Switch to external libgocryptfs

This commit is contained in:
Matéo Duparc 2021-06-11 16:27:08 +02:00
parent 5da1c05c7b
commit ae93d78615
Signed by: hardcoresushi
GPG Key ID: 007F84120107191E
73 changed files with 26 additions and 6035 deletions

3
.gitmodules vendored Normal file
View File

@ -0,0 +1,3 @@
[submodule "app/libgocryptfs"]
path = app/libgocryptfs
url = https://forge.chapril.org/hardcoresushi/libgocryptfs.git

1
app/libgocryptfs Submodule

@ -0,0 +1 @@
Subproject commit 847d4fa7817c84fe1b78726f031172ea508dab19

View File

@ -1,4 +0,0 @@
openssl*
lib
include
build

View File

@ -1,75 +0,0 @@
#!/bin/bash
if [ -z ${ANDROID_NDK_HOME+x} ]; then
echo "Error: \$ANDROID_NDK_HOME is not defined."
elif [ -z ${OPENSSL_PATH+x} ]; then
echo "Error: \$OPENSSL_PATH is not defined."
else
NDK_BIN_PATH="$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin"
declare -a ABIs=("x86_64" "arm64-v8a" "armeabi-v7a")
compile_openssl(){
if [ ! -d "./lib/$1" ]; then
if [ "$1" = "x86_64" ]; then
OPENSSL_ARCH="android-x86_64"
elif [ "$1" = "arm64-v8a" ]; then
OPENSSL_ARCH="android-arm64"
elif [ "$1" = "armeabi-v7a" ]; then
OPENSSL_ARCH="android-arm"
else
echo "Invalid ABI: $1"
exit
fi
export CFLAGS=-D__ANDROID_API__=21
export PATH=$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin:$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:$PATH
(cd "$OPENSSL_PATH" && if [ -f "Makefile" ]; then make clean; fi && ./Configure $OPENSSL_ARCH -D__ANDROID_API__=21 no-stdio && make build_libs)
mkdir -p "./lib/$1" && cp "$OPENSSL_PATH/libcrypto.a" "$OPENSSL_PATH/libssl.a" "./lib/$1"
mkdir -p "./include/$1" && cp -r "$OPENSSL_PATH"/include/* "./include/$1/"
fi
}
compile_for_arch(){
compile_openssl $1
MAIN_PACKAGE="main.go"
if [ "$1" = "x86_64" ]; then
CFN="x86_64-linux-android21-clang"
elif [ "$1" = "arm64-v8a" ]; then
CFN="aarch64-linux-android21-clang"
export GOARCH=arm64
export GOARM=7
elif [ "$1" = "armeabi-v7a" ]; then
CFN="armv7a-linux-androideabi21-clang"
export GOARCH=arm
export GOARM=7
MAIN_PACKAGE="main32.go"
#patch arch specific code
sed "s/C.malloc(C.ulong/C.malloc(C.uint/g" main.go > $MAIN_PACKAGE
sed -i "s/st.Mtim.Sec/int64(st.Mtim.Sec)/g" $MAIN_PACKAGE
else
echo "Invalid ABI: $1"
exit
fi
export CC="$NDK_BIN_PATH/$CFN"
export CXX="$NDK_BIN_PATH/$CFN++"
export CGO_ENABLED=1
export GOOS=android
export CGO_CFLAGS="-I ${PWD}/include/$1"
export CGO_LDFLAGS="-Wl,-soname=libgocryptfs.so -L${PWD}/lib/$1"
go build -o build/$1/libgocryptfs.so -buildmode=c-shared $MAIN_PACKAGE
if [ $MAIN_PACKAGE = "main32.go" ]; then
rm $MAIN_PACKAGE
fi
}
if [ "$#" -eq 1 ]; then
compile_for_arch $1
else
for abi in ${ABIs[@]}; do
echo "Compiling for $abi..."
compile_for_arch $abi
done
fi
echo "Done."
fi

