libstrongswan-standard-plugins 5.5.1-1ubuntu2 (amd64 binary) in ubuntu zesty

 The strongSwan VPN suite uses the native IPsec stack in the standard
 Linux kernel. It supports both the IKEv1 and IKEv2 protocols.
 .
 This package provides some common plugins for the strongSwan utility and
 cryptograhic library.
 .
 Included plugins are:
  - agent (RSA/ECDSA private key backend connecting to SSH-Agent)
  - gcm (GCM cipher mode wrapper)
  - openssl (Crypto backend based on OpenSSL, provides
    RSA/ECDSA/DH/ECDH/ciphers/hashers/HMAC/X.509/CRL/RNG)