urbit/lib/btc.hoon
2021-05-26 18:30:12 -07:00

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/- *btc
|%
:: big endian sha256: input and output are both MSB first (big endian)
::
++ sha256
|= =byts ^- hash256
:: if there are leading 0s, lshift by their amount after flip to little endian to preserve
=/ pad=@ (sub wid.byts (met 3 dat.byts))
=/ little-endian=@
(lsh 3 pad (swp 3 dat.byts))
%- hash256
:- 32
%+ swp 3
(shay wid.byts little-endian)
::
++ dsha256
|= =byts
(sha256 (sha256 byts))
::
++ hash-160
|= pubkey=@ux ^- hash160
=, ripemd:crypto
%- hash160
:- 20
%- ripemd-160
%- sha256 [(met 3 pubkey) pubkey]
::
++ to-script-pubkey
|= script=^buffer ^- ^buffer
%- zing
:~ ~[0x19 0x76 0xa9 0x14]
script
~[0x88 0xac]
==
++ address-to-script-pubkey
|= =address ^- ^buffer
=/ hex=byts
?- -.address
%bech32
(to-hex:bech32 address)
%legacy
=/ h=@ux (@ux +.address)
[(met 3 h) h]
==
?. =(wid.hex 20)
~|("Only 20-byte addresses supported" !!)
(to-script-pubkey (from-byts:buffer hex))
:: list of @ux that is big endian for hashing purposes
:: used to preserve 0s when concatenating byte sequences
::
++ buffer
|%
++ from-byts
|= =byts ^- ^buffer
=/ b=(list @ux)
(flop (rip 3 dat.byts))
=/ pad=@ (sub wid.byts (lent b))
(weld (reap pad 0x0) b)
:: converts an atom to a little endian buffer with wid length (trailing 0s)
:: atom 1 with wid=4 becomes ~[0x1 0x0 0x0 0x0]
:: 0xff11 with wid=8 becomes ~[0x11 0xff 0x0 0x0 0x0 0x0 0x0 0x0]
::
++ from-atom-le
|= [wid=@ a=@] ^- ^buffer
=/ b=(list @ux) (rip 3 a)
=/ pad=@ (sub wid (lent b))
(weld b (reap pad 0x0))
::
++ to-byts
|= b=^buffer ^- byts
[(lent b) (rep 3 (flop b))]
++ concat-as-byts
|= bs=(list ^buffer) ^- byts
%- to-byts (zing bs)
--
::
:: TODO: current status
:: - creates sighash for witness correctly
:: - creates sighash for 1-input legacy correctly
:: - don't know yet whether the sighash for multiple-input legacy is correct -- test w JS
::
++ unsigned-tx
=, buffer
|_ ut=unsigned:tx
++ sequence-buffer
|= =input:tx ^- ^buffer
(from-byts sequence.input)
::
++ outputs-buffer
|= =output:tx ^- ^buffer
%+ weld
(from-atom-le 8 value.output)
(address-to-script-pubkey address.output)
::
++ sighash
|= input-index=@ ^- hash256
?: (gte input-index (lent inputs.ut))
~|("Input index out of range" !!)
=/ =input:tx (snag input-index inputs.ut)
?: =(1 witness-ver.input)
(sighash-witness input)
(sighash-legacy input-index)
::
++ sighash-witness
|= =input:tx
|^ ^- hash256
=/ prevouts=byts
%- concat-as-byts (turn inputs.ut prevouts-buffer)
=/ sequences=byts
%- concat-as-byts (turn inputs.ut sequence-buffer)
=/ outputs=byts
%- concat-as-byts (turn outputs.ut outputs-buffer)
:: Hash inputs in order, as per BIP143 examples
::
=/ n-version=^buffer (from-atom-le 4 version.ut)
=/ hash-prevouts=^buffer
%- from-byts (dsha256 prevouts)
=/ hash-sequence=^buffer
%- from-byts (dsha256 sequences)
=/ outpoint=^buffer
%+ weld (from-byts tx-hash.input)
(from-atom-le 4 witness-ver.input)
=/ script-code=^buffer
%- to-script-pubkey
(slag 2 (from-byts script-pubkey.input))
=/ amount=^buffer
(from-atom-le 8 value.input)
=/ n-sequence=^buffer (sequence-buffer input)
=/ hash-outputs=^buffer
%- from-byts (dsha256 outputs)
=/ n-locktime=^buffer (from-atom-le 4 locktime.ut)
=/ n-hashtype=^buffer (from-atom-le 4 1)
%- dsha256
%- concat-as-byts
:~ n-version
hash-prevouts
hash-sequence
outpoint
script-code
amount
n-sequence
hash-outputs
n-locktime
n-hashtype
==
::
++ prevouts-buffer
|= =input:tx ^- ^buffer
%+ weld
(from-byts tx-hash.input)
(from-atom-le 4 witness-ver.input)
--
::
++ sighash-legacy
:: TODO: Not working--wrong sighash for multiple inputs (works for 1)
|= index-to-sign=@
|^ ^- hash256
=/ n-version=^buffer (from-atom-le 4 version.ut)
=/ num-inputs=^buffer ~[(@ux (lent inputs.ut))]
=/ prevouts=^buffer
%- zing
