grafana/pkg/util/encryption.go

79 lines
2.0 KiB
Go

package util
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"errors"
"golang.org/x/crypto/pbkdf2"
"io"
)
const saltLength = 8
// Decrypt decrypts a payload with a given secret.
func Decrypt(payload []byte, secret string) ([]byte, error) {
salt := payload[:saltLength]
key, err := encryptionKeyToBytes(secret, string(salt))
if err != nil {
return nil, err
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
if len(payload) < aes.BlockSize {
return nil, errors.New("payload too short")
}
iv := payload[saltLength : saltLength+aes.BlockSize]
payload = payload[saltLength+aes.BlockSize:]
payloadDst := make([]byte, len(payload))
stream := cipher.NewCFBDecrypter(block, iv)
// XORKeyStream can work in-place if the two arguments are the same.
stream.XORKeyStream(payloadDst, payload)
return payloadDst, nil
}
// Encrypt encrypts a payload with a given secret.
func Encrypt(payload []byte, secret string) ([]byte, error) {
salt, err := GetRandomString(saltLength)
if err != nil {
return nil, err
}
key, err := encryptionKeyToBytes(secret, salt)
if err != nil {
return nil, err
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
ciphertext := make([]byte, saltLength+aes.BlockSize+len(payload))
copy(ciphertext[:saltLength], []byte(salt))
iv := ciphertext[saltLength : saltLength+aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
stream := cipher.NewCFBEncrypter(block, iv)
stream.XORKeyStream(ciphertext[saltLength+aes.BlockSize:], payload)
return ciphertext, nil
}
// Key needs to be 32bytes
func encryptionKeyToBytes(secret, salt string) ([]byte, error) {
return pbkdf2.Key([]byte(secret), []byte(salt), 10000, 32, sha256.New), nil
}