    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.validator.routines.checkdigit;
    018
    019import java.io.Serializable;
    020
    021/**
    022 * <b>IBAN</b> (International Bank Account Number) Check Digit calculation/validation.
    023 * <p>
    024 * This routine is based on the ISO 7064 Mod 97,10 check digit calculation routine.
    025 * <p>
    026 * The two check digit characters in a IBAN number are the third and fourth characters
    027 * in the code. For <i>check digit</i> calculation/validation the first four characters are moved
    028 * to the end of the code.
    029 *  So <code>CCDDnnnnnnn</code> becomes <code>nnnnnnnCCDD</code> (where
    030 *  <code>CC</code> is the country code and <code>DD</code> is the check digit). For
    031 *  check digit calculation the check digit value should be set to zero (i.e.
    032 *  <code>CC00nnnnnnn</code> in this example.
    033 * <p>
    034 * Note: the class does not check the format of the IBAN number, only the check digits.
    035 * <p>
    036 * For further information see
    037 *  <a href="http://en.wikipedia.org/wiki/International_Bank_Account_Number">Wikipedia -
    038 *  IBAN number</a>.
    039 *
    040 * @version $Revision$
    041 * @since Validator 1.4
    042 */
    043public final class IBANCheckDigit implements CheckDigit, Serializable {
    044
    045    private static final int MIN_CODE_LEN = 5;
    046
    047    private static final long serialVersionUID = -3600191725934382801L;
    048
    049    private static final int MAX_ALPHANUMERIC_VALUE = 35; // Character.getNumericValue('Z')
    050
    051    /** Singleton IBAN Number Check Digit instance */
    052    public static final CheckDigit IBAN_CHECK_DIGIT = new IBANCheckDigit();
    053
    054    private static final long MAX = 999999999;
    055
    056    private static final long MODULUS = 97;
    057
    058    /**
    059     * Construct Check Digit routine for IBAN Numbers.
    060     */
    061    public IBANCheckDigit() {
    062    }
    063
    064    /**
    065     * Validate the check digit of an IBAN code.
    066     *
    067     * @param code The code to validate
    068     * @return <code>true</code> if the check digit is valid, otherwise
    069     * <code>false</code>
    070     */
    071    @Override
    072    public boolean isValid(String code) {
    073        if (code == null || code.length() < MIN_CODE_LEN) {
    074            return false;
    075        }
    076        String check = code.substring(2,4); // CHECKSTYLE IGNORE MagicNumber
    077        if ("00".equals(check) || "01".equals(check) || "99".equals(check)) {
    078            return false;
    079        }
    080        try {
    081            int modulusResult = calculateModulus(code);
    082            return (modulusResult == 1);
    083        } catch (CheckDigitException  ex) {
    084            return false;
    085        }
    086    }
    087
    088    /**
    089     * Calculate the <i>Check Digit</i> for an IBAN code.
    090     * <p>
    091     * <b>Note:</b> The check digit is the third and fourth
    092     * characters and is set to the value "<code>00</code>".
    093     *
    094     * @param code The code to calculate the Check Digit for
    095     * @return The calculated Check Digit as 2 numeric decimal characters, e.g. "42"
    096     * @throws CheckDigitException if an error occurs calculating
    097     * the check digit for the specified code
    098     */
    099    @Override
    100    public String calculate(String code) throws CheckDigitException {
    101        if (code == null || code.length() < MIN_CODE_LEN) {
    102            throw new CheckDigitException("Invalid Code length=" +
    103                    (code == null ? 0 : code.length()));
    104        }
    105        code = code.substring(0, 2) + "00" + code.substring(4); // CHECKSTYLE IGNORE MagicNumber
    106        int modulusResult = calculateModulus(code);
    107        int charValue = (98 - modulusResult); // CHECKSTYLE IGNORE MagicNumber
    108        String checkDigit = Integer.toString(charValue);
    109        return (charValue > 9 ? checkDigit : "0" + checkDigit); // CHECKSTYLE IGNORE MagicNumber
    110    }
    111
    112    /**
    113     * Calculate the modulus for a code.
    114     *
    115     * @param code The code to calculate the modulus for.
    116     * @return The modulus value
    117     * @throws CheckDigitException if an error occurs calculating the modulus
    118     * for the specified code
    119     */
    120    private int calculateModulus(String code) throws CheckDigitException {
    121        String reformattedCode = code.substring(4) + code.substring(0, 4); // CHECKSTYLE IGNORE MagicNumber
    122        long total = 0;
    123        for (int i = 0; i < reformattedCode.length(); i++) {
    124            int charValue = Character.getNumericValue(reformattedCode.charAt(i));
    125            if (charValue < 0 || charValue > MAX_ALPHANUMERIC_VALUE) {
    126                throw new CheckDigitException("Invalid Character[" +
    127                        i + "] = '" + charValue + "'");
    128            }
    129            total = (charValue > 9 ? total * 100 : total * 10) + charValue; // CHECKSTYLE IGNORE MagicNumber
    130            if (total > MAX) {
    131                total = total % MODULUS;
    132            }
    133        }
    134        return (int)(total % MODULUS);
    135    }
    136
    137}