ChaCha jets

[lukechampine]

See https://github.com/urbit/urbit/pull/6932 and https://github.com/urbit/urcrypt/pull/11

[yosoyubik]

While adding hints in ames to the chacha core to test the jets I ran into an issue (possibly leading zeros; turning off the jet hints works) when decrypting a path. Here's my reproduction:

[ key=0x71d9.8487.408e.3cce.b04c.4ae3.a1b1.c4ce.a735.f8e8.c12c.3d4e.a00f.93b7.a3a4.7e82
  sealed=652.078.580.583.155.565.646.659.752.617.586.680.254.982.084.430.047.517.057.294.537.824.250.770.520.721.797.308.354.123.707.327.318.654.085.324.192.428.305.251.288.953.136.879.526.309.005.313
  tag=269.817.066.975.889.528.516.941.313.127.535.944.222
  cyf=[wid=38 dat=212.750.563.768.270.046.676.238.820.835.841.623.463.818.336.011.104.727.367.926.878.471.398.543.329.446.719.894.343.377]
  pat=198.629.089.831.792.245.670.330.659.320.620.482.115.670.229.676.301.490.323.664.083.653.514.959.207.157.527.522.531.914
]
> (cue pat)

/

++  open-path
  |=  [key=@uxI sealed=@]
  ^-  path
  =/  keys  (hash 64 key)
  =+  ;;([tag=@ cyf=byts] (cue sealed))
  =/  pat  dat:(decrypt (end 8 keys) tag cyf)
  :: ?>  (const-cmp tag (keyed-hash (rsh 8 keys) 16 pat))   :: XX FIXME
  ~&  [key=key sealed=sealed tag=tag cyf=cyf pat=pat]
  ;;(path (cue pat))

(fyi, confirmed that the jet is actually called)

[joemfb]

I've pushed jb/chacha, which fixes up the jet dashboard declarations for %zuse 410 (hoon 137). Using that branch to test urbit/urbit#6978, all tests fail.