package cluster import ( "crypto/aes" "crypto/cipher" "crypto/rand" "crypto/sha1" "crypto/sha256" "encoding/base64" "encoding/hex" "fmt" "io" "strings" "github.com/rancher/k3s/pkg/token" "golang.org/x/crypto/pbkdf2" ) // storageKey returns the etcd key for storing bootstrap data for a given passphrase. // The key is derived from the sha256 hash of the passphrase. func storageKey(passphrase string) string { return "/bootstrap/" + keyHash(passphrase) } // keyHash returns the first 12 characters of the sha256 sum of the passphrase. func keyHash(passphrase string) string { d := sha256.New() d.Write([]byte(passphrase)) return hex.EncodeToString(d.Sum(nil)[:])[:12] } // encrypt encrypts a byte slice using aes+gcm with a pbkdf2 key derived from the passphrase and a random salt. // It returns a byte slice containing the salt and base64-encoded ciphertext. func encrypt(passphrase string, plaintext []byte) ([]byte, error) { salt, err := token.Random(8) if err != nil { return nil, err } clearKey := pbkdf2.Key([]byte(passphrase), []byte(salt), 4096, 32, sha1.New) key, err := aes.NewCipher(clearKey) if err != nil { return nil, err } gcm, err := cipher.NewGCM(key) if err != nil { return nil, err } nonce := make([]byte, gcm.NonceSize()) _, err = io.ReadFull(rand.Reader, nonce) if err != nil { return nil, err } sealed := gcm.Seal(nonce, nonce, plaintext, nil) return []byte(salt + ":" + base64.StdEncoding.EncodeToString(sealed)), nil } // decrypt attempts to decrypt the byte slice using the supplied passphrase. // The input byte slice should be the ciphertext output from the encrypt function. func decrypt(passphrase string, ciphertext []byte) ([]byte, error) { parts := strings.SplitN(string(ciphertext), ":", 2) if len(parts) != 2 { return nil, fmt.Errorf("invalid cipher text, not : delimited") } clearKey := pbkdf2.Key([]byte(passphrase), []byte(parts[0]), 4096, 32, sha1.New) key, err := aes.NewCipher(clearKey) if err != nil { return nil, err } gcm, err := cipher.NewGCM(key) if err != nil { return nil, err } data, err := base64.StdEncoding.DecodeString(parts[1]) if err != nil { return nil, err } return gcm.Open(nil, data[:gcm.NonceSize()], data[gcm.NonceSize():], nil) }