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crypto.go nitpicks

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This commit is contained in:
Florian Weingarten 2015-04-29 22:28:34 -04:00
parent a906b9febe
commit c500b94216
6 changed files with 55 additions and 86 deletions
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82
crypto/crypto.go
View File

@ -14,13 +14,13 @@ import (
)
const (
aesKeySize = 32 // for AES256
aesKeySize = 32 // for AES-256
macKeySizeK = 16 // for AES-128
macKeySizeR = 16 // for Poly1305
macKeySize = macKeySizeK + macKeySizeR // for Poly1305-AES128
ivSize = aes.BlockSize
macSize = poly1305.TagSize // Poly1305 size is 16 byte
macSize = poly1305.TagSize
Extension = ivSize + macSize
)
@ -45,8 +45,8 @@ type Key struct {
type EncryptionKey [32]byte
type SigningKey struct {
K [16]byte `json:"k"` // for AES128
R [16]byte `json:"r"` // for Poly1305
K [16]byte // for AES-128
R [16]byte // for Poly1305
masked bool // remember if the signing key has already been masked
}
@ -71,27 +71,9 @@ var poly1305KeyMask = [16]byte{
0x0f, // 15: top four bits zero
}
// key is a [32]byte, in the form k||r
func poly1305Sign(msg []byte, nonce []byte, key *SigningKey) []byte {
// prepare key for low-level poly1305.Sum(): r||n
var k [32]byte
k := poly1305PrepareKey(nonce, key)
// make sure key is masked
if !key.masked {
maskKey(key)
}
// fill in nonce, encrypted with AES and key[:16]
cipher, err := aes.NewCipher(key.K[:])
if err != nil {
panic(err)
}
cipher.Encrypt(k[16:], nonce[:])
// copy r
copy(k[:16], key.R[:])
// save mac in out
var out [16]byte
poly1305.Sum(&out, msg, &k)
@ -100,9 +82,10 @@ func poly1305Sign(msg []byte, nonce []byte, key *SigningKey) []byte {
// mask poly1305 key
func maskKey(k *SigningKey) {
if k == nil {
if k == nil || k.masked {
return
}
for i := 0; i < poly1305.TagSize; i++ {
k.R[i] = k.R[i] & poly1305KeyMask[i]
}
@ -117,36 +100,36 @@ func macKeyFromSlice(mk *SigningKey, data []byte) {
maskKey(mk)
}
// key: k||r
func poly1305Verify(msg []byte, nonce []byte, key *SigningKey, mac []byte) bool {
// prepare key for low-level poly1305.Sum(): r||n
// prepare key for low-level poly1305.Sum(): r||n
func poly1305PrepareKey(nonce []byte, key *SigningKey) [32]byte {
var k [32]byte
// make sure key is masked
if !key.masked {
maskKey(key)
}
maskKey(key)
// fill in nonce, encrypted with AES and key[:16]
cipher, err := aes.NewCipher(key.K[:])
if err != nil {
panic(err)
}
cipher.Encrypt(k[16:], nonce[:])
// copy r
copy(k[:16], key.R[:])
// copy mac to array
return k
}
func poly1305Verify(msg []byte, nonce []byte, key *SigningKey, mac []byte) bool {
k := poly1305PrepareKey(nonce, key)
var m [16]byte
copy(m[:], mac)
return poly1305.Verify(&m, msg, &k)
}
// NewKey returns new encryption and signing keys.
func NewKey() (k *Key) {
k = &Key{}
// NewRandomKey returns new encryption and signing keys.
func NewRandomKey() *Key {
k := &Key{}
n, err := rand.Read(k.Encrypt[:])
if n != aesKeySize || err != nil {
panic("unable to read enough random bytes for encryption key")
@ -161,9 +144,8 @@ func NewKey() (k *Key) {
if n != macKeySizeR || err != nil {
panic("unable to read enough random bytes for mac signing key")
}
// mask r
maskKey(&k.Sign)
maskKey(&k.Sign)
return k
}
@ -220,7 +202,7 @@ var ErrInvalidCiphertext = errors.New("invalid ciphertext, same slice used for p
// MAC. Encrypt returns the new ciphertext slice, which is extended when
// necessary. ciphertext and plaintext may not point to (exactly) the same
// slice or non-intersecting slices.
func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
func Encrypt(ks *Key, ciphertext []byte, plaintext []byte) ([]byte, error) {
ciphertext = ciphertext[:cap(ciphertext)]
// test for same slice, if possible
@ -245,11 +227,11 @@ func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
e.XORKeyStream(ciphertext[ivSize:], plaintext)
copy(ciphertext, iv[:])
// truncate to only conver iv and actual ciphertext
// truncate to only cover iv and actual ciphertext
ciphertext = ciphertext[:ivSize+len(plaintext)]
mac := poly1305Sign(ciphertext[ivSize:], ciphertext[:ivSize], &ks.Sign)
// append the mac tag
ciphertext = append(ciphertext, mac...)
return ciphertext, nil
@ -258,28 +240,28 @@ func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
// Decrypt verifies and decrypts the ciphertext. Ciphertext must be in the form
// IV || Ciphertext || MAC. plaintext and ciphertext may point to (exactly) the
// same slice.
func Decrypt(ks *Key, plaintext, ciphertext []byte) ([]byte, error) {
func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error) {
// check for plausible length
if len(ciphertext) < ivSize+macSize {
if len(ciphertextWithMac) < ivSize+macSize {
panic("trying to decrypt invalid data: ciphertext too small")
}
if cap(plaintext) < len(ciphertext) {
if cap(plaintext) < len(ciphertextWithMac) {
// extend plaintext
plaintext = append(plaintext, make([]byte, len(ciphertext)-cap(plaintext))...)
plaintext = append(plaintext, make([]byte, len(ciphertextWithMac)-cap(plaintext))...)
}
// extract mac
l := len(ciphertext) - macSize
ciphertext, mac := ciphertext[:l], ciphertext[l:]
l := len(ciphertextWithMac) - macSize
ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:]
// verify mac
if !poly1305Verify(ciphertext[ivSize:], ciphertext[:ivSize], &ks.Sign, mac) {
if !poly1305Verify(ciphertextWithIV[ivSize:], ciphertextWithIV[:ivSize], &ks.Sign, mac) {
return nil, ErrUnauthenticated
}
// extract iv
iv, ciphertext := ciphertext[:ivSize], ciphertext[ivSize:]
iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:]
// decrypt data
c, err := aes.NewCipher(ks.Encrypt[:])

