Document modhex

diff --git a/ykpersonalize.1 b/ykpersonalize.1
index bf8b69e6f888965120d80192508053d27d19a311..209027963f4a6d32fd336db9272dca9c75f1d95f 100644 (file)
--- a/ykpersonalize.1
+++ b/ykpersonalize.1
@@ -247,6 +247,20 @@ configuration, and the other in challenge-response mode).  Instead, a program ca
 sending USB HID feature reports to the token must be used to send it a challenge, and
 read the response.
 
+.SH Modhex
+Modhex is a way of writing hex digits where the \(lqdigits\(rq are
+chosen for being in the same place on most keyboard layouts.
+.TP
+To convert from hex to modhex, you can use
+.RS
+tr "[0123456789abcdef]" "[cbdefghijklnrtuv]"
+.RE
+.TP
+To convert the other way, use
+.RS
+tr "[cbdefghijklnrtuv]" "[0123456789abcdef]"
+.RE
+
 .SH BUGS
 Report ykpersonalize bugs in 
 .URL "https://github.com/Yubico/yubikey-personalization/issues" "the issue tracker"