fp/main.go

package main

import (
	"bufio"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"os"
	"strings"

	"golang.org/x/crypto/ssh"
)

func main() {
	s := bufio.NewScanner(os.Stdin)
	for s.Scan() {
		pk, comment, _, _, err := ssh.ParseAuthorizedKey(s.Bytes())
		if err != nil {
			fmt.Fprintf(os.Stderr, "problem parsing pubkey from line %q: %v\n", s.Text(), err)
			continue
		}
		hsh := sha256.New()
		hsh.Write(pk.Marshal())
		chk := hsh.Sum(nil)
		var name string
		u := strings.Fields(comment)
		if len(u) > 0 {
			name = strings.Join(u[0:], " ")
		}
		fmt.Printf("%20s : %s (%s)\n", name, base64.StdEncoding.WithPadding(base64.NoPadding).EncodeToString(chk), pk.Type())

	}
	if err := s.Err(); err != nil {
		fmt.Fprintf(os.Stderr, "problem during scanning stdin: %v\n", err)
		os.Exit(1)
	}
}