Change serial number from bytes to string

[oliveromahony]

Proposed changes

Report the serial number as a string, helps with serialisation / deserialisation

Note: the below example uses built in encoding/json but for protos then google.golang.org/protobuf/encoding/protojson is recommended.

package main

import (
	"crypto/rand"
	"encoding/json"
	"fmt"
	"math/big"
)

func main() {
	// Step 1: Generate a big integer (or use your own big.Int)
	limit := new(big.Int).Lsh(big.NewInt(1), 63)      // 1 << 63
	originalBigInt, _ := rand.Int(rand.Reader, limit) // Random big integer less than 1 << 63
	fmt.Println("Original BigInt:", originalBigInt)

	// Step 2: Encode the text representation to JSON
	jsonData, err := json.Marshal(originalBigInt.String())
	if err != nil {
		panic(err)
	}
	fmt.Println("JSON Encoded Data:", string(jsonData))

	// Step 3: Decode JSON back to the text representation
	var decodedText string
	if err := json.Unmarshal(jsonData, &decodedText); err != nil {
		panic(err)
	}
	fmt.Println("Decoded Text:", decodedText)

	// Verify correctness
	if decodedText == originalBigInt.String() {
		fmt.Println("Values match!")
	}
}

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13