section 2eN, pseudo-cryptography
================================
++un
Reversible scrambling core
++ un :: =(x (wred (wren x)))
|%
A core that contains arms that perform reversible scrambling operations.
Used in the `@p` phonetic base.
------------------------------------------------------------------------
++wren
Conceal structure
++ wren :: conceal structure
|= pyn=@ ^- @
=+ len=(met 3 pyn)
?: =(0 len)
0
=> .(len (dec len))
=+ mig=(zaft (xafo len (cut 3 [len 1] pyn)))
%+ can 3
%- flop ^- (list ,[@ @])
:- [1 mig]
|- ^- (list ,[@ @])
?: =(0 len)
~
=> .(len (dec len))
=+ mog=(zyft :(mix mig (end 3 1 len) (cut 3 [len 1] pyn)))
[[1 mog] $(mig mog)]
::
Scrambles a bytestring `pyn` by adding the current position to each
byte, looking it up in an s-box, and then performing the XOR operation
on the result, pushing it forward. Produces an atom.
`pyn` is an [atom]().
~zod/try=> `@ux`(wren:un 'testing')
0x30.bf6a.b9fe.7d8f
~zod/try=> `@ux`'testing'
0x67.6e69.7473.6574
~zod/try=> `@da`(wred:un (wren:un ~2001.2.5))
~2001.2.5
------------------------------------------------------------------------
++wred
Restore structure
++ wred :: restore structure
|= cry=@ ^- @
=+ len=(met 3 cry)
?: =(0 len)
0
=> .(len (dec len))
=+ mig=(cut 3 [len 1] cry)
%+ can 3
%- flop ^- (list ,[@ @])
:- [1 (xaro len (zart mig))]
|- ^- (list ,[@ @])
?: =(0 len)
~
=> .(len (dec len))
=+ mog=(cut 3 [len 1] cry)
[[1 :(mix mig (end 3 1 len) (zyrt mog))] $(mig mog)]
::
Unscrambles a bytestring `cry` by subtracting the current position from
each byte, looking it up in an s-box, and performing the XOR operation
on the result, pushing it forward. Produces an atom.
`cry` is an [atom]().
~zod/try=> (wred:un 0x30.bf6a.b9fe.7d8f)
29.113.321.805.538.676
~zod/try=> `@t`(wred:un 0x30.bf6a.b9fe.7d8f)
'testing'
~zod/try=> (wred:un (wren:un 200.038.426))
200.038.426
------------------------------------------------------------------------
++xafo
Add modulo 255
++ xafo |=([a=@ b=@] +((mod (add (dec b) a) 255)))
Produces the sum of two atoms modulo 255, encoded as a nonzero byte.
~zod/try=> (xafo:un 5 6)
11
~zod/try=> (xafo:un 256 20)
21
------------------------------------------------------------------------
++xaro
Subtract modulo 255
++ xaro |=([a=@ b=@] +((mod (add (dec b) (sub 255 (mod a 255))) 255)))
Produces the difference between two atoms modulo 255, encoded as a
nonzero byte.
~zod/try=> (xaro:un 17 57)
40
~zod/try=> (xaro:un 265 12)
2
------------------------------------------------------------------------
++zaft
Look up in 255 sub box
++ zaft :: forward 255-sbox
|= a=@D
=+ ^= b
0xcc.75bc.86c8.2fb1.9a42.f0b3.79a0.92ca.21f6.1e41.cde5.fcc0.
7e85.51ae.1005.c72d.1246.07e8.7c64.a914.8d69.d9f4.59c2.8038.
1f4a.dca2.6fdf.66f9.f561.a12e.5a16.f7b0.a39f.364e.cb70.7318.
1de1.ad31.63d1.abd4.db68.6a33.134d.a760.edee.5434.493a.e323.
930d.8f3d.3562.bb81.0b24.43cf.bea5.a6eb.52b4.0229.06b2.6704.
78c9.45ec.d75e.58af.c577.b7b9.c40e.017d.90c3.87f8.96fa.1153.
0372.7f30.1c32.ac83.ff17.c6e4.d36d.6b55.e2ce.8c71.8a5b.b6f3.
9d4b.eab5.8b3c.e7f2.a8fe.9574.5de0.bf20.3f15.9784.9939.5f9c.
e609.564f.d8a4.b825.9819.94aa.2c08.8e4c.9b22.477a.2840.3ed6.
3750.6ef1.44dd.89ef.6576.d00a.fbda.9ed2.3b6c.7b0c.bde9.2ade.
5c88.c182.481a.1b0f.2bfd.d591.2726.57ba
(cut 3 [(dec a) 1] b)
::
The inverse of [`++zart`](). Looks up a nonzero byte`a\` in a substiution
box with 255 values, producing a unique nonzero byte.
`a` is an [atom]() of one byte in length.
~zod/try=> (zaft:un 0x12)
42
~zod/try=> (zaft:un 0xff)
204
~zod/try=> (zaft:un 0x0)
! decrement-underflow
! exit
------------------------------------------------------------------------
++zart
Reverse look up in 255 sub box
++ zart :: reverse 255-sbox
|= a=@D
=+ ^= b
0x68.4f07.ea1c.73c9.75c2.efc8.d559.5125.f621.a7a8.8591.5613.
dd52.40eb.65a2.60b7.4bcb.1123.ceb0.1bd6.3c84.2906.b164.19b3.
