diff --git a/main.go b/main.go
index 6e90c09..966b407 100644
--- a/main.go
+++ b/main.go
@@ -5,8 +5,7 @@ package main
 
 import (
 	"bytes"
-	"context"
-	"crypto/md5" //#nosec
+	"context" //#nosec
 	"embed"
 	"encoding/json"
 	"fmt"
@@ -24,7 +23,9 @@ import (
 	"github.com/gin-contrib/gzip"
 	"github.com/gin-gonic/gin"
 	"github.com/soulteary/hosts-blackhole/internal/logger"
-	provider "github.com/soulteary/hosts-blackhole/pkg/provider"
+	"github.com/soulteary/hosts-blackhole/pkg/crypto"
+	"github.com/soulteary/hosts-blackhole/pkg/provider"
+	"github.com/soulteary/hosts-blackhole/pkg/system"
 	flag "github.com/spf13/pflag"
 )
 
@@ -176,7 +177,7 @@ func main() {
 			if err != nil {
 				log.Fatal("程序无法创建缓存数据: ", err)
 			}
-			provider.ManualGC()
+			system.ManualGC()
 		}
 
 		c.Redirect(302, ROUTE_LIST)
@@ -248,8 +249,7 @@ func main() {
 // https://github.com/gin-gonic/gin/issues/1222
 func optimizeResourceCacheTime() gin.HandlerFunc {
 	data := []byte(time.Now().String())
-	/* #nosec */
-	etag := fmt.Sprintf("W/%x", md5.Sum(data))
+	etag := crypto.ETag(data)
 	return func(c *gin.Context) {
 		if strings.HasPrefix(c.Request.RequestURI, ROUTE_HOMEPAGE) ||
 			strings.HasPrefix(c.Request.RequestURI, ROUTE_FAVICON) {
diff --git a/pkg/crypto/md5.go b/pkg/crypto/md5.go
new file mode 100644
index 0000000..e7067c7
--- /dev/null
+++ b/pkg/crypto/md5.go
@@ -0,0 +1,18 @@
+package crypto
+
+import (
+	"crypto/md5" //#nosec
+	"fmt"
+)
+
+func Md5(str string) string {
+	data := []byte(str)
+	/* #nosec */
+	has := md5.Sum(data)
+	return fmt.Sprintf("%x", has)
+}
+
+func ETag(data []byte) string {
+	/* #nosec */
+	return fmt.Sprintf("W/%x", md5.Sum(data))
+}
diff --git a/pkg/provider/common.go b/pkg/provider/common.go
index 4d105a7..ea41005 100644
--- a/pkg/provider/common.go
+++ b/pkg/provider/common.go
@@ -2,19 +2,16 @@ package provider
 
 import (
 	"bufio"
-	"crypto/md5" //#nosec
-	"fmt"
 	"log"
 	"os"
 	"path/filepath"
-	"runtime"
-	"runtime/debug"
 	"sort"
 	"strconv"
 	"strings"
 	"time"
 
 	"github.com/soulteary/hosts-blackhole/internal/logger"
+	"github.com/soulteary/hosts-blackhole/pkg/crypto"
 )
 
 type Lines struct {
@@ -38,13 +35,6 @@ const baseDir = "./"
 var cacheKey = ""
 var cacheHash = ""
 
-func calcMd5(str string) string {
-	data := []byte(str)
-	/* #nosec */
-	has := md5.Sum(data)
-	return fmt.Sprintf("%x", has)
-}
-
 func CacheHash(files []string, update bool) (string, string) {
 	sort.Strings(files)
 	key := ""
@@ -57,8 +47,8 @@ func CacheHash(files []string, update bool) (string, string) {
 		}
 	}
 
-	key = calcMd5(key)
-	val = calcMd5(val)
+	key = crypto.Md5(key)
+	val = crypto.Md5(val)
 
 	if update {
 		cacheKey = key
@@ -193,27 +183,3 @@ func Purge(files []string) (mixed []string, success bool) {
 
 	return mixed, true
 }
-
-func ManualGC() {
-	log := logger.GetLogger()
-
-	log.Info("Runtime Information:")
-
-	runtime.GC()
-	debug.FreeOSMemory()
-
-	var m runtime.MemStats
-	runtime.ReadMemStats(&m)
-
-	log.Infof(" MEM Alloc =        %10v MB", toMB(m.Alloc))
-	log.Infof(" MEM HeapAlloc =    %10v MB", toMB(m.HeapAlloc))
-	log.Infof(" MEM Sys =          %10v MB", toMB(m.Sys))
-	log.Infof(" MEM NumGC =        %10v", m.NumGC)
-	log.Infof(" RUN NumCPU =       %10d", runtime.NumCPU())
-	log.Infof(" RUN NumGoroutine = %10d", runtime.NumGoroutine())
-}
-
-func toMB(b uint64) uint64 {
-	const bytesInKB = 1024
-	return b / bytesInKB / bytesInKB
-}
diff --git a/pkg/system/gc.go b/pkg/system/gc.go
new file mode 100644
index 0000000..cf8bc95
--- /dev/null
+++ b/pkg/system/gc.go
@@ -0,0 +1,32 @@
+package system
+
+import (
+	"runtime"
+	"runtime/debug"
+
+	"github.com/soulteary/hosts-blackhole/internal/logger"
+)
+
+func ManualGC() {
+	log := logger.GetLogger()
+
+	log.Info("Runtime Information:")
+
+	runtime.GC()
+	debug.FreeOSMemory()
+
+	var m runtime.MemStats
+	runtime.ReadMemStats(&m)
+
+	log.Infof(" MEM Alloc =        %10v MB", toMB(m.Alloc))
+	log.Infof(" MEM HeapAlloc =    %10v MB", toMB(m.HeapAlloc))
+	log.Infof(" MEM Sys =          %10v MB", toMB(m.Sys))
+	log.Infof(" MEM NumGC =        %10v", m.NumGC)
+	log.Infof(" RUN NumCPU =       %10d", runtime.NumCPU())
+	log.Infof(" RUN NumGoroutine = %10d", runtime.NumGoroutine())
+}
+
+func toMB(b uint64) uint64 {
+	const bytesInKB = 1024
+	return b / bytesInKB / bytesInKB
+}