
}
int ciphertextLen = outLen;
// Finalise encryption
// Normally ciphertext bytes may be written at this stage, but this does not occur in GCM mode
if (EVP_EncryptFinal_ex(ctx, ciphertext + plaintextLen, &outLen) != 1) {
panic("EVP_EncryptFinal_ex failed");
}
if (outLen != 0) {
panic("EVP_EncryptFinal_ex: unexpected length");
}
// Get MAC tag and append it to the ciphertext
if (ciphertextLen + supportedTagLen > ciphertextBufLen) {
panic("tag overflows output buffer");
}
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, supportedTagLen, ciphertext + plaintextLen) != 1) {
panic("EVP_CTRL_AEAD_GET_TAG failed");
}
ciphertextLen += supportedTagLen;
// Free scratch space
EVP_CIPHER_CTX_free(ctx);
return ciphertextLen;
}
int openssl_aead_open(
const EVP_CIPHER* evpCipher,
const unsigned char* const ciphertext,
const int ciphertextLen,
const unsigned char* const authData,
const int authDataLen,
unsigned char* const tag,
const int tagLen,
const unsigned char* const key,
const int keyLen,
const unsigned char* const iv,
const int ivLen,
unsigned char* const plaintext,
const int plaintextBufLen)
{
// Create scratch space "ctx"
EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
panic("EVP_CIPHER_CTX_new failed");
}
// Set cipher
if (EVP_DecryptInit_ex(ctx, evpCipher, NULL, NULL, NULL) != 1) {
panic("EVP_DecryptInit_ex set cipher failed");
}
// Check keyLen by trying to set it (fails if keyLen != 32)
if (EVP_CIPHER_CTX_set_key_length(ctx, keyLen) != 1) {
panic("keyLen mismatch");
}
// Set IV length so we do not depend on the default
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivLen, NULL) != 1) {
panic("EVP_CTRL_AEAD_SET_IVLEN failed");
}
// Set key and IV
if (EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv) != 1) {
panic("EVP_DecryptInit_ex set key & iv failed");
}
// Provide authentication data
int outLen = 0;
if (EVP_DecryptUpdate(ctx, NULL, &outLen, authData, authDataLen) != 1) {
panic("EVP_DecryptUpdate authData failed");
}
if (outLen != authDataLen) {
panic("EVP_DecryptUpdate authData: unexpected length");
}
// Decrypt "ciphertext" into "plaintext"
if (ciphertextLen > plaintextBufLen) {
panic("ciphertextLen overflows output buffer");
}
if (EVP_DecryptUpdate(ctx, plaintext, &outLen, ciphertext, ciphertextLen) != 1) {
panic("EVP_DecryptUpdate failed");
}
int plaintextLen = outLen;
// Check tag
if (tagLen != supportedTagLen) {
panic("unsupported tag length");
}
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, tagLen, tag) != 1) {
panic("EVP_CTRL_AEAD_SET_TAG failed");
}
if (EVP_DecryptFinal_ex(ctx, plaintext + plaintextLen, &outLen) != 1) {
// authentication failed
return -1;
}
if (outLen != 0) {
panic("EVP_EncryptFinal_ex: unexpected length");
}
/* Clean up */
EVP_CIPHER_CTX_free(ctx);
return plaintextLen;
}
// This functions exists to benchmark the C call overhead from Go.
void noop_c_function(void) {
return;
}

31
internal/stupidgcm/openssl_aead.h Normal file
View File

@ -0,0 +1,31 @@
#include <openssl/evp.h>
int openssl_aead_seal(
const EVP_CIPHER* evpCipher,
const unsigned char* const plaintext,
const int plaintextLen,
const unsigned char* const authData,
const int authDataLen,
const unsigned char* const key,
const int keyLen,
const unsigned char* const iv,
const int ivLen,
unsigned char* const ciphertext,
const int ciphertextBufLen);
int openssl_aead_open(
const EVP_CIPHER* evpCipher,
const unsigned char* const ciphertext,
const int ciphertextLen,
const unsigned char* const authData,
const int authDataLen,
unsigned char* const tag,
const int tagLen,
const unsigned char* const key,
const int keyLen,
const unsigned char* const iv,
const int ivLen,
unsigned char* const plaintext,
const int plaintextBufLen);
void noop_c_function(void);

