Comment There in Knuth, so not "written out of history" (Score 3, Informative) 238
Knuth's TAOCP, Volume 2, Third Edition, Page 407:
"Historical note: It was revealed in 1998 that Clifford Cocks had considered encoding messages by the transformation $x^{pq} mod pq$ already in 1973, but his work was kept secret".
And that feels like the correct amount of recognition.