urbit/lib/bip173.hoon

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|%
+$ address ?([@uc [%bech32 @t]])
+$ decoded-bech32 [hrp=tape data=(list @) checksum=(list @)]
::
++ charset "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
::
++ hash-160
|= pubkey=@ux
^- @ux
=, ripemd:crypto
:: use shay to preserve little endian length when there are trailing zeros
=/ sha256 (swp 3 (shay 33 (swp 3 pubkey)))
(ripemd-160 [32 sha256])
:: Converts an atom to a list of n-bit numbers, flop to preserve big-endian
::
++ to-n-bit
|= [n=@ input=@]
^- (list @)
=/ bits (flop (rip 0 input))
=| ret=(list @)
|- ?~ bits ret
=/ n-bits (scag n ((list @) bits))
:: left-shift the "missing" number of bits
=/ num=@
%: lsh 0
(sub n (lent n-bits))
(rep 0 (flop n-bits))
==
$(ret (snoc ret num), bits (slag n ((list @) bits)))
::
++ polymod
|= values=(list @)
=/ gen=(list @ux)
~[0x3b6a.57b2 0x2650.8e6d 0x1ea1.19fa 0x3d42.33dd 0x2a14.62b3]
=/ chk=@ 1
|- ?~ values chk
=/ top (rsh 0 25 chk)
=. chk
(mix i.values (lsh 0 5 (dis chk 0x1ff.ffff)))
$(values t.values, chk (update-chk chk top gen))
::
++ update-chk
|= [chk=@ top=@ gen=(list @ux)]
=/ is (gulf 0 4)
|- ?~ is chk
?: =(1 (dis 1 (rsh 0 i.is top)))
$(is t.is, chk (mix chk (snag i.is gen)))
$(is t.is)
::
++ expand-hrp
|= hrp=tape
^- (list @)
=/ front (turn hrp |=(p=@tD (rsh 0 5 p)))
=/ back (turn hrp |=(p=@tD (dis 31 p)))
(zing ~[front ~[0] back])
::
++ verify-checksum
|= [hrp=tape data-and-checksum=(list @)]
%- polymod
(weld (expand-hrp hrp) data-and-checksum)
::
++ charset-to-value
|= c=@tD
^- (unit @)
(find ~[c] charset)
::
++ is-valid
|= [bech=tape last-1-pos=@] ^- ?
?& ?|(=((cass bech) bech) =((cuss bech) bech)) :: to upper or to lower is same as bech
(gte last-1-pos 1)
(lte (add last-1-pos 7) (lent bech))
(lte (lent bech) 90)
(levy bech |=(c=@tD (gte c 33)))
(levy bech |=(c=@tD (lte c 126)))
==
::
++ decode-bech32
|= bech=tape
^- (unit decoded-bech32)
=. bech (cass bech) :: to lowercase
=/ pos (flop (fand "1" bech))
?~ pos ~
=/ last-1=@ i.pos
?. (is-valid bech last-1) :: check bech32 validity (not segwit validity or checksum)
~
=/ hrp (scag last-1 bech)
=/ encoded-data-and-checksum=(list @)
(slag +(last-1) bech)
=/ data-and-checksum=(list @)
%+ murn encoded-data-and-checksum
charset-to-value
?. =((lent encoded-data-and-checksum) (lent data-and-checksum)) :: ensure all were in CHARSET
~
?. =(1 (verify-checksum hrp data-and-checksum))
~
=/ checksum-pos (sub (lent data-and-checksum) 6)
`[hrp (scag checksum-pos data-and-checksum) (slag checksum-pos data-and-checksum)]
::
++ decode-segwit
|= segwit=tape
^- (unit [witver=@ witprog=@ux])
~
--