authkeys-report.sh

#!/bin/sh
# original src: https://unix.stackexchange.com/a/2146/17806

# usage: authkeys-report <authorized_keys-file>    

set -ue

tmp="$(mktemp -t fingerprint-authkeys.XXXXXXXX)"
trap 'rm -f "$tmp"' 0

while read opts key; do
    case "$opts" in
        [0-9]*|ssh-dss|ssh-rsa|ssh-ed25519)
            # not options, first "word" is part of key
            key="$opts $key"
        ;;
    esac
    echo "$key" >$tmp
    set -- $(ssh-keygen -lf "$tmp")
    bits="$1" fingerprint="$2"

    set -- $key # Note: will mangle whitespace in the comment
    case "$1" in
        [0-9]*) # SSH v1 key
            type=rsa1
            shift 3
        ;;
        ssh-rsa|ssh-dss|ssh-ed25519) # SSH v2 key
            type="$1"
            shift 2
        ;;
        *)
            type=unknown
            set --
        ;;
    esac

    printf '%-14s %-9s %s %s\n' "$type" "$bits" "$fingerprint" "$*"
done <$1