View File

@ -1,168 +0,0 @@
// Package cryptocore wraps OpenSSL and Go GCM crypto and provides
// a nonce generator.
package cryptocore
import (
"crypto/aes"
"crypto/cipher"
"crypto/sha512"
"fmt"
"log"
"runtime"
"../eme"
"../siv_aead"
"../stupidgcm"
)
const (
// KeyLen is the cipher key length in bytes. 32 for AES-256.
KeyLen = 32
// AuthTagLen is the length of a GCM auth tag in bytes.
AuthTagLen = 16
)
// AEADTypeEnum indicates the type of AEAD backend in use.
type AEADTypeEnum int
const (
// BackendOpenSSL specifies the OpenSSL backend.
BackendOpenSSL AEADTypeEnum = 3
// BackendGoGCM specifies the Go based GCM backend.
BackendGoGCM AEADTypeEnum = 4
// BackendAESSIV specifies an AESSIV backend.
BackendAESSIV AEADTypeEnum = 5
)
// CryptoCore is the low level crypto implementation.
type CryptoCore struct {
// EME is used for filename encryption.
EMECipher *eme.EMECipher
// GCM or AES-SIV. This is used for content encryption.
AEADCipher cipher.AEAD
// Which backend is behind AEADCipher?
AEADBackend AEADTypeEnum
// GCM needs unique IVs (nonces)
IVGenerator *nonceGenerator
IVLen int
}
// New returns a new CryptoCore object or panics.
//
// Even though the "GCMIV128" feature flag is now mandatory, we must still
// support 96-bit IVs here because they were used for encrypting the master
// key in gocryptfs.conf up to gocryptfs v1.2. v1.3 switched to 128 bits.
//
// 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 {
if len(key) != KeyLen {
log.Panic(fmt.Sprintf("Unsupported key length %d", len(key)))
}
// We want the IV size in bytes
IVLen := IVBitLen / 8
// Initialize EME for filename encryption.
var emeCipher *eme.EMECipher
var err error
{
var emeBlockCipher cipher.Block
if useHKDF {
emeKey := HkdfDerive(key, HkdfInfoEMENames, KeyLen)
emeBlockCipher, err = aes.NewCipher(emeKey)
for i := range emeKey {
emeKey[i] = 0
}
} else {
emeBlockCipher, err = aes.NewCipher(key)
}
if err != nil {
log.Panic(err)
}
emeCipher = eme.New(emeBlockCipher)
}
// Initialize an AEAD cipher for file content encryption.
var aeadCipher cipher.AEAD
if aeadType == BackendOpenSSL || aeadType == BackendGoGCM {
var gcmKey []byte
if useHKDF {
gcmKey = HkdfDerive(key, hkdfInfoGCMContent, KeyLen)
} else {
gcmKey = append([]byte{}, key...)
}
switch aeadType {
case BackendOpenSSL:
if IVLen != 16 {
log.Panic("stupidgcm only supports 128-bit IVs")
}
aeadCipher = stupidgcm.New(gcmKey, forceDecode)
case BackendGoGCM:
goGcmBlockCipher, err := aes.NewCipher(gcmKey)
if err != nil {
log.Panic(err)
}
aeadCipher, err = cipher.NewGCMWithNonceSize(goGcmBlockCipher, IVLen)
if err != nil {
log.Panic(err)
}
}
for i := range gcmKey {
gcmKey[i] = 0
}
} else if aeadType == BackendAESSIV {
if IVLen != 16 {
// SIV supports any nonce size, but we only use 16.
log.Panic("AES-SIV must use 16-byte nonces")
}
// AES-SIV uses 1/2 of the key for authentication, 1/2 for
// encryption, so we need a 64-bytes key for AES-256. Derive it from
// the 32-byte master key using HKDF, or, for older filesystems, with
// SHA256.
var key64 []byte
if useHKDF {
key64 = HkdfDerive(key, hkdfInfoSIVContent, siv_aead.KeyLen)
} else {
s := sha512.Sum512(key)
key64 = s[:]
}
aeadCipher = siv_aead.New(key64)
for i := range key64 {
key64[i] = 0
}
} else {
log.Panic("unknown backend cipher")
}
return &CryptoCore{
EMECipher: emeCipher,
AEADCipher: aeadCipher,
AEADBackend: aeadType,
IVGenerator: &nonceGenerator{nonceLen: IVLen},
IVLen: IVLen,
}
}
type wiper interface {
Wipe()
}
// Wipe tries to wipe secret keys from memory by overwriting them with zeros
// and/or setting references to nil.
//
// This is not bulletproof due to possible GC copies, but
// still raises to bar for extracting the key.
func (c *CryptoCore) Wipe() {
be := c.AEADBackend
if be == BackendOpenSSL || be == BackendAESSIV {
// We don't use "x, ok :=" because we *want* to crash loudly if the
// type assertion fails.
w := c.AEADCipher.(wiper)
w.Wipe()
}
// We have no access to the keys (or key-equivalents) stored inside the
// Go stdlib. Best we can is to nil the references and force a GC.
c.AEADCipher = nil
c.EMECipher = nil
runtime.GC()
}

