strongSwan utility and crypto library

 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 the underlying libraries of charon and other strongSwan
 components. It is built in a modular way and is extendable through various
 plugins.
 .
 Some default (as specified by the strongSwan projet) plugins are included.
 For libstrongswan (cryptographic backends, URI fetchers and database layers):
  - constraints (X.509 certificate advanced constraint checking)
  - dnskey (Parse RFC 4034 public keys)
  - drbg (NIST SP-800-90A Deterministic Random Bit Generator)
  - nonce (Default nonce generation plugin)
  - openssl (Crypto backend based on OpenSSL, provides
    RSA/ECDSA/DH/ECDH/ciphers/hashers/HMAC/X.509/CRL/RNG)
  - pem (PEM encoding/decoding routines)
  - pkcs1 (PKCS#1 encoding/decoding routines)
  - pkcs8 (PKCS#8 decoding routines)
  - pubkey (Wrapper to handle raw public keys as trusted certificates)
  - random (RNG reading from /dev/[u]random)
  - revocation (X.509 CRL/OCSP revocation checking)
  - x509 (Advanced X.509 plugin for parsing/generating X.509 certificates/CRLs
    and OCSP messages)
  - attr (Provides IKE attributes configured in strongswan.conf)
  - kernel-netlink [linux] (IPsec/Networking kernel interface using Linux
    Netlink)
  - kernel-pfkey [kfreebsd] (IPsec kernel interface using PF_KEY)
  - kernel-pfroute [kfreebsd] (Networking kernel interface using PF_ROUTE)
  - resolve (Writes name servers received via IKE to a resolv.conf file or
    installs them via resolvconf(8))