49
internal/stupidgcm/prefer.go
View File

@ -6,7 +6,8 @@ import (
"golang.org/x/sys/cpu"
)
// PreferOpenSSL tells us if OpenSSL is faster than Go GCM on this machine.
// PreferOpenSSLAES256GCM tells us if OpenSSL AES-256-GCM is faster than Go stdlib
// on this machine.
//
// Go GCM is only faster if the CPU either:
//
@ -14,22 +15,46 @@ import (
// 2) Is ARM64 && has AES instructions && Go is v1.11 or higher
// (commit https://github.com/golang/go/commit/4f1f503373cda7160392be94e3849b0c9b9ebbda)
//
// See https://github.com/rfjakob/gocryptfs/v2/wiki/CPU-Benchmarks
// See https://github.com/rfjakob/gocryptfs/wiki/CPU-Benchmarks
// for benchmarks.
func PreferOpenSSL() bool {
func PreferOpenSSLAES256GCM() bool {
if BuiltWithoutOpenssl {
return false
}
// Safe to call on other architectures - will just read false.
if cpu.X86.HasAES || cpu.ARM64.HasAES {
// Go stdlib is probably faster
// If the CPU has AES acceleration, Go stdlib is faster
if CpuHasAES() {
return false
}
// On the Apple M1, Go stdlib is faster than OpenSSL, despite cpu.ARM64.HasAES
// reading false: https://github.com/rfjakob/gocryptfs/v2/issues/556#issuecomment-848079309
if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
return false
}
// OpenSSL is probably faster
// Otherwise OpenSSL is probably faster
return true
}
// PreferOpenSSLXchacha20poly1305 returns true if OpenSSL Xchacha20poly1305 is
// faster than Go stdlib on this machine.
func PreferOpenSSLXchacha20poly1305() bool {
if BuiltWithoutOpenssl {
return false
}
// Go x/crypto has optimized assembly for amd64:
// https://github.com/golang/crypto/blob/master/chacha20poly1305/chacha20poly1305_amd64.s
if runtime.GOARCH == "amd64" {
return false
}
// On arm64 and arm, OpenSSL is faster. Probably everwhere else too.
return true
}
// CpuHasAES tells you if the CPU we are running has AES acceleration that is
// usable by the Go crypto library.
func CpuHasAES() bool {
// Safe to call on other architectures - will just read false.
if cpu.X86.HasAES || cpu.ARM64.HasAES {
return true
}
// On the Apple M1, the CPU has AES acceleration, despite cpu.ARM64.HasAES
// reading false: https://github.com/rfjakob/gocryptfs/issues/556#issuecomment-848079309
if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
return true
}
return false
}

