7 \epigraph{``Unfortunately, the computer security and cryptology communities have drifted apart over the last 25 years. Security people don't always understand the available crypto tools, and crypto people don't always understand the real-world problems.''}{Ross Anderson in \cite{anderson2008security}}
11 This guide arose out of the need for system administrators to have an
12 updated, solid, well researched and thought-through guide for configuring SSL,
13 PGP, SSH and other cryptographic tools in the post-Snowden age. Triggered by the NSA
14 leaks in the summer of 2013, many system administrators and IT security
15 officers saw the need to strengthen their encryption settings.
16 This guide is specifically written for these system administrators.
20 As Schneier noted in \cite{Sch13}, it seems that intelligence agencies and
21 adversaries on the Internet are not breaking so much the mathematics of
22 encryption per se, but rather use software and hardware weaknesses, subvert
23 standardization processes, plant backdoors, rig random number generators and
24 most of all exploit careless settings in server configurations and encryption
25 systems to listen in on private communications. Worst of all, most
26 communication on the internet is not encrypted at all by default
27 (for SMTP, opportunistic TLS would be a solution).
31 This guide can only address one aspect of securing our information systems:
32 getting the crypto settings right to the best of the authors' current
33 knowledge. Other attacks, as the above mentioned, require different protection
34 schemes which are not covered in this guide. This guide is not an introduction
35 to cryptography. For background information on cryptography and cryptoanalysis
36 we would like to refer the reader to the the references in chapter
37 \ref{section:Links} and \ref{section:Suggested_Reading} at the end of this
42 The focus of this guide is merely to give current \emph{best practices for
43 configuring complex cipher suites} and related parameters in a \emph{copy \&
44 paste-able manner}. The guide tries to stay as concise as is possible for such
45 a complex topic as cryptography. Naturaly, it can not be complete. Instead,
46 there are many excellent guides (\cite{ii2011ecrypt},\cite{TR02102}) and best
47 practice documents available when it comes to cryptography. However none of
48 them focuses specifically on what an average system administrator needs for
49 hardening his or her systems' crypto settings.
52 This guide tries to fill this gap.
57 %The guide was produced in an open source manner: every step of editing can be
58 %traced back to a specific author via our version control system.