feat: block verification functions

Copy the block verification functions from
https://github.com/cardano-foundation/cardano-ibc-incubator with minimal
modifications.

Signed-off-by: Chris Gianelloni <[email protected]>

ledger/verify_block.go

@@ -0,0 +1,114 @@
+// Copyright 2024 Cardano Foundation
+// Copyright 2024 Blink Labs Software
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This file is taken almost verbatim (including comments) from
+// https://github.com/cardano-foundation/cardano-ibc-incubator
+
+package ledger
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+
+	"github.com/blinklabs-io/gouroboros/cbor"
+)
+
+func VerifyBlock(block BlockHexCbor) (error, bool, string, uint64, uint64) {
+	headerCborHex := block.HeaderCbor
+	epochNonceHex := block.Eta0
+	bodyHex := block.BlockBodyCbor
+	slotPerKesPeriod := uint64(block.Spk)
+
+	isValid := false
+	vrfHex := ""
+
+	// check is KES valid
+	headerCborByte, headerDecodeError := hex.DecodeString(headerCborHex)
+	if headerDecodeError != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: headerCborByte decode error, %v", headerDecodeError.Error())), false, "", 0, 0
+	}
+	header, headerUnmarshalError := NewBabbageBlockHeaderFromCbor(headerCborByte)
+	if headerUnmarshalError != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: header unmarshall error, %v", headerUnmarshalError.Error())), false, "", 0, 0
+	}
+	isKesValid, errKes := VerifyKes(header, slotPerKesPeriod)
+	if errKes != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: kes invalid, %v", errKes.Error())), false, "", 0, 0
+	}
+
+	// check is VRF valid
+	// Ref: https://github.com/IntersectMBO/ouroboros-consensus/blob/de74882102236fdc4dd25aaa2552e8b3e208448c/ouroboros-consensus-protocol/src/ouroboros-consensus-protocol/Ouroboros/Consensus/Protocol/Praos.hs#L541
+	epochNonceByte, epochNonceDecodeError := hex.DecodeString(epochNonceHex)
+	if epochNonceDecodeError != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: epochNonceByte decode error, %v", epochNonceDecodeError.Error())), false, "", 0, 0
+	}
+	vrfBytes := header.Body.VrfKey[:]
+	vrfResult := header.Body.VrfResult.([]interface{})
+	vrfProofBytes := vrfResult[1].([]byte)
+	vrfOutputBytes := vrfResult[0].([]byte)
+	seed := MkInputVrf(int64(header.Body.Slot), epochNonceByte)
+	output, errVrf := VrfVerifyAndHash(vrfBytes, vrfProofBytes, seed)
+	if errVrf != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: vrf invalid, %v", errVrf.Error())), false, "", 0, 0
+	}
+	isVrfValid := bytes.Equal(output, vrfOutputBytes)
+
+	// check if block data valid
+	blockBodyHash := header.Body.BlockBodyHash
+	blockBodyHashHex := hex.EncodeToString(blockBodyHash[:])
+	isBodyValid, isBodyValidError := VerifyBlockBody(bodyHex, blockBodyHashHex)
+	if isBodyValidError != nil {
+		return errors.New(fmt.Sprintf("VerifyBlock: VerifyBlockBody error, %v", isBodyValidError.Error())), false, "", 0, 0
+	}
+	isValid = isKesValid && isVrfValid && isBodyValid
+	vrfHex = hex.EncodeToString(vrfBytes)
+	blockNo := header.Body.BlockNumber
+	slotNo := header.Body.Slot
+	return nil, isValid, vrfHex, blockNo, slotNo
+}
+
+func ExtractBlockData(bodyHex string) ([]UTXOOutput, []RegisCert, []DeRegisCert, error) {
+	rawDataBytes, rawDataBytesError := hex.DecodeString(bodyHex)
+	if rawDataBytesError != nil {
+		return nil, nil, nil, errors.New(fmt.Sprintf("ExtractBlockData: bodyHex decode error, %v", rawDataBytesError.Error()))
+	}
+	var txsRaw [][]string
+	_, err := cbor.Decode(rawDataBytes, &txsRaw)
+	if err != nil {
+		return nil, nil, nil, errors.New(fmt.Sprintf("ExtractBlockData: txsRaw decode error, %v", err.Error()))
+	}
+	txBodies, txBodiesError := GetTxBodies(txsRaw)
+	if err != nil {
+		return nil, nil, nil, errors.New(fmt.Sprintf("ExtractBlockData: GetTxBodies error, %v", txBodiesError.Error()))
+	}
+	uTXOOutput, regisCerts, deRegisCerts, getBlockOutputError := GetBlockOutput(txBodies)
+	if getBlockOutputError != nil {
+		return nil, nil, nil, errors.New(fmt.Sprintf("ExtractBlockData: GetBlockOutput error, %v", getBlockOutputError.Error()))
+	}
+	return uTXOOutput, regisCerts, deRegisCerts, nil
+}
+
+// These are copied from types.go
+
+type BlockHexCbor struct {
+	_             struct{} `cbor:",toarray"`
+	Flag          int
+	HeaderCbor    string
+	Eta0          string
+	Spk           int
+	BlockBodyCbor string
+}