1e95.5fec.ffbc.f187.fbe2.6680.7c77.d30e.e94a.9414.fd9a.017d.
3a7e.5a55.8ff5.8bf9.c181.e5b6.6ab2.35da.50aa.9293.3bc0.cdc6.
f3bf.1a58.4130.f844.3846.744e.36a0.f205.789e.32d8.5e54.5c22.
0f76.fce7.4569.0d99.d26e.e879.dc16.2df4.887f.1ffe.4dba.6f5d.
bbcc.2663.1762.aed7.af8a.ca20.dbb4.9bc7.a942.834c.105b.c4d4.
8202.3e61.a671.90e6.273d.bdab.3157.cfa4.0c2e.df86.2496.f7ed.
2b48.2a9d.5318.a343.d128.be9c.a5ad.6bb5.6dfa.c5e1.3408.128d.
2c04.0339.97a1.2ff0.49d0.eeb8.6c0a.0b37.b967.c347.d9ac.e072.
e409.7b9f.1598.1d3f.33de.8ce3.8970.8e7a
(cut 3 [(dec a) 1] b)
::
The inverse of [`++zaft`](). Looks up the index of a nonzero byte `a` in
the substitution box with 255 values, producing a unique nonzero byte.
`a` is an [atom]() of one byte in length.
~zod/try=> `@ux`(zart:un 204)
0xff
~zod/try=> `@ux`(zart:un 42)
0x12
------------------------------------------------------------------------
++zyft
Lookup byte in 256 sub box
++ zyft :: forward 256-sbox
|= a=@D
=+ ^= b
0xbb49.b71f.b881.b402.17e4.6b86.69b5.1647.115f.dddb.7ca5.
8371.4bd5.19a9.b092.605d.0d9b.e030.a0cc.78ba.5706.4d2d.
986a.768c.f8e8.c4c7.2f1c.effe.3cae.01c0.253e.65d3.3872.
ce0e.7a74.8ac6.daac.7e5c.6479.44ec.4143.3d20.4af0.ee6c.
c828.deca.0377.249f.ffcd.7b4f.eb7d.66f2.8951.042e.595a.
8e13.f9c3.a79a.f788.6199.9391.7fab.6200.4ce5.0758.e2f1.
7594.c945.d218.4248.afa1.e61a.54fb.1482.bea4.96a2.3473.
63c2.e7cb.155b.120a.4ed7.bfd8.b31b.4008.f329.fca3.5380.
9556.0cb2.8722.2bea.e96e.3ac5.d1bc.10e3.2c52.a62a.b1d6.
35aa.d05e.f6a8.0f3b.31ed.559d.09ad.f585.6d21.fd1d.8d67.
370b.26f4.70c1.b923.4684.6fbd.cf8b.5036.0539.9cdc.d93f.
9068.1edf.8f33.b632.d427.97fa.9ee1
(cut 3 [a 1] b)
::
The inverse of [`++zyrt`](). Looks up a byte `a` in a substituion box
with 256 values, producing a byte.
`a` is an [atom]() of one byte in length.
~zod/try=> (zyft:un 0x12)
57
~zod/try=> (zyft:un 0x0)
225
~zod/try=> (zyft:un 0xff)
187
------------------------------------------------------------------------
++zyrt
Reverse lookup byte in 256 sub box
++ zyrt :: reverse 256-sbox
|= a=@D
=+ ^= b
0x9fc8.2753.6e02.8fcf.8b35.2b20.5598.7caa.c9a9.30b0.9b48.
47ce.6371.80f6.407d.00dd.0aa5.ed10.ecb7.0f5a.5c3a.e605.
c077.4337.17bd.9eda.62a4.79a7.ccb8.44cd.8e64.1ec4.5b6b.
1842.ffd8.1dfb.fd07.f2f9.594c.3be3.73c6.2cb6.8438.e434.
8d3d.ea6a.5268.72db.a001.2e11.de8c.88d3.0369.4f7a.87e2.
860d.0991.25d0.16b9.978a.4bf4.2a1a.e96c.fa50.85b5.9aeb.
9dbb.b2d9.a2d1.7bba.66be.e81f.1946.29a8.f5d2.f30c.2499.
c1b3.6583.89e1.ee36.e0b4.6092.937e.d74e.2f6f.513e.9615.
9c5d.d581.e7ab.fe74.f01b.78b1.ae75.af57.0ec2.adc7.3245.
12bf.2314.3967.0806.31dc.cb94.d43f.493c.54a6.0421.c3a1.
1c4a.28ac.fc0b.26ca.5870.e576.f7f1.616d.905f.ef41.33bc.
df4d.225e.2d56.7fd6.1395.a3f8.c582
(cut 3 [a 1] b)
The inverse of [`++zyft`](/doc/hoon/library/2en#++zyft). Looks up a byte `a` in a substituion box
with 256 values, producing a byte.
`a` is an [atom]() of one byte in length.
~zod/try=> `@ux`(zyrt:un 57)
0x12
~zod/try=> `@ux`(zyrt:un 225)
0x0
~zod/try=> `@ux`(zyrt:un 187)
0xff