Getting the fingerprint of a certificate in Go

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If you need to get the fingerprint for a given certificate, we can use OpenSSL to do it, but we may also want to do the same in Go.

We can adapt this StackOverflow answer and this blog post to produce the following:

package main

import (

func fingerprint(address string) string {
	conf := &tls.Config{
		InsecureSkipVerify: true, // as it may be self-signed

	conn, err := tls.Dial("tcp", address, conf)
	if err != nil {
		log.Println("Error in Dial", err)
		return ""
	defer conn.Close()
	cert := conn.ConnectionState().PeerCertificates[0]
	fingerprint := sha1.Sum(cert.Raw)
	return fmt.Sprintf("%x", fingerprint) // to make sure it's a hex string

func main() {

Written by Jamie Tanna's profile image Jamie Tanna on , and last updated on .

Content for this article is shared under the terms of the Creative Commons Attribution Non Commercial Share Alike 4.0 International, and code is shared under the Apache License 2.0.

#blogumentation #go #certificates.

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