fix some typos and make OP_DATA_20 explicit in comment (#2080)

txscript/doc.go

@@ -17,7 +17,7 @@ bitcoin transaction scripts.
 Bitcoin transaction scripts are written in a stack-base, FORTH-like language.
 
 The bitcoin script language consists of a number of opcodes which fall into
-several categories such pushing and popping data to and from the stack,
+several categories such as pushing and popping data to and from the stack,
 performing basic and bitwise arithmetic, conditional branching, comparing
 hashes, and checking cryptographic signatures.  Scripts are processed from left
 to right and intentionally do not provide loops.

txscript/engine.go

@@ -605,7 +605,7 @@ func (vm *Engine) verifyWitnessProgram(witness wire.TxWitness) error {
 			return scriptError(ErrWitnessProgramWrongLength, errStr)
 		}
 
-	// We're attempting to to verify a taproot input, and the witness
+	// We're attempting to verify a taproot input, and the witness
 	// program data push is of the expected size, so we'll be looking for a
 	// normal key-path spend, or a merkle proof for a tapscript with
 	// execution afterwards.

txscript/script.go

@@ -178,7 +178,7 @@ func DisasmString(script []byte) (string, error) {
 // removeOpcodeRaw will return the script after removing any opcodes that match
 // `opcode`. If the opcode does not appear in script, the original script will
 // be returned unmodified. Otherwise, a new script will be allocated to contain
-// the filtered script. This metehod assumes that the script parses
+// the filtered script. This method assumes that the script parses
 // successfully.
 //
 // NOTE: This function is only valid for version 0 scripts.  Since the function

txscript/sigvalidate.go

@@ -385,7 +385,7 @@ func (t *taprootSigVerifier) Verify() bool {
 var _ signatureVerifier = (*taprootSigVerifier)(nil)
 
 // baseTapscriptSigVerifier verifies a signature for an input spending a
-// tapscript leaf from the prevoous output.
+// tapscript leaf from the previous output.
 type baseTapscriptSigVerifier struct {
 	*taprootSigVerifier
 

txscript/standard.go

@@ -153,7 +153,7 @@ func isPubKeyScript(script []byte) bool {
 // is a standard pay-to-pubkey-hash script.  It will return nil otherwise.
 func extractPubKeyHash(script []byte) []byte {
 	// A pay-to-pubkey-hash script is of the form:
-	//  OP_DUP OP_HASH160 <20-byte hash> OP_EQUALVERIFY OP_CHECKSIG
+	//  OP_DUP OP_HASH160 OP_DATA_20 <20-byte hash> OP_EQUALVERIFY OP_CHECKSIG
 	if len(script) == 25 &&
 		script[0] == OP_DUP &&
 		script[1] == OP_HASH160 &&
@@ -181,7 +181,7 @@ func isPubKeyHashScript(script []byte) bool {
 // versions.
 func extractScriptHash(script []byte) []byte {
 	// A pay-to-script-hash script is of the form:
-	//  OP_HASH160 <20-byte scripthash> OP_EQUAL
+	//  OP_HASH160 OP_DATA_20 <20-byte scripthash> OP_EQUAL
 	if len(script) == 23 &&
 		script[0] == OP_HASH160 &&
 		script[1] == OP_DATA_20 &&

txscript/taproot.go

@@ -65,7 +65,7 @@ func VerifyTaprootKeySpend(witnessProgram []byte, rawSig []byte, tx *wire.MsgTx,
 	// program.
 	rawKey := witnessProgram
 
-	// Extract the annex if it exists, so we can compute the proper proper
+	// Extract the annex if it exists, so we can compute the proper
 	// sighash below.
 	var annex []byte
 	witness := tx.TxIn[inputIndex].Witness