diff --git a/arvo/hoon.hoon b/arvo/hoon.hoon
index b084b8902..615d3414e 100644
--- a/arvo/hoon.hoon
+++ b/arvo/hoon.hoon
@@ -4189,6 +4189,77 @@
           df4d.225e.2d56.7fd6.1395.a3f8.c582
     (cut 3 [a 1] b)
   --
+::
+++  ob
+  |%
+  ++  feen                                              ::  conceal structure v2
+    |=  pyn=@  ^-  @
+    ?:  &((gte pyn 0x1.0000) (lte pyn 0xffff.ffff))
+      (add 0x1.0000 (fice (sub pyn 0x1.0000)))
+    ?:  &((gte pyn 0x1.0000.0000) (lte pyn 0xffff.ffff.ffff.ffff))
+      =+  lo=(dis pyn 0xffff.ffff)
+      =+  hi=(dis pyn 0xffff.ffff.0000.0000)
+      %+  con  hi
+      (add 0x1.0000 (fice (sub lo 0x1.0000)))
+    pyn
+  ::
+  ++  fend                                              ::  restore structure v2
+    |=  cry=@  ^-  @
+    ?:  &((gte cry 0x1.0000) (lte cry 0xffff.ffff))
+      (add 0x1.0000 (teil (sub cry 0x1.0000)))
+    ?:  &((gte cry 0x1.0000.0000) (lte cry 0xffff.ffff.ffff.ffff))
+      =+  lo=(dis cry 0xffff.ffff)
+      =+  hi=(dis cry 0xffff.ffff.0000.0000)
+      %+  con  hi
+      (add 0x1.0000 (teil (sub lo 0x1.0000)))
+    cry
+  ::
+  ++  fice                                              ::  adapted from
+    |=  nor=@                                           ::  black and rogaway
+    ^-  @                                               ::  "ciphers with
+    =+  ^=  sel                                         ::   arbitrary finite
+    %+  rynd  2                                         ::   domains", 2002
+    %+  rynd  1
+    %+  rynd  0
+    [(mod nor 65.535) (div nor 65.535)]
+    (add (mul 65.535 -.sel) +.sel)
+  ::
+  ++  teil                                              ::  reverse ++fice
+    |=  vip=@
+    ^-  @
+    =+  ^=  sel
+    %+  rund  0
+    %+  rund  1
+    %+  rund  2
+    [(mod vip 65.535) (div vip 65.535)]
+    (add (mul 65.535 -.sel) +.sel)
+  ::
+  ++  rynd                                              ::  feistel round
+    |=  [n=@ l=@ r=@]
+    ^-  [@ @]
+    :-  r
+    ?~  (mod n 2)
+      (~(sum fo 65.535) l (en:aesc (snag n raku) r))
+    (~(sum fo 65.536) l (en:aesc (snag n raku) r))
+  ::
+  ++  rund                                              ::  reverse round
+    |=  [n=@ l=@ r=@]
+    ^-  [@ @]
+    :-  r
+    ?~  (mod n 2)
+      (~(dif fo 65.535) l (en:aesc (snag n raku) r))
+    (~(dif fo 65.536) l (en:aesc (snag n raku) r))
+  ::
+  ++  raku
+    ^-  (list ,@ux)
+    :~  0x15f6.25e3.083a.eb3e.7a55.d4db.fb99.32a3.
+          43af.2750.219e.8a24.e5f8.fac3.6c36.f968
+        0xf2ff.24fe.54d0.1abd.4b2a.d8aa.4402.8e88.
+          e82f.19ec.948d.b1bb.ed2e.f791.83a3.8133
+        0xa3d8.6a7b.400e.9e91.187d.91a7.6942.f34a.
+          6f5f.ab8e.88b9.c089.b2dc.95a6.aed5.e3a4
+    ==
+  --
 ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 ::                section 2eO, virtualization           ::
 ::