IPSec

Compatible Nitrokeys
3A/C/Mini	Passkey	HSM 2	Pro 2	FIDO2	Storage 2	Start	U2F
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Strong Swan works using the PKCS#11 driver. Basically follow these steps:

1. Generate a key on Nitrokey via pkcs11-tool. In this example it’s a 4096 bit RSA key.

   $ pkcs11-tool --module /usr/lib/x86_64-linux-gnu/pkcs11/opensc-pkcs11.so -l -k --key-type rsa:4096 --id 10 --label 'Staging Access'
   

2. Generate a certificate signing request via openssl + pkcs11 module

   $ openssl
   OpenSSL> engine dynamic -pre SO_PATH:/usr/lib/x86_64-linux-gnu/engines-1.1/pkcs11.so -pre ID:pkcs11 -pre LIST_ADD:1 -pre LOAD -pre MODULE_PATH:/usr/lib/x86_64-linux-gnu/pkcs11/opensc-pkcs11.so
   OpenSSL> req -engine pkcs11 -sha256 -new -key id_10 -keyform engine -out user@email.com-staging-cert.csr -subj '/C=GB/L=Cambridge/O=Organization/OU=Staging Access/CN=user@email.com/emailAddress=user@email.com'
   

3. Sign the certificate with your certificate authority

4. Convert the certificate to DER

   $ openssl x509 -in user@email.com-staging-cert.csr -out user@email.com-staging-cert.der -outform DER
   

5. Import the certificate into the Nitrokey via pkcs11-tool

   $ pkcs11-tool --module /usr/lib/x86_64-linux-gnu/pkcs11/opensc-pkcs11.so -l -y cert -w user@email.com-staging-cert.der --id 10 --label 'Staging Access'
   

6. Configure Strongswan to load opensc-pkcs11 module then to load the certificate on Nitrokey. Edit /etc/strongswan.d/charon/pkcs11.conf and add the following module:

   modules {
           Nitrokey {
                   path = /usr/lib/x86_64-linux-gnu/pkcs11/opensc-pkcs11.so
           }
   }
   

7. Initiate the VPN connection via IPSec/Strongswan, then prompt for Nitrokey PIN

8. VPN is now connected