28
crypto/crypto_int_test.go
View File

@ -61,15 +61,16 @@ func TestPoly1305(t *testing.T) {
}
var testValues = []struct {
ekey EncryptionKey
skey SigningKey
ciphertext []byte
plaintext []byte
shouldPanic bool
ekey EncryptionKey
skey SigningKey
ciphertext []byte
plaintext []byte
}{
{
ekey: EncryptionKey([...]byte{0x30, 0x3e, 0x86, 0x87, 0xb1, 0xd7, 0xdb, 0x18, 0x42, 0x1b, 0xdc, 0x6b, 0xb8, 0x58, 0x8c, 0xca,
0xda, 0xc4, 0xd5, 0x9e, 0xe8, 0x7b, 0x8f, 0xf7, 0x0c, 0x44, 0xe6, 0x35, 0x79, 0x0c, 0xaf, 0xef}),
ekey: EncryptionKey([...]byte{
0x30, 0x3e, 0x86, 0x87, 0xb1, 0xd7, 0xdb, 0x18, 0x42, 0x1b, 0xdc, 0x6b, 0xb8, 0x58, 0x8c, 0xca,
0xda, 0xc4, 0xd5, 0x9e, 0xe8, 0x7b, 0x8f, 0xf7, 0x0c, 0x44, 0xe6, 0x35, 0x79, 0x0c, 0xaf, 0xef,
}),
skey: SigningKey{
K: [...]byte{0xef, 0x4d, 0x88, 0x24, 0xcb, 0x80, 0xb2, 0xbc, 0xc5, 0xfb, 0xff, 0x8a, 0x9b, 0x12, 0xa4, 0x2c},
R: [...]byte{0xcc, 0x8d, 0x4b, 0x94, 0x8e, 0xe0, 0xeb, 0xfe, 0x1d, 0x41, 0x5d, 0xe9, 0x21, 0xd1, 0x03, 0x53},
@ -84,19 +85,6 @@ func decodeHex(s string) []byte {
return d
}
// returns true if function called panic
func shouldPanic(f func()) (didPanic bool) {
defer func() {
if r := recover(); r != nil {
didPanic = true
}
}()
f()
return false
}
func TestCrypto(t *testing.T) {
msg := make([]byte, 0, 8*1024*1024) // use 8MiB for now
for _, tv := range testValues {

