Don't use custom PBKDF2 function (#3952)

Instead, use golang.org/x/crypto/pbkdf2

models/user.go

@@ -32,6 +32,8 @@ import (
 	"github.com/gogits/gogs/modules/log"
 	"github.com/gogits/gogs/modules/markdown"
 	"github.com/gogits/gogs/modules/setting"
+
+	"golang.org/x/crypto/pbkdf2"
 )
 
 type UserType int
@@ -315,7 +317,7 @@ func (u *User) NewGitSig() *git.Signature {
 
 // EncodePasswd encodes password to safe format.
 func (u *User) EncodePasswd() {
-	newPasswd := base.PBKDF2([]byte(u.Passwd), []byte(u.Salt), 10000, 50, sha256.New)
+	newPasswd := pbkdf2.Key([]byte(u.Passwd), []byte(u.Salt), 10000, 50, sha256.New)
 	u.Passwd = fmt.Sprintf("%x", newPasswd)
 }
 

modules/base/tool.go

@@ -5,14 +5,12 @@
 package base
 
 import (
-	"crypto/hmac"
 	"crypto/md5"
 	"crypto/rand"
 	"crypto/sha1"
 	"encoding/base64"
 	"encoding/hex"
 	"fmt"
-	"hash"
 	"html/template"
 	"math"
 	"math/big"
@@ -110,45 +108,6 @@ func randomInt(max *big.Int) (int, error) {
 	return int(rand.Int64()), nil
 }
 
-// http://code.google.com/p/go/source/browse/pbkdf2/pbkdf2.go?repo=crypto
-// FIXME: use https://godoc.org/golang.org/x/crypto/pbkdf2?
-func PBKDF2(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
-	prf := hmac.New(h, password)
-	hashLen := prf.Size()
-	numBlocks := (keyLen + hashLen - 1) / hashLen
-
-	var buf [4]byte
-	dk := make([]byte, 0, numBlocks*hashLen)
-	U := make([]byte, hashLen)
-	for block := 1; block <= numBlocks; block++ {
-		// N.B.: || means concatenation, ^ means XOR
-		// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
-		// U_1 = PRF(password, salt || uint(i))
-		prf.Reset()
-		prf.Write(salt)
-		buf[0] = byte(block >> 24)
-		buf[1] = byte(block >> 16)
-		buf[2] = byte(block >> 8)
-		buf[3] = byte(block)
-		prf.Write(buf[:4])
-		dk = prf.Sum(dk)
-		T := dk[len(dk)-hashLen:]
-		copy(U, T)
-
-		// U_n = PRF(password, U_(n-1))
-		for n := 2; n <= iter; n++ {
-			prf.Reset()
-			prf.Write(U)
-			U = U[:0]
-			U = prf.Sum(U)
-			for x := range U {
-				T[x] ^= U[x]
-			}
-		}
-	}
-	return dk[:keyLen]
-}
-
 // verify time limit code
 func VerifyTimeLimitCode(data string, minutes int, code string) bool {
 	if len(code) <= 18 {