From 069704832aaefc1b861839d93da63a7c7b803750 Mon Sep 17 00:00:00 2001
From: Jarek Kowalski <jaak@jkowalski.net>
Date: Tue, 27 Sep 2016 22:33:44 -0700
Subject: [PATCH] added SCrypt

---
 vault/creds.go  | 30 +++++++++++++++++++++++-------
 vault/format.go |  1 +
 vault/vault.go  | 15 +++++++++++++--
 3 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/vault/creds.go b/vault/creds.go
index 5437fc417..55f873aee 100644
--- a/vault/creds.go
+++ b/vault/creds.go
@@ -4,32 +4,39 @@
 	"crypto/sha256"
 	"fmt"
 
+	"golang.org/x/crypto/scrypt"
+
 	"golang.org/x/crypto/pbkdf2"
 )
 
 const (
 	passwordBasedKeySize = 32
 
-	pbkdf2Rounds = 10000
-
 	// MinPasswordLength is the minimum allowed length of a password in charcters.
 	MinPasswordLength = 12
 
 	// MinMasterKeyLength is the minimum allowed length of a master key, in bytes.
 	MinMasterKeyLength = 16
+
+	defaultKeyAlgorithm = "scrypt-65536-8-1"
 )
 
+var SupportedKeyAlgorithms = []string{
+	"scrypt-65536-8-1",
+	"pbkdf2-sha256-100000",
+}
+
 // Credentials encapsulates credentials used to encrypt a Vault.
 type Credentials interface {
-	getMasterKey(salt []byte) []byte
+	getMasterKey(f *Format) ([]byte, error)
 }
 
 type masterKeyCredentials struct {
 	key []byte
 }
 
-func (mkc *masterKeyCredentials) getMasterKey(salt []byte) []byte {
-	return mkc.key
+func (mkc *masterKeyCredentials) getMasterKey(f *Format) ([]byte, error) {
+	return mkc.key, nil
 }
 
 // MasterKey returns master key-based Credentials with the specified key.
@@ -45,8 +52,17 @@ type passwordCredentials struct {
 	password string
 }
 
-func (pc *passwordCredentials) getMasterKey(salt []byte) []byte {
-	return pbkdf2.Key([]byte(pc.password), salt, pbkdf2Rounds, passwordBasedKeySize, sha256.New)
+func (pc *passwordCredentials) getMasterKey(f *Format) ([]byte, error) {
+	switch f.KeyAlgo {
+	case "pbkdf2-sha256-100000":
+		return pbkdf2.Key([]byte(pc.password), f.UniqueID, 100000, passwordBasedKeySize, sha256.New), nil
+
+	case "scrypt-65536-8-1":
+		return scrypt.Key([]byte(pc.password), f.UniqueID, 65536, 8, 1, passwordBasedKeySize)
+
+	default:
+		return nil, fmt.Errorf("unsupported key algorithm: %v", f.KeyAlgo)
+	}
 }
 
 // Password returns password-based Credentials with the specified password.
diff --git a/vault/format.go b/vault/format.go
index 1b3b6f4c5..ca66760be 100644
--- a/vault/format.go
+++ b/vault/format.go
@@ -5,6 +5,7 @@
 type Format struct {
 	Version    string `json:"version"`
 	UniqueID   []byte `json:"uniqueID"`
+	KeyAlgo    string `json:"keyAlgo"`
 	Encryption string `json:"encryption"`
 	Checksum   string `json:"checksum"`
 }
diff --git a/vault/vault.go b/vault/vault.go
index bb9f2740e..b5eaee0f9 100644
--- a/vault/vault.go
+++ b/vault/vault.go
@@ -284,7 +284,15 @@ func Create(
 	if _, err := io.ReadFull(rand.Reader, v.format.UniqueID); err != nil {
 		return nil, err
 	}
-	v.masterKey = vaultCreds.getMasterKey(v.format.UniqueID)
+	if v.format.KeyAlgo == "" {
+		v.format.KeyAlgo = defaultKeyAlgorithm
+
+	}
+	var err error
+	v.masterKey, err = vaultCreds.getMasterKey(&v.format)
+	if err != nil {
+		return nil, err
+	}
 
 	formatBytes, err := json.Marshal(&v.format)
 	if err != nil {
@@ -367,7 +375,10 @@ func Open(vaultStorage blob.Storage, vaultCreds Credentials) (*Vault, error) {
 		return nil, err
 	}
 
-	v.masterKey = vaultCreds.getMasterKey(v.format.UniqueID)
+	v.masterKey, err = vaultCreds.getMasterKey(&v.format)
+	if err != nil {
+		return nil, err
+	}
 	v.itemPrefix = prefix
 
 	cfgData, err := v.decryptBlock(blocks[offset+1])