// Opens a file to read the configuration elements from.
// fn: Filename to open.
// password: Password to encrypt and decrypt secure content.
// Has to be either, 16, 24, or 32 in length.
func Open(fn, password string) (*Configurator, error) {
pl := len(password)
switch pl {
default:
return nil, aes.KeySizeError(pl)
case 16, 24, 32:
break
}
f, err := os.Open(fn)
if err != nil {
return nil, err
}
defer f.Close()
scanner := bufio.NewScanner(f)
lines := make(map[string]string)
for i := 1; scanner.Scan(); i++ {
str := strings.Split(scanner.Text(), "=")
lines[str[0]] = str[1]
}
block, err := aes.NewCipher([]byte(password))
if err != nil {
return nil, err
}
return &Configurator{
filename: fn,
lines: lines,
cipherBlock: block,
decrypted: make(map[string]string),
}, nil
}
// Read checks the validity of a file and attempts to decrypt it.
func (m *MutableFile) Read(p []byte) (n int, err error) {
// delegate VK checking to Verify()
if m.Cap.rk == nil {
return 0, CapabilityError
}
ok, err := m.Verify()
if err != nil {
return 0, err
}
if !ok {
return 0, rsa.ErrVerification
}
// TODO don't repeat this file read
filePath := path.Join(m.storageDir, m.filename)
rawFile, err := ioutil.ReadFile(filePath)
if err != nil {
return 0, err
}
sigSize := AsymmetricKeySize / 8
sigOffset := len(rawFile) - sigSize
// for generating EK from RK
fileSalt := rawFile[:SaltSize]
ek := truncHash(TagEKFromSaltRK, append(m.Cap.rk, fileSalt...), SymmetricKeySize)
if ek == nil || len(ek) != SymmetricKeySize {
return 0, aes.KeySizeError(len(ek))
}
block, err := aes.NewCipher(ek)
if err != nil {
return 0, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return 0, err
}
// skip salt, get nonce, stop before ciphertext
nonce := rawFile[SaltSize : SaltSize+gcm.NonceSize()]
// skip salt and nonce, get ciphertext|tag, stop before sig
ciphertext := rawFile[SaltSize+gcm.NonceSize() : sigOffset]
decryptBytes, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return 0, nil
}
if cap(p) < len(decryptBytes) {
return copy(p, decryptBytes[:cap(p)]), io.ErrShortBuffer
} else {
return copy(p, decryptBytes), io.EOF
}
}
// Write writes a file. Format is
// {
// fileSalt [16]byte
// gcmNonce [12]byte
// ciphertext [len(contents)]byte
// gcmTag [16]byte
// signature [256]byte
// }
func (m *MutableFile) Write(data []byte) (n int, err error) {
// TODO check capability derivation chains
if m.Cap.sk == nil || m.Cap.rk == nil || m.salt == nil {
return 0, CapabilityError
}
ek := truncHash(TagEKFromSaltRK, append(m.Cap.rk, m.salt...), SymmetricKeySize)
if ek == nil || len(ek) != SymmetricKeySize {
return 0, aes.KeySizeError(len(ek))
}
block, err := aes.NewCipher(ek)
if err != nil {
return 0, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return 0, err
}
buf := make([]byte, len(m.salt))
copy(buf, m.salt)
nonce := make([]byte, gcm.NonceSize())
n, err = rand.Read(nonce)
if n != gcm.NonceSize() || err != nil {
panic("rand.Read failed!1!!")
}
buf = append(buf, nonce...)