View File

@ -1,29 +0,0 @@
package cryptocore
import (
"crypto/sha256"
"log"
"golang.org/x/crypto/hkdf"
)
const (
// "info" data that HKDF mixes into the generated key to make it unique.
// For convenience, we use a readable string.
HkdfInfoEMENames = "EME filename encryption"
hkdfInfoGCMContent = "AES-GCM file content encryption"
hkdfInfoSIVContent = "AES-SIV file content encryption"
)
// hkdfDerive derives "outLen" bytes from "masterkey" and "info" using
// HKDF-SHA256 (RFC 5869).
// It returns the derived bytes or panics.
func HkdfDerive(masterkey []byte, info string, outLen int) (out []byte) {
h := hkdf.New(sha256.New, masterkey, nil, []byte(info))
out = make([]byte, outLen)
n, err := h.Read(out)
if n != outLen || err != nil {
log.Panicf("hkdfDerive: hkdf read failed, got %d bytes, error: %v", n, err)
}
return out
}

View File

@ -1,32 +0,0 @@
package cryptocore
import (
"crypto/rand"
"encoding/binary"
"log"
)
// RandBytes gets "n" random bytes from /dev/urandom or panics
func RandBytes(n int) []byte {
b := make([]byte, n)
_, err := rand.Read(b)
if err != nil {
log.Panic("Failed to read random bytes: " + err.Error())
}
return b
}
// RandUint64 returns a secure random uint64
func RandUint64() uint64 {
b := RandBytes(8)
return binary.BigEndian.Uint64(b)
}
type nonceGenerator struct {
nonceLen int // bytes
}
// Get a random "nonceLen"-byte nonce
func (n *nonceGenerator) Get() []byte {
return randPrefetcher.read(n.nonceLen)
}

View File

@ -1,55 +0,0 @@
package cryptocore
import (
"bytes"
"log"
"sync"
)
// Number of bytes to prefetch.
// 512 looks like a good compromise between throughput and latency - see
// randsize_test.go for numbers.
const prefetchN = 512
func init() {
randPrefetcher.refill = make(chan []byte)
go randPrefetcher.refillWorker()
}
type randPrefetcherT struct {
sync.Mutex
buf bytes.Buffer
refill chan []byte
}
func (r *randPrefetcherT) read(want int) (out []byte) {
out = make([]byte, want)
r.Lock()
// Note: don't use defer, it slows us down!
have, err := r.buf.Read(out)
if have == want && err == nil {
r.Unlock()
return out
}
// Buffer was empty -> re-fill
fresh := <-r.refill
if len(fresh) != prefetchN {
log.Panicf("randPrefetcher: refill: got %d bytes instead of %d", len(fresh), prefetchN)
}
r.buf.Reset()
r.buf.Write(fresh)
have, err = r.buf.Read(out)
if have != want || err != nil {
log.Panicf("randPrefetcher could not satisfy read: have=%d want=%d err=%v", have, want, err)
}
r.Unlock()
return out
}
func (r *randPrefetcherT) refillWorker() {
for {
r.refill <- RandBytes(prefetchN)
}
}
var randPrefetcher randPrefetcherT

View File

@ -1,11 +0,0 @@
language: go
go:
- 1.11.x # Debian 10 "Buster"
- 1.12.x # Ubuntu 19.10
- 1.13.x # Debian 11 "Bullseye"
- stable
script:
- go build
- ./test.bash

View File

@ -1,21 +0,0 @@
The MIT License (MIT)
Copyright (c) 2015 Jakob Unterwurzacher
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

