From efdcdf0fdc56673aeab114f0ec8fa100b98eaa0b Mon Sep 17 00:00:00 2001
From: timlucmiptev <info@timlucmiptev.space>
Date: Fri, 16 Oct 2020 14:32:48 +0300
Subject: [PATCH] sighash-witness works

---
 bippy-scratch.md |  5 ++++-
 lib/btc.hoon     | 30 +++++++++++++++++++++++++++---
 sur/btc.hoon     |  5 ++++-
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/bippy-scratch.md b/bippy-scratch.md
index 79fdf0c759..ddb19ead5b 100644
--- a/bippy-scratch.md
+++ b/bippy-scratch.md
@@ -191,7 +191,10 @@ Native P2WPKH
 
 =output0 (output:tx:btcs [[%bech32 'bc1qs2qtxl0n0rdenan0shy457p6w6k85m2e36f7ze'] 112.340.000])
 =output1 (output:tx:btcs [[%bech32 'bc1q800y9klw0exmu63pkt2sechszel64q2enddkt4'] 223.450.000])
-=utx (unsigned:tx:btcs [~[input0 input1] ~[output0 output1]])
+=utx (unsigned:tx:btcs [1 0x11 ~[input0 input1] ~[output0 output1]])
+
+(~(sighash unsigned-tx:btc utx) 1)
+:: gives [wid=32 dat=0xc37a.f311.16d1.b27c.af68.aae9.e3ac.82f1.4779.2901.4d5b.9176.57d0.eb49.478c.b670]
 ```
 
 ## cutting off the last 20 bytes (for bech32 address outputs):
diff --git a/lib/btc.hoon b/lib/btc.hoon
index 23187e9bc3..9ffc960d29 100644
--- a/lib/btc.hoon
+++ b/lib/btc.hoon
@@ -104,15 +104,39 @@
       (turn inputs.ut sequence-buffer)
     =/  outputs=byts
       %-  concat-as-byts  (turn outputs.ut outputs-buffer)
-    ::  all the variables
+    ::  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)
-    ~&  >  [prevouts=(dsha256 prevouts) sequences=(dsha256 sequences) outputs=(dsha256 outputs)]
-    [0 0x0]
+    =/  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
+    ==
   ::
   ++  sighash-legacy
     |=  =input:tx  ^-  hash
diff --git a/sur/btc.hoon b/sur/btc.hoon
index c6a77a32c2..4aff779c41 100644
--- a/sur/btc.hoon
+++ b/sur/btc.hoon
@@ -9,7 +9,9 @@
 ++  tx
   |%
   +$  unsigned
-    $:  inputs=(list input)
+    $:  version=@
+        locktime=@
+        inputs=(list input)
         outputs=(list output)
     ==
   +$  input
@@ -35,3 +37,4 @@
   ++  op-checksig     172
   --
 --
+