rclone/fs/config/obscure.go
Nick Craig-Wood 11da2a6c9b Break the fs package up into smaller parts.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.
2018-01-15 17:51:14 +00:00

96 lines
2.4 KiB
Go

// Obscure and Reveal config values
package config
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/base64"
"io"
"log"
"github.com/pkg/errors"
)
// crypt internals
var (
cryptKey = []byte{
0x9c, 0x93, 0x5b, 0x48, 0x73, 0x0a, 0x55, 0x4d,
0x6b, 0xfd, 0x7c, 0x63, 0xc8, 0x86, 0xa9, 0x2b,
0xd3, 0x90, 0x19, 0x8e, 0xb8, 0x12, 0x8a, 0xfb,
0xf4, 0xde, 0x16, 0x2b, 0x8b, 0x95, 0xf6, 0x38,
}
cryptBlock cipher.Block
cryptRand = rand.Reader
)
// crypt transforms in to out using iv under AES-CTR.
//
// in and out may be the same buffer.
//
// Note encryption and decryption are the same operation
func crypt(out, in, iv []byte) error {
if cryptBlock == nil {
var err error
cryptBlock, err = aes.NewCipher(cryptKey)
if err != nil {
return err
}
}
stream := cipher.NewCTR(cryptBlock, iv)
stream.XORKeyStream(out, in)
return nil
}
// Obscure a value
//
// This is done by encrypting with AES-CTR
func Obscure(x string) (string, error) {
plaintext := []byte(x)
ciphertext := make([]byte, aes.BlockSize+len(plaintext))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(cryptRand, iv); err != nil {
return "", errors.Wrap(err, "failed to read iv")
}
if err := crypt(ciphertext[aes.BlockSize:], plaintext, iv); err != nil {
return "", errors.Wrap(err, "encrypt failed")
}
return base64.RawURLEncoding.EncodeToString(ciphertext), nil
}
// MustObscure obscures a value, exiting with a fatal error if it failed
func MustObscure(x string) string {
out, err := Obscure(x)
if err != nil {
log.Fatalf("Obscure failed: %v", err)
}
return out
}
// Reveal an obscured value
func Reveal(x string) (string, error) {
ciphertext, err := base64.RawURLEncoding.DecodeString(x)
if err != nil {
return "", errors.Wrap(err, "base64 decode failed when revealing password - is it obscured?")
}
if len(ciphertext) < aes.BlockSize {
return "", errors.New("input too short when revealing password - is it obscured?")
}
buf := ciphertext[aes.BlockSize:]
iv := ciphertext[:aes.BlockSize]
if err := crypt(buf, buf, iv); err != nil {
return "", errors.Wrap(err, "decrypt failed when revealing password - is it obscured?")
}
return string(buf), nil
}
// MustReveal reveals an obscured value, exiting with a fatal error if it failed
func MustReveal(x string) string {
out, err := Reveal(x)
if err != nil {
log.Fatalf("Reveal failed: %v", err)
}
return out
}