View File

@ -1,111 +0,0 @@
EME for Go [![Build Status](https://travis-ci.org/rfjakob/eme.svg?branch=master)](https://travis-ci.org/rfjakob/eme) [![GoDoc](https://godoc.org/github.com/rfjakob/eme?status.svg)](https://godoc.org/github.com/rfjakob/eme) ![MIT License](https://img.shields.io/badge/license-MIT-blue.svg)
==========
**EME** (ECB-Mix-ECB or, clearer, **Encrypt-Mix-Encrypt**) is a wide-block
encryption mode developed by Halevi
and Rogaway in 2003 [[eme]](#eme).
EME uses multiple invocations of a block cipher to construct a new
cipher of bigger block size (in multiples of 16 bytes, up to 2048 bytes).
Quoting from the original [[eme]](#eme) paper:
> We describe a block-cipher mode of operation, EME, that turns an n-bit block cipher into
> a tweakable enciphering scheme that acts on strings of mn bits, where m ∈ [1..n]. The mode is
> parallelizable, but as serial-efficient as the non-parallelizable mode CMC [6]. EME can be used
> to solve the disk-sector encryption problem. The algorithm entails two layers of ECB encryption
> and a “lightweight mixing” in between. We prove EME secure, in the reduction-based sense of
> modern cryptography.
Figure 2 from the [[eme]](#eme) paper shows an overview of the transformation:
[![Figure 2 from [eme]](paper-eme-fig2.png)](#)
This is an implementation of EME in Go, complete with test vectors from IEEE [[p1619-2]](#p1619-2)
and Halevi [[eme-32-testvec]](#eme-32-testvec).
It has no dependencies outside the standard library.
Is it patentend?
----------------
In 2007, the UC Davis has decided to abandon [[patabandon]](#patabandon)
the patent application [[patappl]](#patappl) for EME.
Related algorithms
------------------
**EME-32** is EME with the cipher set to AES and the length set to 512.
That is, EME-32 [[eme-32-pdf]](#eme-32-pdf) is a subset of EME.
**EME2**, also known as EME\* [[emestar]](#emestar), is an extended version of EME
that has built-in handling for data that is not a multiple of 16 bytes
long.
EME2 has been selected for standardization in IEEE P1619.2 [[p1619.2]](#p1619.2).
References
----------
#### [eme]
*A Parallelizable Enciphering Mode*
Shai Halevi, Phillip Rogaway, 28 Jul 2003
https://eprint.iacr.org/2003/147.pdf
Note: This is the original EME paper. EME is specified for an arbitrary
number of block-cipher blocks. EME-32 is a concrete implementation of
EME with a fixed length of 32 AES blocks.
#### [eme-32-email]
*Re: EME-32-AES with editorial comments*
Shai Halevi, 07 Jun 2005
http://grouper.ieee.org/groups/1619/email/msg00310.html
#### [eme-32-pdf]
*Draft Standard for Tweakable Wide-block Encryption*
Shai Halevi, 02 June 2005
http://grouper.ieee.org/groups/1619/email/pdf00020.pdf
Note: This is the latest version of the EME-32 draft that I could find. It
includes test vectors and C source code.
#### [eme-32-testvec]
*Re: Test vectors for LRW and EME*
Shai Halevi, 16 Nov 2004
http://grouper.ieee.org/groups/1619/email/msg00218.html
#### [emestar]
*EME\*: extending EME to handle arbitrary-length messages with associated data*
Shai Halevi, 27 May 2004
https://eprint.iacr.org/2004/125.pdf
#### [patabandon]
*Re: [P1619-2] Non-awareness patent statement made by UC Davis*
Mat Ball, 26 Nov 2007
http://grouper.ieee.org/groups/1619/email-2/msg00005.html
#### [patappl]
*Block cipher mode of operation for constructing a wide-blocksize block cipher from a conventional block cipher*
US patent application US20040131182
http://www.google.com/patents/US20040131182
#### [p1619-2]
*IEEE P1619.2™/D9 Draft Standard for Wide-Block Encryption for Shared Storage Media*
IEEE, Dec 2008
http://siswg.net/index2.php?option=com_docman&task=doc_view&gid=156&Itemid=41
Note: This is a draft version. The final version is not freely available
and must be bought from IEEE.
Package Changelog
-----------------
v1.1.1, 2020-04-13
* Update `go vet` call in `test.bash` to work on recent Go versions
* No code changes
v1.1, 2017-03-05
* Add eme.New() / \*EMECipher convenience wrapper
* Improve panic message and parameter wording
v1.0, 2015-12-08
* Stable release

View File

@ -1,3 +0,0 @@
#!/bin/bash -eu
go test -bench=.

