diff --git a/.github/workflows/verify-on-container.yml b/.github/workflows/verify-on-container.yml
index 9765d00..4bfad90 100644
--- a/.github/workflows/verify-on-container.yml
+++ b/.github/workflows/verify-on-container.yml
@@ -6,8 +6,8 @@ on:
 - push
 
 jobs:
-  ssh:
-    name: Connect to github.com
+  ssh-pem:
+    name: Connect to github.com (PEM format)
     runs-on: ubuntu-20.04
     container: ubuntu:20.04
     steps:
@@ -20,7 +20,47 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l /root/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: ubuntu-20.04
+    container: ubuntu:20.04
+    steps:
+    - name: Install packages
+      run: |
+        apt update
+        apt -y install openssh-client git
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l /root/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: ubuntu-20.04
+    container: ubuntu:20.04
+    steps:
+    - name: Install packages
+      run: |
+        apt update
+        apt -y install openssh-client git
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
     - name: print created files
       run: ls -l /root/.ssh
diff --git a/.github/workflows/verify-on-macos-1015.yml b/.github/workflows/verify-on-macos-1015.yml
index 4e7d2b9..d84eb55 100644
--- a/.github/workflows/verify-on-macos-1015.yml
+++ b/.github/workflows/verify-on-macos-1015.yml
@@ -6,8 +6,8 @@ on:
 - push
 
 jobs:
-  ssh:
-    name: Connect to github.com
+  ssh-pem:
+    name: Connect to github.com (PEM format)
     runs-on: macos-10.15
     steps:
     - name: Checkout source codes
@@ -15,7 +15,37 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: macos-10.15
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: macos-10.15
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
     - name: print created files
       run: ls -l ~/.ssh
@@ -30,7 +60,7 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
         name: ssh_key_name # optional
         config: | # optional
diff --git a/.github/workflows/verify-on-ubuntu-1604.yml b/.github/workflows/verify-on-ubuntu-1604.yml
index 3e20078..00e39fc 100644
--- a/.github/workflows/verify-on-ubuntu-1604.yml
+++ b/.github/workflows/verify-on-ubuntu-1604.yml
@@ -6,8 +6,8 @@ on:
 - push
 
 jobs:
-  ssh:
-    name: Connect to github.com
+  ssh-pem:
+    name: Connect to github.com (PEM format)
     runs-on: ubuntu-16.04
     steps:
     - name: Checkout source codes
@@ -15,7 +15,37 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: ubuntu-16.04
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: ubuntu-16.04
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
     - name: print created files
       run: ls -l ~/.ssh
@@ -30,7 +60,7 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
         name: ssh_key_name # optional
         config: | # optional
diff --git a/.github/workflows/verify-on-ubuntu-1804.yml b/.github/workflows/verify-on-ubuntu-1804.yml
index 2b7c31c..9aafc72 100644
--- a/.github/workflows/verify-on-ubuntu-1804.yml
+++ b/.github/workflows/verify-on-ubuntu-1804.yml
@@ -6,8 +6,8 @@ on:
 - push
 
 jobs:
-  ssh:
-    name: Connect to github.com
+  ssh-pem:
+    name: Connect to github.com (PEM format)
     runs-on: ubuntu-18.04
     steps:
     - name: Checkout source codes
@@ -15,7 +15,37 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: ubuntu-18.04
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: ubuntu-18.04
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
     - name: print created files
       run: ls -l ~/.ssh
@@ -30,7 +60,7 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
         name: ssh_key_name # optional
         config: | # optional
diff --git a/.github/workflows/verify-on-windows-server-2019.yml b/.github/workflows/verify-on-windows-server-2019.yml
index 4afd0bd..98ae64e 100644
--- a/.github/workflows/verify-on-windows-server-2019.yml
+++ b/.github/workflows/verify-on-windows-server-2019.yml
@@ -6,8 +6,8 @@ on:
 - push
 
 jobs:
-  ssh:
-    name: Connect to github.com
+  ssh-pem:
+    name: Connect to github.com (PEM format)
     runs-on: windows-2019
     steps:
     - name: Checkout source codes
@@ -15,7 +15,37 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: windows-2019
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls ~/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: windows-2019
+    steps:
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
     - name: print created files
       run: ls ~/.ssh
@@ -30,7 +60,7 @@ jobs:
     - name: Install SSH key
       uses: ./.
       with:
-        key: ${{ secrets.SSH_KEY }}
+        key: ${{ secrets.SSH_KEY_PEM }}
         known_hosts: ${{ secrets.KNOWN_HOSTS }}
         name: ssh_key_name # optional
         config: | # optional
@@ -39,6 +69,6 @@ jobs:
             User git
             IdentityFile ~/.ssh/ssh_key_name
     - name: print created files
-      run: ls ~/.ssh
+      run: ls -l ~/.ssh
     - name: git clone through SSH
       run: git clone github:shimataro/ssh-key-action.git tmp