249
internal/stupidgcm/stupidgcm.go
View File

@ -1,249 +0,0 @@
// +build !without_openssl
// Package stupidgcm is a thin wrapper for OpenSSL's GCM encryption and
// decryption functions. It only support 32-byte keys and 16-bit IVs.
package stupidgcm
// #include <openssl/evp.h>
// #cgo pkg-config: libcrypto
import "C"
import (
"crypto/cipher"
"fmt"
"log"
"unsafe"
)
const (
// BuiltWithoutOpenssl indicates if openssl been disabled at compile-time
BuiltWithoutOpenssl = false
keyLen = 32
ivLen = 16
tagLen = 16
)
// StupidGCM implements the cipher.AEAD interface
type StupidGCM struct {
key []byte
forceDecode bool
}
// Verify that we satisfy the cipher.AEAD interface
var _ cipher.AEAD = &StupidGCM{}
// New returns a new cipher.AEAD implementation..
func New(keyIn []byte, forceDecode bool) cipher.AEAD {
if len(keyIn) != keyLen {
log.Panicf("Only %d-byte keys are supported", keyLen)
}
// Create a private copy of the key
key := append([]byte{}, keyIn...)
return &StupidGCM{key: key, forceDecode: forceDecode}
}
// NonceSize returns the required size of the nonce / IV.
func (g *StupidGCM) NonceSize() int {
return ivLen
}
// Overhead returns the number of bytes that are added for authentication.
func (g *StupidGCM) Overhead() int {
return tagLen
}
// Seal encrypts "in" using "iv" and "authData" and append the result to "dst"
func (g *StupidGCM) Seal(dst, iv, in, authData []byte) []byte {
if len(iv) != ivLen {
log.Panicf("Only %d-byte IVs are supported", ivLen)
}
if len(in) == 0 {
log.Panic("Zero-length input data is not supported")
}
if len(g.key) != keyLen {
log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
}
// If the "dst" slice is large enough we can use it as our output buffer
outLen := len(in) + tagLen
var buf []byte
inplace := false
if cap(dst)-len(dst) >= outLen {
inplace = true
buf = dst[len(dst) : len(dst)+outLen]
} else {
buf = make([]byte, outLen)
}
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
// Create scratch space "context"
ctx := C.EVP_CIPHER_CTX_new()
if ctx == nil {
log.Panic("EVP_CIPHER_CTX_new failed")
}
// Set cipher to AES-256
if C.EVP_EncryptInit_ex(ctx, C.EVP_aes_256_gcm(), nil, nil, nil) != 1 {
log.Panic("EVP_EncryptInit_ex I failed")
}
// Use 16-byte IV
if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_SET_IVLEN, ivLen, nil) != 1 {
log.Panic("EVP_CIPHER_CTX_ctrl EVP_CTRL_GCM_SET_IVLEN failed")
}
// Set key and IV
if C.EVP_EncryptInit_ex(ctx, nil, nil, (*C.uchar)(&g.key[0]), (*C.uchar)(&iv[0])) != 1 {
log.Panic("EVP_EncryptInit_ex II failed")
}
// Provide authentication data
var resultLen C.int
if C.EVP_EncryptUpdate(ctx, nil, &resultLen, (*C.uchar)(&authData[0]), C.int(len(authData))) != 1 {
log.Panic("EVP_EncryptUpdate authData failed")
}
if int(resultLen) != len(authData) {
log.Panicf("Unexpected length %d", resultLen)
}
// Encrypt "in" into "buf"
if C.EVP_EncryptUpdate(ctx, (*C.uchar)(&buf[0]), &resultLen, (*C.uchar)(&in[0]), C.int(len(in))) != 1 {
log.Panic("EVP_EncryptUpdate failed")
}
if int(resultLen) != len(in) {
log.Panicf("Unexpected length %d", resultLen)
}
// Finalise encryption
// Because GCM is a stream encryption, this will not write out any data.
dummy := make([]byte, 16)
if C.EVP_EncryptFinal_ex(ctx, (*C.uchar)(&dummy[0]), &resultLen) != 1 {
log.Panic("EVP_EncryptFinal_ex failed")
}
if resultLen != 0 {
log.Panicf("Unexpected length %d", resultLen)