View File

@ -1,206 +0,0 @@
// EME (ECB-Mix-ECB or, clearer, Encrypt-Mix-Encrypt) is a wide-block
// encryption mode developed by Halevi and Rogaway.
//
// It was presented in the 2003 paper "A Parallelizable Enciphering Mode" by
// Halevi and Rogaway.
//
// EME uses multiple invocations of a block cipher to construct a new cipher
// of bigger block size (in multiples of 16 bytes, up to 2048 bytes).
package eme
import (
"crypto/cipher"
"log"
)
type directionConst bool
const (
// Encrypt "inputData"
DirectionEncrypt = directionConst(true)
// Decrypt "inputData"
DirectionDecrypt = directionConst(false)
)
// multByTwo - GF multiplication as specified in the EME-32 draft
func multByTwo(out []byte, in []byte) {
if len(in) != 16 {
panic("len must be 16")
}
tmp := make([]byte, 16)
tmp[0] = 2 * in[0]
if in[15] >= 128 {
tmp[0] = tmp[0] ^ 135
}
for j := 1; j < 16; j++ {
tmp[j] = 2 * in[j]
if in[j-1] >= 128 {
tmp[j] += 1
}
}
copy(out, tmp)
}
func xorBlocks(out []byte, in1 []byte, in2 []byte) {
if len(in1) != len(in2) {
log.Panicf("len(in1)=%d is not equal to len(in2)=%d", len(in1), len(in2))
}
for i := range in1 {
out[i] = in1[i] ^ in2[i]
}
}
// aesTransform - encrypt or decrypt (according to "direction") using block
// cipher "bc" (typically AES)
func aesTransform(dst []byte, src []byte, direction directionConst, bc cipher.Block) {
if direction == DirectionEncrypt {
bc.Encrypt(dst, src)
return
} else if direction == DirectionDecrypt {
bc.Decrypt(dst, src)
return
}
}
// tabulateL - calculate L_i for messages up to a length of m cipher blocks
func tabulateL(bc cipher.Block, m int) [][]byte {
/* set L0 = 2*AESenc(K; 0) */
eZero := make([]byte, 16)
Li := make([]byte, 16)
bc.Encrypt(Li, eZero)
LTable := make([][]byte, m)
// Allocate pool once and slice into m pieces in the loop
pool := make([]byte, m*16)
for i := 0; i < m; i++ {
multByTwo(Li, Li)
LTable[i] = pool[i*16 : (i+1)*16]
copy(LTable[i], Li)
}
return LTable
}
// Transform - EME-encrypt or EME-decrypt, according to "direction"
// (defined in the constants DirectionEncrypt and DirectionDecrypt).
// The data in "inputData" is en- or decrypted with the block ciper "bc" under
// "tweak" (also known as IV).
//
// The tweak is used to randomize the encryption in the same way as an
// IV. A use of this encryption mode envisioned by the authors of the
// algorithm was to encrypt each sector of a disk, with the tweak
// being the sector number. If you encipher the same data with the
// same tweak you will get the same ciphertext.
//
// The result is returned in a freshly allocated slice of the same
// size as inputData.
//
// Limitations:
// * The block cipher must have block size 16 (usually AES).
// * The size of "tweak" must be 16
// * "inputData" must be a multiple of 16 bytes long
// If any of these pre-conditions are not met, the function will panic.
//
// Note that you probably don't want to call this function directly and instead
// use eme.New(), which provides conventient wrappers.
func Transform(bc cipher.Block, tweak []byte, inputData []byte, direction directionConst) []byte {
// In the paper, the tweak is just called "T". Call it the same here to
// make following the paper easy.
T := tweak
// In the paper, the plaintext data is called "P" and the ciphertext is
// called "C". Because encryption and decryption are virtually identical,
// we share the code and always call the input data "P" and the output data
// "C", regardless of the direction.
P := inputData
if bc.BlockSize() != 16 {
log.Panicf("Using a block size other than 16 is not implemented")
}
if len(T) != 16 {
log.Panicf("Tweak must be 16 bytes long, is %d", len(T))
}
if len(P)%16 != 0 {
log.Panicf("Data P must be a multiple of 16 long, is %d", len(P))
}
m := len(P) / 16
if m == 0 || m > 16*8 {
log.Panicf("EME operates on 1 to %d block-cipher blocks, you passed %d", 16*8, m)
}
C := make([]byte, len(P))
LTable := tabulateL(bc, m)
PPj := make([]byte, 16)
for j := 0; j < m; j++ {
Pj := P[j*16 : (j+1)*16]
/* PPj = 2**(j-1)*L xor Pj */
xorBlocks(PPj, Pj, LTable[j])
/* PPPj = AESenc(K; PPj) */
aesTransform(C[j*16:(j+1)*16], PPj, direction, bc)
}
/* MP =(xorSum PPPj) xor T */
MP := make([]byte, 16)
xorBlocks(MP, C[0:16], T)
for j := 1; j < m; j++ {
xorBlocks(MP, MP, C[j*16:(j+1)*16])
}
/* MC = AESenc(K; MP) */
MC := make([]byte, 16)
aesTransform(MC, MP, direction, bc)
/* M = MP xor MC */
M := make([]byte, 16)
xorBlocks(M, MP, MC)
CCCj := make([]byte, 16)
for j := 1; j < m; j++ {
multByTwo(M, M)
/* CCCj = 2**(j-1)*M xor PPPj */
xorBlocks(CCCj, C[j*16:(j+1)*16], M)
copy(C[j*16:(j+1)*16], CCCj)
}
/* CCC1 = (xorSum CCCj) xor T xor MC */
CCC1 := make([]byte, 16)
xorBlocks(CCC1, MC, T)
for j := 1; j < m; j++ {
xorBlocks(CCC1, CCC1, C[j*16:(j+1)*16])
}
copy(C[0:16], CCC1)
for j := 0; j < m; j++ {
/* CCj = AES-enc(K; CCCj) */
aesTransform(C[j*16:(j+1)*16], C[j*16:(j+1)*16], direction, bc)
/* Cj = 2**(j-1)*L xor CCj */
xorBlocks(C[j*16:(j+1)*16], C[j*16:(j+1)*16], LTable[j])
}
return C
}
// EMECipher provides EME-Encryption and -Decryption functions that are more
// convenient than calling Transform directly.
type EMECipher struct {
bc cipher.Block
}
// New returns a new EMECipher object. "bc" must have a block size of 16,
// or subsequent calls to Encrypt and Decrypt will panic.
func New(bc cipher.Block) *EMECipher {
return &EMECipher{
bc: bc,
}
}
// Encrypt is equivalent to calling Transform with direction=DirectionEncrypt.
func (e *EMECipher) Encrypt(tweak []byte, inputData []byte) []byte {
return Transform(e.bc, tweak, inputData, DirectionEncrypt)
}
// Decrypt is equivalent to calling Transform with direction=DirectionDecrypt.
func (e *EMECipher) Decrypt(tweak []byte, inputData []byte) []byte {
return Transform(e.bc, tweak, inputData, DirectionDecrypt)
}

