Script templates: add witness commitment template

src/templates/index.js

@@ -6,6 +6,8 @@ var pubKeyHash = require('./pubkeyhash')
 var scriptHash = require('./scripthash')
 var witnessPubKeyHash = require('./witnesspubkeyhash')
 var witnessScriptHash = require('./witnessscripthash')
+var witnessCommitment = require('./witnesscommitment')
+
 var types = {
   MULTISIG: 'multisig',
   NONSTANDARD: 'nonstandard',
@@ -14,7 +16,8 @@ var types = {
   P2PKH: 'pubkeyhash',
   P2SH: 'scripthash',
   P2WPKH: 'witnesspubkeyhash',
-  P2WSH: 'witnessscripthash'
+  P2WSH: 'witnessscripthash',
+  WITNESS_COMMITMENT: 'witnesscommitment'
 }
 
 function classifyOutput (script) {
@@ -27,6 +30,7 @@ function classifyOutput (script) {
   var chunks = decompile(script)
   if (multisig.output.check(chunks)) return types.MULTISIG
   if (pubKey.output.check(chunks)) return types.P2PK
+  if (witnessCommitment.output.check(chunks)) return types.WITNESS_COMMITMENT
   if (nullData.output.check(chunks)) return types.NULLDATA
 
   return types.NONSTANDARD
@@ -65,5 +69,6 @@ module.exports = {
   scriptHash: scriptHash,
   witnessPubKeyHash: witnessPubKeyHash,
   witnessScriptHash: witnessScriptHash,
+  witnessCommitment: witnessCommitment,
   types: types
 }

src/templates/witnesscommitment/index.js

@@ -0,0 +1,3 @@
+module.exports = {
+  output: require('./output')
+}

src/templates/witnesscommitment/output.js

@@ -0,0 +1,36 @@
+// OP_RETURN 36bytes:[0xaa21a9ed, Hash256(witnessRoot )]
+
+var bscript = require('../../script')
+var types = require('../../types')
+var typeforce = require('typeforce')
+var OPS = require('bitcoin-ops')
+
+function check (script) {
+  var buffer = bscript.compile(script)
+
+  return buffer.length > 37 &&
+    buffer[0] === OPS.OP_RETURN &&
+    buffer[1] === 0x24 &&
+    buffer.slice(2, 6).toString('hex') === 'aa21a9ed'
+}
+
+check.toJSON = function () { return 'Witness commitment output' }
+
+function encode (commitment) {
+  // hash256 0x21 hash160 0xed
+  typeforce(types.Hash256bit, commitment)
+
+  return bscript.compile([OPS.OP_RETURN, new Buffer('aa21a9ed' + commitment.toString('hex'), 'hex')])
+}
+
+function decode (buffer) {
+  typeforce(check, buffer)
+
+  return bscript.decompile(buffer)[1].slice(4, 36)
+}
+
+module.exports = {
+  check: check,
+  decode: decode,
+  encode: encode
+}