}
// Get GMAC tag and append it to the ciphertext in "buf"
if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_GET_TAG, tagLen, (unsafe.Pointer)(&buf[len(in)])) != 1 {
log.Panic("EVP_CIPHER_CTX_ctrl EVP_CTRL_GCM_GET_TAG failed")
}
// Free scratch space
C.EVP_CIPHER_CTX_free(ctx)
if inplace {
return dst[:len(dst)+outLen]
}
return append(dst, buf...)
}
// Open decrypts "in" using "iv" and "authData" and append the result to "dst"
func (g *StupidGCM) Open(dst, iv, in, authData []byte) ([]byte, error) {
if len(iv) != ivLen {
log.Panicf("Only %d-byte IVs are supported", ivLen)
}
if len(g.key) != keyLen {
log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
}
if len(in) <= tagLen {
return nil, fmt.Errorf("stupidgcm: input data too short (%d bytes)", len(in))
}
// If the "dst" slice is large enough we can use it as our output buffer
outLen := len(in) - tagLen
var buf []byte
inplace := false
if cap(dst)-len(dst) >= outLen {
inplace = true
buf = dst[len(dst) : len(dst)+outLen]
} else {
buf = make([]byte, len(in)-tagLen)
}
ciphertext := in[:len(in)-tagLen]
tag := in[len(in)-tagLen:]
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
// Create scratch space "context"
ctx := C.EVP_CIPHER_CTX_new()
if ctx == nil {
log.Panic("EVP_CIPHER_CTX_new failed")
}
// Set cipher to AES-256
if C.EVP_DecryptInit_ex(ctx, C.EVP_aes_256_gcm(), nil, nil, nil) != 1 {
log.Panic("EVP_DecryptInit_ex I failed")
}
// Use 16-byte IV
if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_SET_IVLEN, ivLen, nil) != 1 {
log.Panic("EVP_CIPHER_CTX_ctrl EVP_CTRL_GCM_SET_IVLEN failed")
}
// Set key and IV
if C.EVP_DecryptInit_ex(ctx, nil, nil, (*C.uchar)(&g.key[0]), (*C.uchar)(&iv[0])) != 1 {
log.Panic("EVP_DecryptInit_ex II failed")
}
// Set expected GMAC tag
if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_SET_TAG, tagLen, (unsafe.Pointer)(&tag[0])) != 1 {
log.Panic("EVP_CIPHER_CTX_ctrl failed")
}
// Provide authentication data
var resultLen C.int
if C.EVP_DecryptUpdate(ctx, nil, &resultLen, (*C.uchar)(&authData[0]), C.int(len(authData))) != 1 {
log.Panic("EVP_DecryptUpdate authData failed")
}
if int(resultLen) != len(authData) {
log.Panicf("Unexpected length %d", resultLen)
}
// Decrypt "ciphertext" into "buf"
if C.EVP_DecryptUpdate(ctx, (*C.uchar)(&buf[0]), &resultLen, (*C.uchar)(&ciphertext[0]), C.int(len(ciphertext))) != 1 {
log.Panic("EVP_DecryptUpdate failed")
}
if int(resultLen) != len(ciphertext) {
log.Panicf("Unexpected length %d", resultLen)
}
// Check GMAC
dummy := make([]byte, 16)
res := C.EVP_DecryptFinal_ex(ctx, (*C.uchar)(&dummy[0]), &resultLen)
if resultLen != 0 {
log.Panicf("Unexpected length %d", resultLen)
}
// Free scratch space
C.EVP_CIPHER_CTX_free(ctx)
if res != 1 {
// The error code must always be checked by the calling function, because the decrypted buffer
// may contain corrupted data that we are returning in case the user forced reads
if g.forceDecode {
return append(dst, buf...), ErrAuth
}
return nil, ErrAuth
}
if inplace {
return dst[:len(dst)+outLen], nil
}
return append(dst, buf...), nil
}
// Wipe tries to wipe the AES key from memory by overwriting it with zeros
// and setting the reference to nil.
//
// This is not bulletproof due to possible GC copies, but
// still raises to bar for extracting the key.
func (g *StupidGCM) Wipe() {
for i := range g.key {
g.key[i] = 0
}
g.key = nil
}

