strongswan has a critical bug that affects all versions < 5.0.4: "If the strongSwan "openssl" plugin is used for ECDSA signature verification, an empty, zeroed or otherwise invalid signature is handled as a legitimate one." (https://lists.strongswan.org/pipermail/announce/2013-April/000078.html) Please update the ebuild, so that the new 5.0.4 version can be installed.
*** This bug has been marked as a duplicate of bug 468008 ***