buf = gcm.Seal(buf, nonce, data, nil)
// remember that this is hashing all of salt|nonce|ciphertext|tag
hashed := sha256.Sum256(buf)
sig, err := rsa.SignPKCS1v15(rand.Reader, m.Cap.sk, crypto.SHA256, hashed[:])
if err != nil {
return 0, err
}
out, err := os.Create(path.Join(m.storageDir, m.filename))
if err != nil {
return 0, err
}
defer out.Close()
bufN, err := out.Write(buf)
if err != nil {
return 0, err
}
sigN, err := out.Write(sig)
if err != nil {
return 0, err
}
return bufN + sigN, nil
}
func TestCreateEndpoint(t *testing.T) {
useMockFuncs()
defer useStdFuncs()
mockCtrl := gomock.NewController(t)
defer mockCtrl.Finish()
mckEndHandler := NewMockHandler(mockCtrl)
Convey("Should allocate update endpoints", t, func() {
app := NewApplication()
app.endpointTemplate = testEndpointTemplate
Convey("Should not encrypt endpoints without a key", func() {
app.SetTokenKey("")
app.SetEndpointHandler(mckEndHandler)
mckEndHandler.EXPECT().URL().Return("https://example.com")
endpoint, err := app.CreateEndpoint("123")
So(err, ShouldBeNil)
So(endpoint, ShouldEqual, "https://example.com/123")
})
Convey("Should encrypt endpoints with a key", func() {
app.SetTokenKey("HVozKz_n-DPopP5W877DpRKQOW_dylVf")
app.SetEndpointHandler(mckEndHandler)
mckEndHandler.EXPECT().URL().Return("https://example.com")
endpoint, err := app.CreateEndpoint("456")
So(err, ShouldBeNil)
So(endpoint, ShouldEqual,
"https://example.com/AAAAAAAAAAAAAAAAAAAAAGMKig==")
})
Convey("Should reject invalid keys", func() {
app.SetTokenKey("lLyhlLk8qus1ky4ER8yjN5o=")
app.SetEndpointHandler(mckEndHandler)
_, err := app.CreateEndpoint("123")
So(err, ShouldEqual, aes.KeySizeError(17))
})
Convey("Should return a relative URL without an update handler", func() {
app.SetTokenKey("O03rpLsdafhIhJEjEJt-CgVHyqHI650oy0pZZvplKDc=")
endpoint, err := app.CreateEndpoint("789")
So(err, ShouldBeNil)
So(endpoint, ShouldEqual, "/AAAAAAAAAAAAAAAAAAAAAPfdsA==")
})
})
}
func Test_Decode(t *testing.T) {
var (
decrypted, expected []byte
err error
)
key := []byte{0xf8, 0x59, 0x4, 0x72, 0x1c, 0xa, 0xc, 0x85, 0x5b, 0x7a,
0x61, 0x26, 0xa5, 0x5a, 0xe2, 0x3b}
encrypted := "6MgxfnBKjWtSNm6Q9WunFbj2hcjmeDudKuWUAeU="
if decrypted, err = Decode(key, encrypted); err != nil {
t.Errorf("Error decoding value: %s", err)
}
expected = []byte("Hello, world!")
if !bytes.Equal(decrypted, expected) {
t.Errorf("Unexpected result decoding with key: want %#v; got %#v",
expected, decrypted)
}
if _, err = Decode(key[:14], "6MgxfnBKjWtSNm6Q9WunFbj2hcjmeDudKuWUAeU="); err != aes.KeySizeError(14) {
t.Errorf("Invalid key size: want aes.KeySizeError(14); got %s", err)
}
if _, err = Decode(key, "!@#$%^&*()-+[]{}"); err != base64.CorruptInputError(0) {
t.Errorf("Invalid Base64: want base64.CorruptInputError(0); got %s", err)
}
if _, err = Decode(key, encrypted[:8]); err != ValueSizeError(6) {
t.Errorf("Encrypted value too short: want ValueSizeError(6); got %s", err)
}
if decrypted, err = Decode(nil, encrypted); err != nil {
t.Errorf("Error decoding without key: %s", err)
}
expected = []byte(encrypted)
if !bytes.Equal(decrypted, expected) {
t.Errorf("Unexpected result decoding without key: want %#v; got %#v",
expected, decrypted)
}
if decrypted, err = Decode(key, ""); err != nil {
t.Errorf("Error decoding empty string: %s", err)
}
if len(decrypted) != 0 {
t.Errorf("Unexpected result decoding empty string: got %#v", decrypted)
}
// Empty payload with valid IV.
if decrypted, err = Decode(key, "dEmnrPZHgiOgttx5lhkx4w=="); err != nil {
t.Errorf("Error decoding empty payload: %s", err)
}
if len(decrypted) != 0 {
t.Errorf("Unexpected result decoding empty payload: got %#v", decrypted)
}
}
// Decrypt decrypts data using 256-bit AES-GCM. This both hides the content of
// the data and provides a check that it hasn't been altered. Expects input
// form nonce|ciphertext|tag where '|' indicates concatenation.
func Decrypt(ciphertext, key []byte) (plaintext []byte, err error) {
if len(key) != aesKeySize {
return nil, aes.KeySizeError(len(key))
}
aes, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(aes)
if err != nil {
return nil, err
}
return gcm.Open(nil, ciphertext[:gcm.NonceSize()],
ciphertext[gcm.NonceSize():], nil)
}
// Encrypt encrypts data using 256-bit AES-GCM. This both hides the content of
// the data and provides a check that it hasn't been altered. Output takes the
// form nonce|ciphertext|tag where '|' indicates concatenation.
func Encrypt(plaintext, key []byte) (ciphertext []byte, err error) {
if len(key) != aesKeySize {
return nil, aes.KeySizeError(len(key))
}
aes, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(aes)
if err != nil {
return nil, err
}
nonce, err := generateBytes(gcm.NonceSize())
if err != nil {
return nil, err
}
return gcm.Seal(nonce, nonce, plaintext, nil), nil
}
// NewAes256Gcm creates new Aes256Gcm with key
func NewAes256Gcm(key []byte) (*Aes256Gcm, error) {
if len(key) != KeySize {
return nil, aes.KeySizeError(len(key))
}
return &Aes256Gcm{key: key}, nil
}