1
mirror of https://github.com/rclone/rclone synced 2024-12-24 15:43:45 +01:00
rclone/fs/config/obscure/obscure.go
2018-01-18 20:19:55 +00:00

95 lines
2.4 KiB
Go

// Package obscure contains the Obscure and Reveal commands
package obscure
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
}