Line	Hits	Note	Source
1			/*
2			* $Id: LuhnAlgorithm.java 1011 2008-06-16 17:57:36Z amandel $
3			*
4			* Copyright 2006, The jCoderZ.org Project. All rights reserved.
5			*
6			* Redistribution and use in source and binary forms, with or without
7			* modification, are permitted provided that the following conditions are
8			* met:
9			*
10			* * Redistributions of source code must retain the above copyright
11			* notice, this list of conditions and the following disclaimer.
12			* * Redistributions in binary form must reproduce the above
13			* copyright notice, this list of conditions and the following
14			* disclaimer in the documentation and/or other materials
15			* provided with the distribution.
16			* * Neither the name of the jCoderZ.org Project nor the names of
17			* its contributors may be used to endorse or promote products
18			* derived from this software without specific prior written
19			* permission.
20			*
21			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
22			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24			* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS
25			* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26			* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27			* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
28			* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29			* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30			* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
31			* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32			*/
33			package org.jcoderz.commons.util;
34
35			import org.jcoderz.commons.ArgumentMalformedException;
36
37			/**
38			* The Luhn algorithm.
39			*
40			* The Luhn algorithm or Luhn formula, also known as the
41			* <b>modulus 10</b> or <b>mod 10</b> algorithm, was developed
42			* in the 1960s as a method of validating identification numbers.
43			* It is a simple checksum formula used to validate a variety
44			* of account numbers, such as credit card numbers and Canadian
45			* Social Insurance Numbers.
46			* Much of its notoriety comes from credit card companies' adoption
47			* of it shortly after its creation in the late 1960s by
48			* IBM scientist Hans Peter Luhn (1896-1964).
49			*
50			* The algorithm is in the public domain and is in wide use today.
51			* It is not intended to be a cryptographically secure hash function;
52			* it protects against random error, not malicious attack.
53			* Most credit cards and many government identification numbers
54			* use the algorithm as a simple method of distinguishing valid
55			* numbers from collections of random digits.
56			*
57			* @author Michael Griffel
58			*/
59			public final class LuhnAlgorithm
60			{
61			private static final int MAX_DIGIT = 9;
62			private static final int MODULUS = 10;
63
64			/**
65			* Private Constructor.
66			*/
67			private LuhnAlgorithm ()
68	0		{
69			// provides only static methods - no instances allowed.
70	0		}
71
72			/**
73			* Execute the Luhn (Mod10) card check on a given card number.
74			*
75			* @param cardNumber the card number to check.
76			* @return <tt>true</tt> if the Luhn check succeeds;
77			* <tt>false</tt> otherwise.
78			*/
79			public static boolean check (String cardNumber)
80			{
81	0		final String s = reverseString(cardNumber);
82	0		int crossSum = 0;
83	0		for (int i = 0; i < s.length(); i++)
84			{
85	0		final int digit = s.charAt(i) - '0';
86
87	0		if (isOdd(i))
88			{
89	0		crossSum += computeCrossSum(digit);
90			}
91			else
92			{
93	0		crossSum += digit;
94			}
95			}
96
97	0		return (crossSum % MODULUS == 0);
98			}
99
100			/**
101			* Computes the Luhn check digit for a given card number.
102			*
103			* @param cardNumberWithoutLastDigit the card number without
104			* the last digit.
105			* @return the Luhn check digit for the given card number.
106			*/
107			public static int computeLuhnCardNumber (String cardNumberWithoutLastDigit)
108			{
109	0		final String s = reverseString(cardNumberWithoutLastDigit);
110
111	0		int crossSum = 0;
112	0		for (int i = 0; i < s.length(); i++)
113			{
114	0		final int digit = s.charAt(i) - '0';
115	0		if (isEven(i))
116			{
117	0		crossSum += computeCrossSum(digit);
118			}
119			else
120			{
121	0		crossSum += digit;
122			}
123			}
124	0		crossSum %= MODULUS;
125
126	0		return (MODULUS - crossSum) % MODULUS;
127			}
128
129
130			private static boolean isEven (int i)
131			{
132	0		return (i & 1) == 0;
133			}
134
135			private static boolean isOdd (int i)
136			{
137	0		return (i & 1) == 1;
138			}
139
140			private static int computeCrossSum (int number)
141			{
142	0		if (number > MAX_DIGIT)
143			{
144	0	(1)	throw new ArgumentMalformedException("number",
145			String.valueOf(number), "Number must be between 0 and 9");
146			}
147	0		final int i = number << 1;
148	0		return (i > MAX_DIGIT ? i - MAX_DIGIT : i);
149			}
150
151			private static String reverseString (String s)
152			{
153	0		final char[] source = s.toCharArray();
154	0		final char[] reversed = new char[source.length];
155	0		for (int i = 0; i < reversed.length; i++)
156			{
157	0		reversed[i] = source[reversed.length - i - 1];
158			}
159	0		return String.valueOf(reversed);
160			}
161			}

Findings in this File

(1)

144

method org.jcoderz.commons.util.LuhnAlgorithm.computeCrossSum(int) throws exception with static message string

Project Report: fawkez

Packagesummary org.jcoderz.commons.util

org.jcoderz.commons.util.LuhnAlgorithm

Findings in this File