/etc/ipsec.secrets is in strongswan-starter 5.1.2-0ubuntu2.
This file is owned by root:root, with mode 0o600.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | # This file holds shared secrets or RSA private keys for authentication.
# RSA private key for this host, authenticating it to any other host
# which knows the public part. Suitable public keys, for ipsec.conf, DNS,
# or configuration of other implementations, can be extracted conveniently
# with "ipsec showhostkey".
|