(turn inputs-with-index (cury prevouts-buffer index-to-sign))
=/ num-outputs=^buffer ~[(@ux (lent outputs.ut))]
=/ outputs=^buffer
%- zing (turn outputs.ut outputs-buffer)
=/ n-locktime=^buffer (from-atom-le 4 locktime.ut)
=/ n-hashtype=^buffer (from-atom-le 4 1) :: we only support SIGHASH_ALL
=/ struct=(list ^buffer)
:~ v=n-version
ni=num-inputs
prev=prevouts
no=num-outputs
os=outputs
lock=n-locktime
hash-type=n-hashtype
==
:: ~& >>> struct
(dsha256 (concat-as-byts struct))
::
++ inputs-with-index
^- (list [@ input:tx])
%+ turn (gulf 0 (dec (lent inputs.ut)))
|= i=@ [i (snag i inputs.ut)]
++ prevouts-buffer
|= [index-to-sign=@ index=@ =input:tx]
^- ^buffer
%- zing
:~ (from-byts tx-hash.input)
(from-atom-le 4 tx-index.input)
:: only insert script-pubkey if we're on the input index being signed
?: =(index-to-sign index)
(format-script-pubkey (from-byts script-pubkey.input))
~[0x0]
(from-byts sequence.input)
==
++ format-script-pubkey
|= spk=^buffer ^- ^buffer
?: =((^buffer ~[0x76 0xa9]) (scag 2 spk))
[0x19 spk]
spk
--
--
::
:: Converts a list of bits to a list of n-bit numbers
:: input-bits should be big-endian
::
++ bits
|%
:: rip atom a with num-bits. Preserve leading 0s, big endian
:: returns a list of bits
::
++ zeros-brip
|= [num-bits=@ a=@]
^- (list @)
=/ bits=(list @) (flop (rip 0 a))
=/ pad=@ (sub num-bits (lent bits))
(weld (reap pad 0) bits)
:: converts from bit list to a list of atoms each with bitwidth d(est)
::
++ convert
|= [d=@ bits=(list @)]
^- (list @)
=| ret=(list @)
|- ?~ bits ret
=/ dest-bits (scag d ((list @) bits))
:: left-shift the "missing" number of bits
=/ num=@
%: lsh 0
(sub d (lent dest-bits))
(rep 0 (flop dest-bits))
==
$(ret (snoc ret num), bits (slag d ((list @) bits)))
:: Converts e.g. ~[0 0 31 31 31 31 0 0] in base32 (5 bitwidth)
:: to ~[0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0]
::
++ from-digits
|= [bitwidth=@ digits=(list @)]
^- (list @)
%- zing
%+ turn digits
|= d=@ (zeros-brip bitwidth d)
:: converts 40 bits: ~[0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0]
:: to 0x3fff.fc00 when cast to hex
::
++ to-atom
|= bits=(list @)
^- @
%+ rep 0
%- flop bits
--
::
++ bech32
|%
++ prefixes
^- (map network tape)
(my [[%main "bc"] [%testnet "tb"] ~])
++ charset "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
+$ raw-decoded [hrp=tape data=(list @) checksum=(list @)]
::
++ 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=@ b=@] =(a b))
1
%- 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 @)]
^- bech32-address
=/ combined=(list @)
(weld data (checksum hrp data))
:- %bech32
%- crip
(zing ~[hrp "1" (tape (murn combined value-to-charset))])
++ decode-raw
|= b=bech32-address
^- (unit raw-decoded)
=/ bech (cass (trip +.b)) :: 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)]
:: goes from a bech32 address to hex. Returns byts to preserve leading 0s
::
++ to-hex
|= b=bech32-address ^- hash
=/ d=(unit raw-decoded) (decode-raw b)
?~ d ~|("Invalid bech32 address" !!)
=/ bs=(list @)
(from-digits:bits 5 (slag 1 data.u.d))
=/ byt-len=@ (div (lent bs) 8)
?. =(0 (mod (lent bs) 8))
~|("Invalid bech32 address: not 8bit" !!)
?. ?|(?=(%20 byt-len) ?=(%32 byt-len))
~|("Invalid bech32 address: must be 20 (P2WPKH) or 32 (P2WSH) bytes" !!)
%- hash
[byt-len (to-atom:bits bs)]
:: pubkey is the 33 byte ECC compressed public key
::
++ encode-pubkey
|= [=network pubkey=@ux]
^- (unit bech32-address)
?. =(33 (met 3 pubkey))
~|('pubkey must be a 33 byte ECC compressed public key' !!)
=/ prefix (~(get by prefixes) network)
?~ prefix ~
:- ~
%+ encode-raw u.prefix
[0 (convert:bits 5 (zeros-brip:bits 160 dat:(hash-160 pubkey)))]
++ encode-hash-160
|= [=network h160=byts]
^- (unit bech32-address)
=/ prefix (~(get by prefixes) network)
?~ prefix ~
:- ~
%+ encode-raw u.prefix
[0 (convert:bits 5 (zeros-brip:bits 160 dat.h160))]
--
::
--