Binary file not shown.

Before

Width:  |  Height:  |  Size: 9.4 KiB

View File

@ -1,97 +0,0 @@
// Package exitcodes contains all well-defined exit codes that gocryptfs
// can return.
package exitcodes
import (
"fmt"
"os"
)
const (
// Usage - usage error like wrong cli syntax, wrong number of parameters.
Usage = 1
// 2 is reserved because it is used by Go panic
// 3 is reserved because it was used by earlier gocryptfs version as a generic
// "mount" error.
// CipherDir means that the CIPHERDIR does not exist, is not empty, or is not
// a directory.
CipherDir = 6
// Init is an error on filesystem init
Init = 7
// LoadConf is an error while loading gocryptfs.conf
LoadConf = 8
// ReadPassword means something went wrong reading the password
ReadPassword = 9
// MountPoint error means that the mountpoint is invalid (not empty etc).
MountPoint = 10
// Other error - please inspect the message
Other = 11
// PasswordIncorrect - the password was incorrect when mounting or when
// changing the password.
PasswordIncorrect = 12
// ScryptParams means that scrypt was called with invalid parameters
ScryptParams = 13
// MasterKey means that something went wrong when parsing the "-masterkey"
// command line option
MasterKey = 14
// SigInt means we got SIGINT
SigInt = 15
// PanicLogNotEmpty means the panic log was not empty when we were unmounted
PanicLogNotEmpty = 16
// ForkChild means forking the worker child failed
ForkChild = 17
// OpenSSL means you tried to enable OpenSSL, but we were compiled without it.
OpenSSL = 18
// FuseNewServer - this exit code means that the call to fuse.NewServer failed.
// This usually means that there was a problem executing fusermount, or
// fusermount could not attach the mountpoint to the kernel.
FuseNewServer = 19
// CtlSock - the control socket file could not be created.
CtlSock = 20
// Downgraded to a warning in gocryptfs v1.4
//PanicLogCreate = 21
// PasswordEmpty - we received an empty password
PasswordEmpty = 22
// OpenConf - the was an error opening the gocryptfs.conf file for reading
OpenConf = 23
// WriteConf - could not write the gocryptfs.conf
WriteConf = 24
// Profiler - error occurred when trying to write cpu or memory profile or
// execution trace
Profiler = 25
// FsckErrors - the filesystem check found errors
FsckErrors = 26
// DeprecatedFS - this filesystem is deprecated
DeprecatedFS = 27
// skip 28
// ExcludeError - an error occurred while processing "-exclude"
ExcludeError = 29
// DevNull means that /dev/null could not be opened
DevNull = 30
)
// Err wraps an error with an associated numeric exit code
type Err struct {
error
code int
}
// NewErr returns an error containing "msg" and the exit code "code".
func NewErr(msg string, code int) Err {
return Err{
error: fmt.Errorf(msg),
code: code,
}
}
// Exit extracts the numeric exit code from "err" (if available) and exits the
// application.
func Exit(err error) {
err2, ok := err.(Err)
if !ok {
os.Exit(Other)
}
os.Exit(err2.code)
}

View File

@ -1,22 +0,0 @@
# Compiled Object files, Static and Dynamic libs (Shared Objects)
*.o
*.a
*.so
# Folders
_obj
_test
# Architecture specific extensions/prefixes
*.[568vq]
[568vq].out
*.cgo1.go
*.cgo2.c
_cgo_defun.c
_cgo_gotypes.go
_cgo_export.*
_testmain.go
*.exe

View File

@ -1,4 +0,0 @@
# Cf. http://docs.travis-ci.com/user/getting-started/
# Cf. http://docs.travis-ci.com/user/languages/go/
language: go

