better way to import key and add repository

.github/workflows/build.yml

@@ -33,10 +33,15 @@ jobs:
 
     - name: Install additional dependencies
       run: |
-        sudo apt-key adv --fetch-keys 'https://download.01.org/intel-sgx/sgx_repo/ubuntu/intel-sgx-deb.key'
-        sudo add-apt-repository 'deb https://download.01.org/intel-sgx/sgx_repo/ubuntu focal main'
-        sudo apt-key adv --fetch-keys 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-        sudo add-apt-repository 'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-11 main'
+        add_repository_with_key() {
+            gpg_key="$1.gpg"
+            cat "$1" | gpg --dearmor > "$gpg_key"
+            sudo install -o root -g root -m 644 "$gpg_key" /usr/share/keyrings/
+            sudo echo "deb [arch=amd64 signed-by=/usr/share/keyrings/$gpg_key] $2" >> /etc/apt/sources.list.d/additional-dependencies-focal.list
+            sudo rm "$gpg_key"
+        }
+        add_repository_with_key intel-sgx-deb.key "https://download.01.org/intel-sgx/sgx_repo/ubuntu focal main"
+        add_repository_with_key llvm-snapshot.gpg.key "http://apt.llvm.org/focal/ llvm-toolchain-focal-11 main"
         sudo apt-get update -y
         sudo apt-get install -y faketime protobuf-compiler libsgx-dcap-ql-dev clang-11 musl-tools