117
internal/stupidgcm/xchacha.go Normal file
View File

@ -0,0 +1,117 @@
// +build !without_openssl
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Copied from
// https://github.com/golang/crypto/blob/32db794688a5a24a23a43f2a984cecd5b3d8da58/chacha20poly1305/xchacha20poly1305.go
// and adapted for stupidgcm by @rfjakob.
package stupidgcm
import (
"crypto/cipher"
"errors"
"log"
"golang.org/x/crypto/chacha20"
"golang.org/x/crypto/chacha20poly1305"
)
type stupidXchacha20poly1305 struct {
// array instead of byte slice like
// `struct xchacha20poly1305` in x/crypto/chacha20poly1305
key [chacha20poly1305.KeySize]byte
wiped bool
}
// NewXchacha20poly1305 returns a XChaCha20-Poly1305 cipher that satisfied the
// cipher.AEAD interface.
//
// XChaCha20-Poly1305 is a ChaCha20-Poly1305 variant that takes a longer nonce,
// suitable to be generated randomly without risk of collisions. It should be
// preferred when nonce uniqueness cannot be trivially ensured, or whenever
// nonces are randomly generated.
//
// Only 32-bytes keys and 24-byte IVs are supported.
func NewXchacha20poly1305(key []byte) cipher.AEAD {
if len(key) != chacha20poly1305.KeySize {
log.Panic("bad key length")
}
ret := new(stupidXchacha20poly1305)
copy(ret.key[:], key)
return ret
}
func (*stupidXchacha20poly1305) NonceSize() int {
return chacha20poly1305.NonceSizeX
}
func (*stupidXchacha20poly1305) Overhead() int {
return tagLen
}
func (x *stupidXchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []byte) []byte {
if x.wiped {
log.Panic("BUG: tried to use wiped key")
}
if len(nonce) != chacha20poly1305.NonceSizeX {
log.Panic("bad nonce length passed to Seal")
}
// XChaCha20-Poly1305 technically supports a 64-bit counter, so there is no
// size limit. However, since we reuse the ChaCha20-Poly1305 implementation,
// the second half of the counter is not available. This is unlikely to be
// an issue because the cipher.AEAD API requires the entire message to be in
// memory, and the counter overflows at 256 GB.
if uint64(len(plaintext)) > (1<<38)-64 {
log.Panic("plaintext too large")
}
hKey, _ := chacha20.HChaCha20(x.key[:], nonce[0:16])
c := NewChacha20poly1305(hKey).(*stupidChacha20poly1305)
defer c.Wipe()
// The first 4 bytes of the final nonce are unused counter space.
cNonce := make([]byte, chacha20poly1305.NonceSize)
copy(cNonce[4:12], nonce[16:24])
return c.Seal(dst, cNonce[:], plaintext, additionalData)
}
func (x *stupidXchacha20poly1305) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
if x.wiped {
log.Panic("BUG: tried to use wiped key")
}
if len(nonce) != chacha20poly1305.NonceSizeX {
log.Panic("bad nonce length passed to Open")
}
if len(ciphertext) < 16 {
return nil, errors.New("message too short")
}
if uint64(len(ciphertext)) > (1<<38)-48 {
log.Panic("ciphertext too large")
}
hKey, _ := chacha20.HChaCha20(x.key[:], nonce[0:16])
c := NewChacha20poly1305(hKey).(*stupidChacha20poly1305)
defer c.Wipe()
// The first 4 bytes of the final nonce are unused counter space.
cNonce := make([]byte, chacha20poly1305.NonceSize)
copy(cNonce[4:12], nonce[16:24])
return c.Open(dst, cNonce[:], ciphertext, additionalData)
}
// Wipe tries to wipe the key from memory by overwriting it with zeros.
//
// This is not bulletproof due to possible GC copies, but
// still raises the bar for extracting the key.
func (g *stupidXchacha20poly1305) Wipe() {
g.wiped = true
for i := range g.key {
g.key[i] = 0
}
}

2
internal/syscallcompat/eintr.go
View File

@ -12,7 +12,7 @@ import (
// https://github.com/golang/go/blob/d2a80f3fb5b44450e0b304ac5a718f99c053d82a/src/os/file_posix.go#L243
//
// This is needed because CIFS throws lots of EINTR errors:
// https://github.com/rfjakob/gocryptfs/v2/issues/483
// https://github.com/rfjakob/gocryptfs/issues/483
//
// Don't use retryEINTR() with syscall.Close()!
// See https://code.google.com/p/chromium/issues/detail?id=269623 .