26
crypto/crypto_test.go
View File

@ -17,7 +17,7 @@ import (
var testLargeCrypto = flag.Bool("test.largecrypto", false, "also test crypto functions with large payloads")
func TestEncryptDecrypt(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
tests := []int{5, 23, 2<<18 + 23, 1 << 20}
if *testLargeCrypto {
@ -48,7 +48,7 @@ func TestEncryptDecrypt(t *testing.T) {
}
func TestSmallBuffer(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
size := 600
data := make([]byte, size)
@ -73,7 +73,7 @@ func TestSmallBuffer(t *testing.T) {
}
func TestSameBuffer(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
size := 600
data := make([]byte, size)
@ -96,7 +96,7 @@ func TestSameBuffer(t *testing.T) {
}
func TestCornerCases(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
// nil plaintext should encrypt to the empty string
// nil ciphertext should allocate a new slice for the ciphertext
@ -122,7 +122,7 @@ func TestLargeEncrypt(t *testing.T) {
t.SkipNow()
}
k := crypto.NewKey()
k := crypto.NewRandomKey()
for _, size := range []int{chunker.MaxSize, chunker.MaxSize + 1, chunker.MaxSize + 1<<20} {
data := make([]byte, size)
@ -146,7 +146,7 @@ func BenchmarkEncryptWriter(b *testing.B) {
size := 8 << 20 // 8MiB
rd := RandomReader(23, size)
k := crypto.NewKey()
k := crypto.NewRandomKey()
b.ResetTimer()
b.SetBytes(int64(size))
@ -166,7 +166,7 @@ func BenchmarkEncrypt(b *testing.B) {
size := 8 << 20 // 8MiB
data := make([]byte, size)
k := crypto.NewKey()
k := crypto.NewRandomKey()
buf := make([]byte, len(data)+crypto.Extension)
b.ResetTimer()
@ -181,7 +181,7 @@ func BenchmarkEncrypt(b *testing.B) {
func BenchmarkDecryptReader(b *testing.B) {
size := 8 << 20 // 8MiB
buf := Random(23, size)
k := crypto.NewKey()
k := crypto.NewRandomKey()
ciphertext := make([]byte, len(buf)+crypto.Extension)
_, err := crypto.Encrypt(k, ciphertext, buf)
@ -203,7 +203,7 @@ func BenchmarkDecryptReader(b *testing.B) {
}
func BenchmarkEncryptDecryptReader(b *testing.B) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
size := 8 << 20 // 8MiB
rd := RandomReader(23, size)
@ -234,7 +234,7 @@ func BenchmarkDecrypt(b *testing.B) {
size := 8 << 20 // 8MiB
data := make([]byte, size)
k := crypto.NewKey()
k := crypto.NewRandomKey()
ciphertext := restic.GetChunkBuf("BenchmarkDecrypt")
defer restic.FreeChunkBuf("BenchmarkDecrypt", ciphertext)
@ -254,7 +254,7 @@ func BenchmarkDecrypt(b *testing.B) {
}
func TestEncryptStreamWriter(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
tests := []int{5, 23, 2<<18 + 23, 1 << 20}
if *testLargeCrypto {
@ -288,7 +288,7 @@ func TestEncryptStreamWriter(t *testing.T) {
}
func TestDecryptStreamReader(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
tests := []int{5, 23, 2<<18 + 23, 1 << 20}
if *testLargeCrypto {
@ -322,7 +322,7 @@ func TestDecryptStreamReader(t *testing.T) {
}
func TestEncryptWriter(t *testing.T) {
k := crypto.NewKey()
k := crypto.NewRandomKey()
tests := []int{5, 23, 2<<18 + 23, 1 << 20}
if *testLargeCrypto {

1
crypto/reader.go
View File

@ -77,7 +77,6 @@ func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
ciphertext := buf.Bytes()
// decrypt
ciphertext, err = Decrypt(ks, ciphertext, ciphertext)
if err != nil {
return nil, err

2
pack/pack_test.go
View File

@ -37,7 +37,7 @@ func TestCreatePack(t *testing.T) {
file := bytes.NewBuffer(nil)
// create random keys
k := crypto.NewKey()
k := crypto.NewRandomKey()
// pack blobs
p := pack.NewPacker(k, file)

2
server/key.go
View File

@ -176,7 +176,7 @@ func AddKey(s *Server, password string, template *Key) (*Key, error) {
if template == nil {
// generate new random master keys
newkey.master = crypto.NewKey()
newkey.master = crypto.NewRandomKey()
// generate random polynomial for cdc
p, err := chunker.RandomPolynomial()
if err != nil {