Verify witness_signature of a block header of Tron block

README.md

Block header of Tron block number 200 is

{
	"blockID": "00000000000000c82a54a3bbdc956e1ddebc903f29b8daf28505b56f55a3f87d",
	"block_header": {
		"raw_data": {
			"number": 200,
			"txTrieRoot": "0000000000000000000000000000000000000000000000000000000000000000",
			"witness_address": "411661f25387370c9cd3a9a5d97e60ca90f4844e7e",
			"parentHash": "00000000000000c7c8f27726916dfddca3c1c3481eb01da8a08938263674cea4",
			"timestamp": 1529892138000
		},
		"witness_signature": "691e9116963b54ef7eb07692266319b029217e4d4ae8e8cb97e341617460f3822eff149c690aac6f2e0ad27d0af4fa8824d113d7a71c091245f778438ca4bde801"
	}
}

If you want to verify the signature in Solidity first run the main.go, which serialize block header and finds its raw hash. Then copy the result from the go program and make a call to contract to validate function with parameters hash=raw hash from go program ,signature is the same as witness_signature and witness_address is the same as in block header but without the first two bytes(41) because this is not part of address(it only tells which network). In Remix ide you can call with these parameters: 0x9df34ad7b14739e82a54a3bbdc956e1ddebc903f29b8daf28505b56f55a3f87d, 0x691e9116963b54ef7eb07692266319b029217e4d4ae8e8cb97e341617460f3822eff149c690aac6f2e0ad27d0af4fa8824d113d7a71c091245f778438ca4bde801, 0x1661f25387370c9cd3a9a5d97e60ca90f4844e7e

main.go

package main

import (
	"crypto/sha256"
	"fmt"
	"log"

	"github.com/tronprotocol/tron-demo/demo/go-client-api/common/hexutil"

	"github.com/gogo/protobuf/proto"

	"github.com/sasaxie/go-client-api/service"
)

func main() {
	// connect to some grpc client
	client := service.NewGrpcClient("grpc.trongrid.io:50051")
	client.Start()
	defer client.Conn.Close()

	block := client.GetBlockByNum(200)
	// serialize block header
	b, err := proto.Marshal(block.BlockHeader.RawData)
	if err != nil {
		log.Fatal(err)
	}
	// hash the raw data
	hash := sha256.Sum256(b[:])
	// hex encode 
	fmt.Printf("block hash: %v\n", hexutil.Encode(hash[:]))
}

verify.sol

pragma solidity >=0.4.24 <0.7.0;

contract VerifyTronSignature {
    //return the address according to the signature and and the data
    function validate(bytes32 hash, bytes memory signature, address witness_addr) public {
        bytes memory signedString = signature;
        bytes32  r = convertToBytes32(slice(signedString, 0, 32));
        bytes32  s = convertToBytes32(slice(signedString, 32, 32));
        byte  v1 = slice(signedString, 64, 1)[0];
        uint8 v = uint8(v1)+27;
        
       
        require(ecrecover(hash, v, r, s) == witness_addr);
    }
  
  
    
    //slice function
    function slice(bytes memory data, uint start, uint len) public returns (bytes memory){
        bytes memory b = new bytes(len);
        for(uint i = 0; i < len; i++){
            b[i] = data[i + start];
        }
        return b;
    }
    //convert bytes to bytes32
    function convertToBytes32(bytes memory source) public returns (bytes32 result) {
        assembly {
            result := mload(add(source, 32))
        }
    }
}