Add salt for every single user

modules/base/tool.go

@@ -6,12 +6,14 @@ package base
 
 import (
 	"bytes"
+	"crypto/hmac"
 	"crypto/md5"
 	"crypto/rand"
 	"crypto/sha1"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"hash"
 	"math"
 	"strconv"
 	"strings"
@@ -40,6 +42,44 @@ func GetRandomString(n int, alphabets ...byte) string {
 	return string(bytes)
 }
 
+// http://code.google.com/p/go/source/browse/pbkdf2/pbkdf2.go?repo=crypto
+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 {