1 /**
2 * Portions of this software was developed by employees of the National Institute
3 * of Standards and Technology (NIST), an agency of the Federal Government and is
4 * being made available as a public service. Pursuant to title 17 United States
5 * Code Section 105, works of NIST employees are not subject to copyright
6 * protection in the United States. This software may be subject to foreign
7 * copyright. Permission in the United States and in foreign countries, to the
8 * extent that NIST may hold copyright, to use, copy, modify, create derivative
9 * works, and distribute this software and its documentation without fee is hereby
10 * granted on a non-exclusive basis, provided that this notice and disclaimer
11 * of warranty appears in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
14 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
15 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
17 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
18 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
19 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
20 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
21 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
22 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
23 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
24 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
25 */
26
27 package gov.nist.secauto.swid.client.totp;
28
29 import gov.nist.secauto.swid.client.totp.Hotp.HashAlgorithm;
30
31 import java.util.Calendar;
32 import java.util.GregorianCalendar;
33 import java.util.TimeZone;
34
35 /**
36 * A direct implementation of https://tools.ietf.org/html/rfc6238.
37 *
38 */
39 public class Totp {
40 // the size of the time step in seconds
41 private int timeStepSeconds;
42 // the time adjustment from UNIX time in seconds (based on UTC and the
43 // epoch)
44 private long T0;
45 // the internal HOTP implementation
46 private Hotp hotp;
47
48 /**
49 * Creates a default Totp instance with a 30 second time step, T0 of 0 using HMAC-SHA-1 producing an
50 * 8 digit output.
51 */
52 public Totp() {
53 this(30, 0L, HashAlgorithm.SHA1, 8);
54 }
55
56 /**
57 * Creates a Totp instance with a 30 second time step, T0 of 0 using the provided parameters.
58 *
59 * @param algorithm
60 * the algorithm to use
61 * @param digits
62 * the number of digits
63 */
64 public Totp(HashAlgorithm algorithm, int digits) {
65 this(30, 0L, algorithm, digits);
66 }
67
68 /**
69 * Creates a Totp instance with a 30 second time step, T0 of 0 using the provided parameters.
70 *
71 * @param timeStepSeconds
72 * the size of the time step in seconds (this is X in the RFC)
73 * @param algorithm
74 * the algorithm to use
75 * @param T0
76 * the time adjustment from UNIX time in seconds (based on UTC and the epoch)
77 * @param digits
78 * the number of digits
79 * @see Hotp
80 */
81 public Totp(int timeStepSeconds, long T0, HashAlgorithm algorithm, int digits) {
82 if (timeStepSeconds <= 0) {
83 throw new IllegalArgumentException("timeStepSeconds must be greater than zero");
84 }
85 this.timeStepSeconds = timeStepSeconds;
86 this.T0 = T0;
87 this.hotp = new Hotp(algorithm, digits);
88 }
89
90 /**
91 * Calculates a TOTP result using the provided key and the current time
92 *
93 * @param key
94 * the key/seed to use for calculating the value
95 * @return the TOTP value for the current time point
96 */
97 public String totp(byte[] key) {
98 return totp(key, currentTime());
99 }
100
101 /**
102 * Calculates a TOTP result using the provided key and provided time
103 *
104 * @param key
105 * the key/seed to use for calculating the value
106 * @param time
107 * the time value to use
108 * @return the TOTP value for the provided time point
109 */
110 public String totp(byte[] key, long time) {
111 long T = (time - T0) / timeStepSeconds;
112 return hotp.generate(key, T);
113 }
114
115 /**
116 * @return the current UNIX time (based on UTC and epoch) in seconds
117 */
118 private long currentTime() {
119 Calendar calendar = GregorianCalendar.getInstance(TimeZone.getTimeZone("UTC"));
120 return calendar.getTimeInMillis() / 1000;
121 }
122 }