diff --git a/server/apps/exam/views.py b/server/apps/exam/views.py
index 4e89fa1..ceb0e89 100644
--- a/server/apps/exam/views.py
+++ b/server/apps/exam/views.py
@@ -27,6 +27,8 @@ from apps.exam.parse_word import interpret_text
 import os
 import shutil
 from django.db.models import Q
+from django_redis import get_redis_connection
+import uuid
 # Create your views here.
 
 EXCEL_PATH = os.path.join(settings.BASE_DIR,  "media/default/question.xlsx")
@@ -524,6 +526,7 @@ class ExamViewSet(CreateUpdateCustomMixin, ModelViewSet):
         now = timezone.now()
         if now < exam.open_time or now > exam.close_time:
             raise ParseError('不在考试时间范围')
+        ExamRecord.objects.filter(exam=exam, create_by=request.user, is_submited=False).delete()
         tests = ExamRecord.objects.filter(
                 exam=exam, create_by=request.user)
         chance_used = tests.count()
@@ -685,6 +688,9 @@ class ExamRecordViewSet(ListModelMixin, DestroyModelMixin, RetrieveModelMixin, G
                 courese_ids = [i.id for i in course]
                 current_date =  now_data.strftime('%Y-%m-%d')
                 cer_number = now_data.strftime('%Y%m%d')
+                # redis 连接并获取锁
+                redis_conn = get_redis_connection("redis")
+                identifier = acquire_lock(redis_conn, 'certificate', 10)
                 # 查询证明编号创建时间为最后一个
                 cer = Certificate.objects.latest('证书编号')
                 if cer:
@@ -706,10 +712,45 @@ class ExamRecordViewSet(ListModelMixin, DestroyModelMixin, RetrieveModelMixin, G
                 serializer = CertificateSerializer(data=data_dict)
                 serializer.is_valid(raise_exception=True)
                 serializer.save()
+                # 释放锁
+                if identifier:
+                    release_lock(redis_conn, 'certificate', identifier)
+                else:
+                    print("没有找到锁")
                
         er.took = (now - er.create_time).total_seconds()
         er.end_time = now
         er.belong_dept=request.user.dept
         er.is_submited = True
         er.save()
-        return Response(ExamRecordListSerializer(instance=er).data)
\ No newline at end of file
+        return Response(ExamRecordListSerializer(instance=er).data)
+    
+
+def acquire_lock(redis_conn, lock_name, ttl):
+    identifier = str(uuid.uuid4())
+    lock = redis_conn.set(lock_name, identifier, nx=True, ex=ttl)
+    return identifier if lock else None
+
+
+import redis
+def release_lock(redis_conn, lock_name, identifier):
+    with redis_conn.pipeline() as pipe:
+        try:
+            while True:
+                try:
+                    pipe.watch(lock_name)
+                    # 使用 multi/exec 模式来确保原子性
+                    if pipe.get(lock_name) == identifier:
+                        pipe.multi()
+                        pipe.delete(lock_name)
+                        pipe.execute()
+                        return True
+                    # 如果锁已经被修改，取消监视
+                    pipe.unwatch()
+                    return False
+                except redis.exceptions.WatchError:
+                    # 如果在监视期间锁被修改，重试
+                    continue
+        except redis.exceptions.RedisError as e:
+            print(f"Error releasing lock: {e}")
+            return False
\ No newline at end of file
diff --git a/server/server/settings.py b/server/server/settings.py
index b6998d2..97bed41 100644
--- a/server/server/settings.py
+++ b/server/server/settings.py
@@ -196,14 +196,14 @@ AUTHENTICATION_BACKENDS = (
 
 # 缓存配置
 CACHES = {
-    # "default": {
-    #     "BACKEND": "django_redis.cache.RedisCache",
-    #     "LOCATION": "redis://127.0.0.1:6379/9",
-    #     "OPTIONS": {
-    #         "CLIENT_CLASS": "django_redis.client.DefaultClient",
-    #         # "PICKLE_VERSION": -1
-    #     }
-    # }
+    "redis": {
+        "BACKEND": "django_redis.cache.RedisCache",
+        "LOCATION": "redis://127.0.0.1:6379/1",
+        "OPTIONS": {
+            "CLIENT_CLASS": "django_redis.client.DefaultClient",
+            # "PICKLE_VERSION": -1
+        }
+    },
     'default': {
         'BACKEND': 'django.core.cache.backends.filebased.FileBasedCache',
         'LOCATION': os.path.join(BASE_DIR, 'temp'),
diff --git a/ssl/testsearch.ctc.ac.cn.key b/ssl/testsearch.ctc.ac.cn.key
index cc65336..e2722d7 100644
--- a/ssl/testsearch.ctc.ac.cn.key
+++ b/ssl/testsearch.ctc.ac.cn.key
@@ -1,27 +1,27 @@
 -----BEGIN RSA PRIVATE KEY-----
-MIIEogIBAAKCAQEArs+Efx2qnceCl9/Z/SdzTxcIsasN0+mhCoINJV8wrBAeiyHU
-Dbmm+A4aEVYi4W3U2iw76IKLXuDlBhZ/cTHIuUGz2YwpeEwZPy1JfReFWz9Afj6m
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+WEjIAJ/wgFrUESBtur7OQerRKjkyyJxCczshHS5LdV22pLTzt71B4SqH
 -----END RSA PRIVATE KEY-----
\ No newline at end of file
diff --git a/ssl/testsearch.ctc.ac.cn.pem b/ssl/testsearch.ctc.ac.cn.pem
index 0a375f2..6cdcdb7 100644
--- a/ssl/testsearch.ctc.ac.cn.pem
+++ b/ssl/testsearch.ctc.ac.cn.pem
@@ -1,36 +1,36 @@
 -----BEGIN CERTIFICATE-----
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 -----END CERTIFICATE-----
 -----BEGIN CERTIFICATE-----
 MIIFBzCCA++gAwIBAgIRALIM7VUuMaC/NDp1KHQ76aswDQYJKoZIhvcNAQELBQAw