Editing Red/black concept (section)

{{Other uses|Red-black (disambiguation){{!}}Red-black}}
{{Short description|Careful segregation of signals in cryptographic systems}}
[[Image:RedBlack.png|thumb|300px|right|Red/black box]]

The '''red/black concept''', sometimes called the '''red–black architecture'''<ref>{{cite web|author=David Kleidermacher|url=https://militaryembedded.com/cyber/cybersecurity/bringing-android-military-communications-devices|title=Bringing Android to military communications devices|year=2010}}</ref>
or '''red/black engineering''',<ref>{{cite web|url=https://www.wbdg.org/ccb/FEDMIL/hdbk232a.pdf|title=MIL-HDBK-232A: Red/black engineering -- installation guidelines|year=1988|url-status=dead|archive-url=https://web.archive.org/web/20070714145117/http://www.wbdg.org/ccb/FEDMIL/hdbk232a.pdf|archive-date=2007-07-14}}</ref><ref>{{cite web|url=http://www.gocsc.com/UserFiles/File/Ortronics/WhitePaperGovtv5AUG2011FINAL.pdf|title=Cabling for Secure Government Networks|url-status=dead|archive-url=https://web.archive.org/web/20120519024601/http://www.gocsc.com/UserFiles/File/Ortronics/WhitePaperGovtv5AUG2011FINAL.pdf|archive-date=2012-05-19}}</ref>
refers to the careful segregation in [[cryptographic]] systems of signals that contain sensitive or [[Classified information|classified]] [[plaintext]] information ('''red signals''') from those that carry encrypted information, or [[ciphertext]] ('''black signals'''). Therefore, the '''red''' side is usually considered the internal side, and the '''black''' side the more public side, with often some sort of [[Guard (information security)|guard]], [[Firewall (computing)|firewall]] or [[Unidirectional network|data-diode]] between the two.

In [[NSA]] jargon, encryption devices are often called [[Blacker (security)|blackers]], because they convert red signals to black. [[Tempest (codename)|TEMPEST]] standards spelled out in Tempest/[[NSTISSAM TEMPEST/2-95|2-95]] specify shielding or a minimum physical distance between wires or equipment carrying or processing red and black signals.<ref>{{cite web|url = http://cryptome.org/tempest-2-95.htm|title = NSTISSAM TEMPEST/2-95|accessdate = 2007-12-02|last = McConnell |first = J. M.|date =  12 December 1995|archiveurl = https://web.archive.org/web/20070408221244/http://cryptome.org/tempest-2-95.htm|archivedate = 2007-04-08}}</ref>

Different organizations have differing requirements for the separation of red and black [[fiber-optic cable]]s.

Red/black terminology is also applied to cryptographic [[key (cryptography)|keys]]. Black keys have themselves been encrypted with  a "key encryption key" (KEK) and are therefore benign.  Red keys are not encrypted and must be treated as highly sensitive material.<ref>{{cite book|title=Designing Storage Area Networks|first= Tom |last=Clark|year=2003|publisher=Addison-Wesley Professional |url= https://books.google.com/books?id=xKikTYXkXZEC&q=%22red/black+concept%22&pg=PA483|isbn=0-321-13650-0}}</ref>