urbit/pkg/base-dev/lib/bip/b173.hoon
2021-08-10 16:13:27 +03:00

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:: BIP173: Bech32 Addresses
:: https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki
::
:: Heavily copies:
:: https://github.com/bitcoinjs/bech32/blob/master/index.js
::
/- sur=bitcoin
/+ bcu=bitcoin-utils
=, sur
=, bcu
|%
++ prefixes
^- (map network tape)
(my [[%main "bc"] [%testnet "tb"] ~])
++ charset "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
+$ raw-decoded [hrp=tape data=(list @) checksum=(list @)]
:: below is a port of: https://github.com/bitcoinjs/bech32/blob/master/index.js
::
++ 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 @)]
^- ?
%- |=(a=@ =(1 a))
%- polymod
(weld (expand-hrp hrp) data-and-checksum)
::
++ checksum
|= [hrp=tape data=(list @)]
^- (list @)
:: xor 1 with the polymod
::
=/ pmod=@
%+ mix 1
%- polymod
(zing ~[(expand-hrp hrp) data (reap 6 0)])
%+ turn (gulf 0 5)
|=(i=@ (dis 31 (rsh [0 (mul 5 (sub 5 i))] pmod)))
::
++ charset-to-value
|= c=@tD
^- (unit @)
(find ~[c] charset)
++ value-to-charset
|= value=@
^- (unit @tD)
?: (gth value 31) ~
`(snag value 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)))
==
:: data should be 5bit words
::
++ encode-raw
|= [hrp=tape data=(list @)]
^- cord
=/ combined=(list @)
(weld data (checksum hrp data))
%- crip
(zing ~[hrp "1" (tape (murn combined value-to-charset))])
++ decode-raw
|= body=cord
^- (unit raw-decoded)
=/ bech (cass (trip body)) :: 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
~
?. (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)]
:: +from-address: BIP173 bech32 address encoding to hex
:: https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki
:: expects to drop a leading 5-bit 0 (the witness version)
::
++ from-address
|= body=cord
^- hexb
~| "Invalid bech32 address"
=/ d=(unit raw-decoded) (decode-raw body)
?> ?=(^ d)
=/ bs=bits (from-atoms:bit 5 data.u.d)
=/ byt-len=@ (div (sub wid.bs 5) 8)
?> =(5^0b0 (take:bit 5 bs))
?> ?| =(20 byt-len)
=(32 byt-len)
==
[byt-len `@ux`dat:(take:bit (mul 8 byt-len) (drop:bit 5 bs))]
:: pubkey is the 33 byte ECC compressed public key
::
++ encode-pubkey
|= [=network pubkey=byts]
^- (unit cord)
?. =(33 wid.pubkey)
~|('pubkey must be a 33 byte ECC compressed public key' !!)
=/ prefix (~(get by prefixes) network)
?~ prefix ~
:- ~
%+ encode-raw u.prefix
[0v0 (to-atoms:bit 5 [160 `@ub`dat:(hash-160 pubkey)])]
--