View File

@ -1,202 +0,0 @@
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
1. Definitions.
"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.
"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.
"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.
"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.
"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.
"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.
"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).
"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.
"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."
"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.
2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.
3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.
4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:
(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and
(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and
(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and
(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.
You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.
5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.
6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.
7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.
8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.
9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.
END OF TERMS AND CONDITIONS
APPENDIX: How to apply the Apache License to your work.
To apply the Apache License to your work, attach the following
boilerplate notice, with the fields enclosed by brackets "[]"
replaced with your own identifying information. (Don't include
the brackets!) The text should be enclosed in the appropriate
comment syntax for the file format. We also recommend that a
file or class name and description of purpose be included on the
same "printed page" as the copyright notice for easier
identification within third-party archives.
Copyright [yyyy] [name of copyright owner]
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

View File

@ -1,10 +0,0 @@
This repository contains Go packages related to cryptographic standards that are
not included in the Go standard library. These include:
* [SIV mode][siv], which provides deterministic encryption with
authentication.
* [CMAC][cmac], a message authentication system used by SIV mode.
[siv]: https://godoc.org/github.com/jacobsa/crypto/siv
[cmac]: https://godoc.org/github.com/jacobsa/crypto/cmac

View File

@ -1,23 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cmac
import "crypto/aes"
// The size of an AES-CMAC checksum, in bytes.
const Size = aes.BlockSize
const blockSize = Size

View File

@ -1,19 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package cmac implements the CMAC mode for message authentication, as defined
// by NIST Special Publication 800-38B. When a 16-byte key is used, this
// matches the AES-CMAC algorithm defined by RFC 4493.
package cmac

View File

@ -1,170 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cmac
import (
"crypto/aes"
"crypto/cipher"
"fmt"
"hash"
"unsafe"
"../common"
)
type cmacHash struct {
// An AES cipher configured with the original key.
ciph cipher.Block
// Generated sub-keys.
k1 []byte
k2 []byte
// Data that has been seen by Write but not yet incorporated into x, due to
// us not being sure if it is the final block or not.
//
// INVARIANT: len(data) <= blockSize
data []byte
// The current value of X, as defined in the AES-CMAC algorithm in RFC 4493.
// Initially this is a 128-bit zero, and it is updated with the current block
// when we're sure it's not the last one.
x []byte
}
func (h *cmacHash) Write(p []byte) (n int, err error) {
n = len(p)
// First step: consume enough data to expand h.data to a full block, if
// possible.
{
toConsume := blockSize - len(h.data)
if toConsume > len(p) {
toConsume = len(p)
}
h.data = append(h.data, p[:toConsume]...)
p = p[toConsume:]
}
// If there's no data left in p, it means h.data might not be a full block.
// Even if it is, we're not sure it's the final block, which we must treat
// specially. So we must stop here.
if len(p) == 0 {
return
}
// h.data is a full block and is not the last; process it.
h.writeBlocks(h.data)
h.data = h.data[:0]
// Consume any further full blocks in p that we're sure aren't the last. Note
// that we're sure that len(p) is greater than zero here.
blocksToProcess := (len(p) - 1) / blockSize
bytesToProcess := blocksToProcess * blockSize
h.writeBlocks(p[:bytesToProcess])
p = p[bytesToProcess:]
// Store the rest for later.
h.data = append(h.data, p...)
return
}
// Process block-aligned data that we're sure does not contain the final block.
//
// REQUIRES: len(p) % blockSize == 0
func (h *cmacHash) writeBlocks(p []byte) {
y := make([]byte, blockSize)
for off := 0; off < len(p); off += blockSize {
block := p[off : off+blockSize]
xorBlock(
unsafe.Pointer(&y[0]),
unsafe.Pointer(&h.x[0]),
unsafe.Pointer(&block[0]))
h.ciph.Encrypt(h.x, y)
}
return
}
func (h *cmacHash) Sum(b []byte) []byte {
dataLen := len(h.data)
// We should have at most one block left.
if dataLen > blockSize {
panic(fmt.Sprintf("Unexpected data: %x", h.data))
}
// Calculate M_last.
mLast := make([]byte, blockSize)
if dataLen == blockSize {
common.Xor(mLast, h.data, h.k1)
} else {
// TODO(jacobsa): Accept a destination buffer in common.PadBlock and
// simplify this code.
common.Xor(mLast, common.PadBlock(h.data), h.k2)
}
y := make([]byte, blockSize)
common.Xor(y, mLast, h.x)
result := make([]byte, blockSize)
h.ciph.Encrypt(result, y)
b = append(b, result...)
return b
}
func (h *cmacHash) Reset() {
h.data = h.data[:0]
h.x = make([]byte, blockSize)
}
func (h *cmacHash) Size() int {
return h.ciph.BlockSize()
}
func (h *cmacHash) BlockSize() int {
return h.ciph.BlockSize()
}
// New returns an AES-CMAC hash using the supplied key. The key must be 16, 24,
// or 32 bytes long.
func New(key []byte) (hash.Hash, error) {
switch len(key) {
case 16, 24, 32:
default:
return nil, fmt.Errorf("AES-CMAC requires a 16-, 24-, or 32-byte key.")
}
// Create a cipher.
ciph, err := aes.NewCipher(key)
if err != nil {
return nil, fmt.Errorf("aes.NewCipher: %v", err)
}
// Set up the hash object.
h := &cmacHash{ciph: ciph}
h.k1, h.k2 = generateSubkeys(ciph)
h.Reset()
return h, nil
}

