001// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
002//
003// SPDX-License-Identifier: Apache-2.0
004
005package org.pgpainless.key.util;
006
007import java.math.BigInteger;
008import java.util.regex.Pattern;
009
010public final class KeyIdUtil {
011
012    private KeyIdUtil() {
013
014    }
015
016    private static final Pattern LONG_KEY_ID = Pattern.compile("^[0-9A-Fa-f]{16}$");
017
018    /**
019     * Convert a long key-id into a key-id.
020     * A long key-id is a 16 digit hex string.
021     *
022     * @param longKeyId 16-digit hexadecimal string
023     * @return key-id converted to {@link Long}.
024     */
025    public static long fromLongKeyId(String longKeyId) {
026        if (!LONG_KEY_ID.matcher(longKeyId).matches()) {
027            throw new IllegalArgumentException("Provided long key-id does not match expected format. " +
028                    "A long key-id consists of 16 hexadecimal characters.");
029        }
030
031        return new BigInteger(longKeyId, 16).longValue();
032    }
033}