1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////
package com.google.crypto.tink.jwt;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.Immutable;
import java.security.GeneralSecurityException;
import java.util.Objects;
import java.util.Optional;
/** Describes the parameters of a {@code JwtHmacKey}. */
public class JwtHmacParameters extends JwtMacParameters {
/** Specifies how the "kid" header is handled. */
@Immutable
public static final class KidStrategy {
/**
* The "kid" is the URL safe (RFC 4648 Section 5) base64-encoded big-endian key_id in the
* keyset.
*
* <p>In {@code computeMacAndEncode} Tink always adds the KID.
*
* <p>In {@code verifyMacAndDecode} Tink checks that the kid is present and equal to this value.
*
* <p>This strategy is recommended by Tink.
*/
public static final KidStrategy BASE64_ENCODED_KEY_ID =
new KidStrategy("BASE64_ENCODED_KEY_ID");
/**
* The "kid" header is ignored.
*
* <p>In {@code computeMacAndEncode} Tink does not write a "kid" header.
*
* <p>In {@code verifyMacAndDecode} Tink ignores the "kid" header.
*/
public static final KidStrategy IGNORED = new KidStrategy("IGNORED");
/**
* The "kid" is fixed. It can be obtained from {@code parameters.getCustomKid()}.
*
* <p>In {@code computeMacAndEncode} Tink writes the "kid" header to the value given by {@code
* parameters.getCustomKid()}.
*
* <p>In {@code verifyMacAndDecode} If the kid is present, it needs to match {@code
* parameters.getCustomKid()}. If the kid is absent, it will be accepted.
*
* <p>Note: Tink does not allow to randomly generate new {@link JwtHmacKey} objects from
* parameters objects with {@code KidStrategy} equals to {@code CUSTOM}.
*/
public static final KidStrategy CUSTOM = new KidStrategy("CUSTOM");
private final String name;
private KidStrategy(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
/** The algorithm to be used for the mac computation. */
@Immutable
public static final class Algorithm {
public static final Algorithm HS256 = new Algorithm("HS256");
public static final Algorithm HS384 = new Algorithm("HS384");
public static final Algorithm HS512 = new Algorithm("HS512");
private final String name;
private Algorithm(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
public String getStandardName() {
return name;
}
}
/** Helps creating a {@code JwtHmacParameters} object. */
public static final class Builder {
Optional<Integer> keySizeBytes = Optional.empty();
Optional<KidStrategy> kidStrategy = Optional.empty();
Optional<Algorithm> algorithm = Optional.empty();
@CanIgnoreReturnValue
public Builder setKeySizeBytes(int keySizeBytes) {
this.keySizeBytes = Optional.of(keySizeBytes);
return this;
}
@CanIgnoreReturnValue
public Builder setKidStrategy(KidStrategy kidStrategy) {
this.kidStrategy = Optional.of(kidStrategy);
return this;
}
@CanIgnoreReturnValue
public Builder setAlgorithm(Algorithm algorithm) {
this.algorithm = Optional.of(algorithm);
return this;
}
public JwtHmacParameters build() throws GeneralSecurityException {
if (!keySizeBytes.isPresent()) {
throw new GeneralSecurityException("Key Size must be set");
}
if (!algorithm.isPresent()) {
throw new GeneralSecurityException("Algorithm must be set");
}
if (!kidStrategy.isPresent()) {
throw new GeneralSecurityException("KidStrategy must be set");
}
if (keySizeBytes.get() < 16) {
throw new GeneralSecurityException("Key size must be at least 16 bytes");
}
return new JwtHmacParameters(keySizeBytes.get(), kidStrategy.get(), algorithm.get());
}
private Builder() {}
}
public static Builder builder() {
return new Builder();
}
private JwtHmacParameters(int keySizeBytes, KidStrategy kidStrategy, Algorithm algorithm) {
this.keySizeBytes = keySizeBytes;
this.kidStrategy = kidStrategy;
this.algorithm = algorithm;
}
private final int keySizeBytes;
private final KidStrategy kidStrategy;
private final Algorithm algorithm;
public int getKeySizeBytes() {
return keySizeBytes;
}
public KidStrategy getKidStrategy() {
return kidStrategy;
}
public Algorithm getAlgorithm() {
return algorithm;
}
@Override
public boolean hasIdRequirement() {
return kidStrategy.equals(KidStrategy.BASE64_ENCODED_KEY_ID);
}
@Override
public boolean allowKidAbsent() {
return kidStrategy.equals(KidStrategy.CUSTOM)
|| kidStrategy.equals(KidStrategy.IGNORED);
}
@Override
public boolean equals(Object o) {
if (!(o instanceof JwtHmacParameters)) {
return false;
}
JwtHmacParameters that = (JwtHmacParameters) o;
return that.keySizeBytes == keySizeBytes
&& that.kidStrategy.equals(kidStrategy)
&& that.algorithm.equals(algorithm);
}
@Override
public int hashCode() {
return Objects.hash(JwtHmacParameters.class, keySizeBytes, kidStrategy, algorithm);
}
@Override
public String toString() {
return "JWT HMAC Parameters (kidStrategy: "
+ kidStrategy
+ ", Algorithm "
+ algorithm
+ ", and "
+ keySizeBytes
+ "-byte key)";
}
}
|
