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}