diff --git a/.github/workflows/basic-python3.yml b/.github/workflows/basic-python3.yml
index b765ead3052..b55587a03da 100644
--- a/.github/workflows/basic-python3.yml
+++ b/.github/workflows/basic-python3.yml
@@ -23,7 +23,7 @@ jobs:
           #     gracefully, make them non-daemonic and use a suitable
           #     signalling mechanism such as an Event."
           - pytest --no-cov -k 'not test_BaseType_Unicode and not test_nestedStructure and not testLockedClass'
-          # - pytest --no-cov src/DIRAC/Core/Security/test
+          - pytest --no-cov src/DIRAC/Core/Security/test
 
     steps:
     - uses: actions/checkout@v2
diff --git a/src/DIRAC/Core/Security/m2crypto/X509Request.py b/src/DIRAC/Core/Security/m2crypto/X509Request.py
index 3db1134d0c4..bfaf95d67fa 100644
--- a/src/DIRAC/Core/Security/m2crypto/X509Request.py
+++ b/src/DIRAC/Core/Security/m2crypto/X509Request.py
@@ -88,7 +88,7 @@ def getPKey(self):
 
   def dumpPKey(self):
     """
-    Get the pkey as a string
+    Get the private as a string
 
     :returns: S_OK(PEM encoded PKey)
     """
@@ -168,6 +168,7 @@ def checkChain(self, chain):
 
     :param chain: :py:class:`X509Chain` object
     """
+
     if not self.__valid:
       return S_ERROR(DErrno.ENOCERT)
     retVal = chain.getCertInChain()
@@ -177,8 +178,11 @@ def checkChain(self, chain):
     chainPubKey = lastCert.getPublicKey()
     if not chainPubKey['OK']:
       return chainPubKey
-    chainPubKey = chainPubKey['Value'].as_pem(cipher=None, callback=M2Crypto.util.no_passphrase_callback)
-    reqPubKey = self.__reqObj.get_pubkey().as_pem(cipher=None, callback=M2Crypto.util.no_passphrase_callback)
+
+    # as_der will dump public key info, while as_pem
+    # dumps private key.
+    chainPubKey = chainPubKey['Value'].as_der()
+    reqPubKey = self.__reqObj.get_pubkey().as_der()
     if not chainPubKey == reqPubKey:
       return S_ERROR(DErrno.EX509, "Public keys do not match")