diff --git a/CMakeLists.txt b/CMakeLists.txt
index 157b4ef..75c634d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,11 @@ project(simple-dict-server C)
 SET(CMAKE_BUILD_TYPE "Release")
 
 add_definitions(-DLISTEN_ON_IPV6)
+IF(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    add_definitions("-DCPUBIT64")
+ELSE()
+    add_definitions("-DCPUBIT32")
+ENDIF()
 
 include_directories("/usr/local/include")
 link_directories("/usr/local/lib")
@@ -14,6 +19,7 @@ add_executable(simple-dict-client client.c)
 add_executable(migrate migrate.c)
 add_executable(cfgwriter cfgwriter.c)
 
+target_link_libraries(dict smd5)
 target_link_libraries(simple-dict-server dict spb pthread)
 target_link_libraries(simple-dict-client pthread)
 target_link_libraries(migrate spb)
diff --git a/client.c b/client.c
index b90aac7..8a9a985 100644
--- a/client.c
+++ b/client.c
@@ -92,7 +92,16 @@ int main(int argc,char *argv[]) {   //usage: ./client host port
                     fclose(fp);
                     printf("Send count:%u\n", len);
                 } else puts("Open file error!");
-            } else {
+            } else if(!strcmp(buf, "2md5")) {
+                uint8_t md5_vals[16];
+                printf("Enter md5 string:");
+                for(int i = 0; i < 16; i++) scanf("%02x", &md5_vals[i]);
+                printf("Read md5:");
+                for(int i = 0; i < 16; i++) printf("%02x", (uint8_t)(md5_vals[i]));
+                putchar('\n');
+                send(sockfd, md5_vals, 16, 0);
+            }
+            else {
                 send(sockfd, buf, strlen(buf), 0);
                 if(!strcmp(buf, "quit")) exit(EXIT_SUCCESS);
             }
diff --git a/dict.c b/dict.c
index 1edb80c..a78ecf7 100644
--- a/dict.c
+++ b/dict.c
@@ -1,10 +1,15 @@
 #include <stdio.h>
 #include <sys/stat.h>
+#include <stdlib.h>
+#include <simplemd5.h>
 #include "dict.h"
 
 static FILE *fp = NULL;
 static int lock = 0;
 static char* filepath;
+static uint8_t* dict_md5;
+#define _dict_md5_4 ((uint32_t*)dict_md5)
+#define _dict_md5_2 ((uint64_t*)dict_md5)
 
 uint32_t last_nonnull(char* p, uint32_t max_size) {
     if(max_size > 1) while(!p[max_size - 1]) max_size--;
@@ -16,7 +21,23 @@ int init_dict(char* file_path) {
     if(fp) {
         lock = LOCK_UN;
         filepath = file_path;
-        return 1;
+        size_t size = get_dict_size();
+        uint8_t* dict_buff = (uint8_t*)malloc(size);
+        if(dict_buff) {
+            if(fread(dict_buff, size, 1, fp) == 1) {
+                if(dict_md5) free(dict_md5);
+                dict_md5 = md5(dict_buff, size);
+                free(dict_buff);
+                return 1;
+            } else {
+                free(dict_buff);
+                puts("Read dict error");
+                return 0;
+            }
+        } else {
+            puts("Allocate memory error");
+            return 0; 
+        }
     } else {
         puts("Open dict error");
         return 0;
@@ -48,3 +69,17 @@ off_t get_dict_size() {
     if(stat(filepath, &statbuf)==0) return statbuf.st_size;
     else return -1;
 }
+
+int is_md5_equal(uint8_t* digest) {
+    #ifdef CPUBIT64
+        uint64_t* digest2 = (uint64_t*)digest;
+        return (digest2[0] == _dict_md5_2[0]) &&
+                (digest2[1] == _dict_md5_2[1]);
+    #else
+        uint32_t* digest4 = (uint32_t*)digest;
+        return (digest4[0] == _dict_md5_4[0]) &&
+                (digest4[1] == _dict_md5_4[1]) &&
+                (digest4[2] == _dict_md5_4[2]) &&
+                (digest4[3] == _dict_md5_4[3]);
+    #endif
+}
diff --git a/dict.h b/dict.h
index 737029e..ee116c1 100644
--- a/dict.h
+++ b/dict.h
@@ -20,5 +20,6 @@ int init_dict(char* file_path);
 FILE *open_dict(int lock_type);
 void close_dict();
 off_t get_dict_size();
+int is_md5_equal(uint8_t* digest);
 
 #endif
\ No newline at end of file
diff --git a/server.c b/server.c
index a1c617a..23a8f13 100644
--- a/server.c
+++ b/server.c
@@ -72,6 +72,7 @@ int s1_get(THREADTIMER *timer);
 int s2_set(THREADTIMER *timer);
 int s3_set_data(THREADTIMER *timer);
 int s4_del(THREADTIMER *timer);
+int s5_md5(THREADTIMER *timer);
 
 int bind_server(uint16_t port, u_int try_times) {
     int fail_count = 0;
@@ -168,6 +169,7 @@ int s0_init(THREADTIMER *timer) {
     if(!strcmp("get", timer->data)) timer->status = 1;
     else if(!strcmp(setpass, timer->data)) timer->status = 2;
     else if(!strcmp(delpass, timer->data)) timer->status = 4;
+    else if(!strcmp("md5", timer->data)) timer->status = 5;
     else if(!strcmp("cat", timer->data)) return send_all(timer);
     else if(!strcmp("quit", timer->data)) return 0;
     return send_data(timer->accept_fd, timer->data, timer->numbytes);
@@ -280,6 +282,12 @@ int s4_del(THREADTIMER *timer) {
     return close_and_send(timer, "null", 4);
 }
 
+int s5_md5(THREADTIMER *timer) {
+    timer->status = 0;
+    if(is_md5_equal(timer->data)) return send_data(timer->accept_fd, "null", 4);
+    else return send_data(timer->accept_fd, "nequ", 4);
+}
+
 int check_buffer(THREADTIMER *timer) {
     printf("Status: %d\n", timer->status);
     switch(timer->status) {
@@ -289,6 +297,7 @@ int check_buffer(THREADTIMER *timer) {
         case 2: return s2_set(timer); break;
         case 3: return s3_set_data(timer); break;
         case 4: return s4_del(timer); break;
+        case 5: return s5_md5(timer); break;
         default: return -1; break;
     }
 }
@@ -382,6 +391,7 @@ void handle_accept(void *p) {
                 puts("Check buffer");
                 take_word(p, cfg->pwd);
                 take_word(p, "cat");
+                take_word(p, "md5");
                 take_word(p, setpass);
                 take_word(p, delpass);
                 if(timer_pointer_of(p)->numbytes > 0) chkbuf(p);