2
internal/syscallcompat/getdents_linux.go
View File

@ -19,7 +19,7 @@ const sizeofDirent = int(unsafe.Sizeof(unix.Dirent{}))
// maxReclen sanity check: Reclen should never be larger than this.
// Due to padding between entries, it is 280 even on 32-bit architectures.
// See https://github.com/rfjakob/gocryptfs/v2/issues/197 for details.
// See https://github.com/rfjakob/gocryptfs/issues/197 for details.
const maxReclen = 280
type DirEntry struct {

2
internal/syscallcompat/sys_linux.go
View File

@ -35,7 +35,7 @@ func EnospcPrealloc(fd int, off int64, len int64) (err error) {
}
if err == syscall.EOPNOTSUPP {
// ZFS and ext3 do not support fallocate. Warn but continue anyway.
// https://github.com/rfjakob/gocryptfs/v2/issues/22
// https://github.com/rfjakob/gocryptfs/issues/22
return nil
}
return err

3
main.go
View File

@ -1,3 +1,6 @@
// gocryptfs is an encrypted overlay filesystem written in Go.
// See README.md ( https://github.com/rfjakob/gocryptfs/blob/master/README.md )
// and the official website ( https://nuetzlich.net/gocryptfs/ ) for details.
package main
func main() {}

38
volume.go
View File

@ -64,18 +64,25 @@ func registerNewVolume(rootCipherDir string, masterkey []byte, cf *configfile.Co
newVolume.plainTextNames = cf.IsFeatureFlagSet(configfile.FlagPlaintextNames)
// Init crypto backend
cryptoBackend := cryptocore.BackendGoGCM
if cf.IsFeatureFlagSet(configfile.FlagAESSIV) {
cryptoBackend = cryptocore.BackendAESSIV
} else if stupidgcm.PreferOpenSSL() {
cryptoBackend, err := cf.ContentEncryption()
if err != nil {
return -1
}
if cryptoBackend == cryptocore.BackendXChaCha20Poly1305 && stupidgcm.PreferOpenSSLXchacha20poly1305() {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305OpenSSL
} else if cryptoBackend == cryptocore.BackendGoGCM && stupidgcm.PreferOpenSSLAES256GCM() {
cryptoBackend = cryptocore.BackendOpenSSL
}
forcedecode := false
newVolume.cryptoCore = cryptocore.New(masterkey, cryptoBackend, contentenc.DefaultIVBits, true, forcedecode)
newVolume.contentEnc = contentenc.New(newVolume.cryptoCore, contentenc.DefaultBS, forcedecode)
newVolume.cryptoCore = cryptocore.New(masterkey, cryptoBackend, cryptoBackend.NonceSize*8, cf.IsFeatureFlagSet(configfile.FlagHKDF))
newVolume.contentEnc = contentenc.New(newVolume.cryptoCore, contentenc.DefaultBS)
var badname []string
newVolume.nameTransform = nametransform.New(newVolume.cryptoCore.EMECipher, true, true, badname, false)
newVolume.nameTransform = nametransform.New(
newVolume.cryptoCore.EMECipher,
true,
cf.IsFeatureFlagSet(configfile.FlagRaw64),
badname,
!cf.IsFeatureFlagSet(configfile.FlagDirIV),
)
//copying rootCipherDir
var grcd strings.Builder
@ -155,7 +162,16 @@ func gcf_change_password(rootCipherDir string, oldPassword, givenScryptHash, new
}
//export gcf_create_volume
func gcf_create_volume(rootCipherDir string, password []byte, plaintextNames bool, logN int, creator string) bool {
func gcf_create_volume(rootCipherDir string, password []byte, plaintextNames bool, xchacha int8, logN int, creator string) bool {
var useXChaCha bool
switch xchacha {
case 1:
useXChaCha = true
case 0:
useXChaCha = false
default:
useXChaCha = !stupidgcm.CpuHasAES()
}
err := configfile.Create(&configfile.CreateArgs{
Filename: filepath.Join(rootCipherDir, configfile.ConfDefaultName),
Password: password,
@ -164,7 +180,7 @@ func gcf_create_volume(rootCipherDir string, password []byte, plaintextNames boo
Creator: creator,
AESSIV: false,
DeterministicNames: false,
XChaCha20Poly1305: false,
XChaCha20Poly1305: useXChaCha,
})
if err == nil {
if plaintextNames {