After some research, I found this: http://opensource.apple.com/source/Security/Security-55471/sec/Security/SecBasePriv.h
So -34018 is errSecMissingEntitlement and the comment says
Internal error when a required entitlement isn't present.
Do you experience this error while running your unit tests? If so, this might help: https://stackoverflow.com/a/22305193/171933
This issue on github says that it only seems to happen while debugging from Xcode: https://github.com/soffes/sskeychain/issues/97 (also see https://stackoverflow.com/a/28256591/171933)
Hopefully some of this will help!