View File

@ -1,47 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build 386 arm,!arm64 mips mipsle
package cmac
import (
"log"
"unsafe"
)
// XOR the blockSize bytes starting at a and b, writing the result over dst.
func xorBlock(
dstPtr unsafe.Pointer,
aPtr unsafe.Pointer,
bPtr unsafe.Pointer) {
// Check assumptions. (These are compile-time constants, so this should
// compile out.)
const wordSize = unsafe.Sizeof(uintptr(0))
if blockSize != 4*wordSize {
log.Panicf("%d %d", blockSize, wordSize)
}
// Convert.
a := (*[4]uintptr)(aPtr)
b := (*[4]uintptr)(bPtr)
dst := (*[4]uintptr)(dstPtr)
// Compute.
dst[0] = a[0] ^ b[0]
dst[1] = a[1] ^ b[1]
dst[2] = a[2] ^ b[2]
dst[3] = a[3] ^ b[3]
}

View File

@ -1,55 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build amd64 arm64 ppc64 ppc64le s390x mips64 mips64le
// This code assumes that it's safe to perform unaligned word-sized loads. This is safe on:
// - arm64 per http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0024a/ch05s01s02.html
// - Section "5.5.8 Alignment Interrupt" of PowerPC Operating Environment Architecture Book III Version 2.02
// (the first PowerPC ISA version to include 64-bit), available from
// http://www.ibm.com/developerworks/systems/library/es-archguide-v2.html does not permit fixed-point loads
// or stores to generate exceptions on unaligned access
// - IBM mainframe's have allowed unaligned accesses since the System/370 arrived in 1970
// - On mips unaligned accesses are fixed up by the kernel per https://www.linux-mips.org/wiki/Alignment
// so performance might be quite bad but it will work.
package cmac
import (
"log"
"unsafe"
)
// XOR the blockSize bytes starting at a and b, writing the result over dst.
func xorBlock(
dstPtr unsafe.Pointer,
aPtr unsafe.Pointer,
bPtr unsafe.Pointer) {
// Check assumptions. (These are compile-time constants, so this should
// compile out.)
const wordSize = unsafe.Sizeof(uintptr(0))
if blockSize != 2*wordSize {
log.Panicf("%d %d", blockSize, wordSize)
}
// Convert.
a := (*[2]uintptr)(aPtr)
b := (*[2]uintptr)(bPtr)
dst := (*[2]uintptr)(dstPtr)
// Compute.
dst[0] = a[0] ^ b[0]
dst[1] = a[1] ^ b[1]
}

View File

@ -1,65 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cmac
import (
"bytes"
"crypto/cipher"
"../common"
)
var subkeyZero []byte
var subkeyRb []byte
func init() {
subkeyZero = bytes.Repeat([]byte{0x00}, blockSize)
subkeyRb = append(bytes.Repeat([]byte{0x00}, blockSize-1), 0x87)
}
// Given the supplied cipher, whose block size must be 16 bytes, return two
// subkeys that can be used in MAC generation. See section 5.3 of NIST SP
// 800-38B. Note that the other NIST-approved block size of 8 bytes is not
// supported by this function.
func generateSubkeys(ciph cipher.Block) (k1 []byte, k2 []byte) {
if ciph.BlockSize() != blockSize {
panic("generateSubkeys requires a cipher with a block size of 16 bytes.")
}
// Step 1
l := make([]byte, blockSize)
ciph.Encrypt(l, subkeyZero)
// Step 2: Derive the first subkey.
if common.Msb(l) == 0 {
// TODO(jacobsa): Accept a destination buffer in ShiftLeft and then hoist
// the allocation in the else branch below.
k1 = common.ShiftLeft(l)
} else {
k1 = make([]byte, blockSize)
common.Xor(k1, common.ShiftLeft(l), subkeyRb)
}
// Step 3: Derive the second subkey.
if common.Msb(k1) == 0 {
k2 = common.ShiftLeft(k1)
} else {
k2 = make([]byte, blockSize)
common.Xor(k2, common.ShiftLeft(k1), subkeyRb)
}
return
}

View File

@ -1,18 +0,0 @@
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package common contains common implementation details of other packages, and
// should not be used directly.
package common