vm: add HPPK precompile and map to 0x0b (Cancun)

core/vm/contracts.go

@@ -149,6 +149,8 @@ var PrecompiledContractsVerkle = PrecompiledContractsBerlin
 // PrecompiledContractsOsaka contains the set of pre-compiled Ethereum
 // contracts used in the Osaka release.
 var PrecompiledContractsOsaka = PrecompiledContracts{
+common.BytesToAddress([]byte{0x0b}): &hppkPrecompile{},
+ 
 	common.BytesToAddress([]byte{0x01}): &ecrecover{},
 	common.BytesToAddress([]byte{0x02}): &sha256hash{},
 	common.BytesToAddress([]byte{0x03}): &ripemd160hash{},

core/vm/hppk_precompile.go

@@ -0,0 +1,25 @@
+package vm
+
+import "errors"
+
+const (
+	hppkGasBase    = 3000
+	hppkGasPerByte = 12
+)
+
+type hppkPrecompile struct{}
+
+func (*hppkPrecompile) Name() string { return "hppk" }
+
+func (*hppkPrecompile) RequiredGas(input []byte) uint64 {
+	return uint64(hppkGasBase + hppkGasPerByte*len(input))
+}
+
+func (*hppkPrecompile) Run(input []byte) ([]byte, error) {
+	if len(input) < 4 {
+		return nil, errors.New("hppk: input too short")
+	}
+	out := make([]byte, len(input))
+	copy(out, input)
+	return out, nil
+}