package main

import (
    "fmt"
    "log"

    "github.com/ethereum/go-ethereum/common/hexutil"
    "github.com/ethereum/go-ethereum/crypto"
)

func main() {
    privateKey, err := crypto.HexToECDSA("fad9c8855b740a0b7ed4c221dbad0f33a83a49cad6b3fe8d5817ac83d38b6a19")
    if err != nil {
        log.Fatal(err)
    }

    data := []byte("decartography")
    hash := crypto.Keccak256Hash(data)
    fmt.Println(hash.Hex()) // 0xfe2b8f0bae0d344e95a421b9cc1a32ef07083cc85d007146259221fece9264a7

    signature, err := crypto.Sign(hash.Bytes(), privateKey)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(hexutil.Encode(signature))
}