Compute the hash of a TLS certificate

tls-cert-hash.go

package main

import (
	"crypto/sha256"
	"crypto/x509"
	"fmt"
	"io/ioutil"
)

func main() {
	dat, err := ioutil.ReadFile("/tmp/cert.der")
	if err != nil {
		panic(err)
	}
	certs, err := x509.ParseCertificates(dat)
	if err != nil {
		panic(err)
	}
	for _, cert := range certs {
		h := sha256.Sum256(cert.RawTBSCertificate)
		fmt.Printf("[%v]: %v\n", cert.Subject, fmt.Sprintf("%x", h))
	}
}