#!/bin/bash

KEY=$1
PASS=$2

declare -a ARGS
if [[ -n "$KEY" ]]; then
    if [[ ! -r "$KEY" ]]; then
        echo "Usage: $0 [KEY [PASSFILE]]" >&2
        exit 1
    fi

    ARGS+=("-in" "$KEY")
fi

if [[ -n "$PASS" ]]; then
    if [[ ! -r "$PASS" ]]; then
        echo "Usage: $0 [KEY [PASSFILE]]" >&2
        exit 1
    fi

    ARGS+=("-passin" "file:$PASS")
fi

openssl rsa "${ARGS[@]}" -pubout 2>/dev/null | \
    openssl rsa -pubin -noout -text | \
    sed -e '/Modulus:$/d;s/Public-Key: (\(.*\))/Modulus (\1):/'