1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.shiro.crypto;
20
21 import org.apache.shiro.util.ByteSource;
22
23 import java.io.InputStream;
24 import java.io.OutputStream;
25
26 /**
27 * A {@code CipherService} uses a cryptographic algorithm called a
28 * <a href="http://en.wikipedia.org/wiki/Cipher">Cipher</a> to convert an original input source using a {@code key} to
29 * an uninterpretable format. The resulting encrypted output is only able to be converted back to original form with
30 * a {@code key} as well. {@code CipherService}s can perform both encryption and decryption.
31 * <h2>Cipher Basics</h2>
32 * For what is known as <em>Symmetric</em> {@code Cipher}s, the {@code Key} used to encrypt the source is the same
33 * as (or trivially similar to) the {@code Key} used to decrypt it.
34 * <p/>
35 * For <em>Asymmetric</em> {@code Cipher}s, the encryption {@code Key} is not the same as the decryption {@code Key}.
36 * The most common type of Asymmetric Ciphers are based on what is called public/private key pairs:
37 * <p/>
38 * A <em>private</em> key is known only to a single party, and as its name implies, is supposed be kept very private
39 * and secure. A <em>public</em> key that is associated with the private key can be disseminated freely to anyone.
40 * Then data encrypted by the public key can only be decrypted by the private key and vice versa, but neither party
41 * need share their private key with anyone else. By not sharing a private key, you can guarantee no 3rd party can
42 * intercept the key and therefore use it to decrypt a message.
43 * <p/>
44 * This asymmetric key technology was created as a
45 * more secure alternative to symmetric ciphers that sometimes suffer from man-in-the-middle attacks since, for
46 * data shared between two parties, the same Key must also be shared and may be compromised.
47 * <p/>
48 * Note that a symmetric cipher is perfectly fine to use if you just want to encode data in a format no one else
49 * can understand and you never give away the key. Shiro uses a symmetric cipher when creating certain
50 * HTTP Cookies for example - because it is often undesirable to have user's identity stored in a plain-text cookie,
51 * that identity can be converted via a symmetric cipher. Since the the same exact Shiro application will receive
52 * the cookie, it can decrypt it via the same {@code Key} and there is no potential for discovery since that Key
53 * is never shared with anyone.
54 * <h2>{@code CipherService}s vs JDK {@link javax.crypto.Cipher Cipher}s</h2>
55 * Shiro {@code CipherService}s essentially do the same things as JDK {@link javax.crypto.Cipher Cipher}s, but in
56 * simpler and easier-to-use ways for most application developers. When thinking about encrypting and decrypting data
57 * in an application, most app developers want what a {@code CipherService} provides, rather than having to manage the
58 * lower-level intricacies of the JDK's {@code Cipher} API. Here are a few reasons why most people prefer
59 * {@code CipherService}s:
60 * <ul>
61 * <li><b>Stateless Methods</b> - {@code CipherService} method calls do not retain state between method invocations.
62 * JDK {@code Cipher} instances do retain state across invocations, requiring its end-users to manage the instance
63 * and its state themselves.</li>
64 * <li><b>Thread Safety</b> - {@code CipherService} instances are thread-safe inherently because no state is
65 * retained across method invocations. JDK {@code Cipher} instances retain state and cannot be used by multiple
66 * threads concurrently.</li>
67 * <li><b>Single Operation</b> - {@code CipherService} method calls are single operation methods: encryption or
68 * decryption in their entirety are done as a single method call. This is ideal for the large majority of developer
69 * needs where you have something unencrypted and just want it decrypted (or vice versa) in a single method call. In
70 * contrast, JDK {@code Cipher} instances can support encrypting/decrypting data in chunks over time (because it
71 * retains state), but this often introduces API clutter and confusion for most application developers.</li>
72 * <li><b>Type Safe</b> - There are {@code CipherService} implementations for different Cipher algorithms
73 * ({@code AesCipherService}, {@code BlowfishCipherService}, etc). There is only one JDK {@code Cipher} class to
74 * represent all cipher algorithms/instances.
75 * <li><b>Simple Construction</b> - Because {@code CipherService} instances are type-safe, instantiating and using
76 * one is often as simple as calling the default constructor, for example, <code>new AesCipherService();</code>. The
77 * JDK {@code Cipher} class however requires using a procedural factory method with String arguments to indicate how
78 * the instance should be created. The String arguments themselves are somewhat cryptic and hard to
79 * understand unless you're a security expert. Shiro hides these details from you, but allows you to configure them
80 * if you want.</li>
81 * </ul>
82 *
83 * @see BlowfishCipherService
84 * @see AesCipherService
85 * @since 1.0
86 */
87 public interface CipherService {
88
89 /**
90 * Decrypts encrypted data via the specified cipher key and returns the original (pre-encrypted) data.
91 * Note that the key must be in a format understood by the CipherService implementation.
92 *
93 * @param encrypted the previously encrypted data to decrypt
94 * @param decryptionKey the cipher key used during decryption.
95 * @return a byte source representing the original form of the specified encrypted data.
96 * @throws CryptoException if there is an error during decryption
97 */
98 ByteSource decrypt(byte[] encrypted, byte[] decryptionKey) throws CryptoException;
99
100 /**
101 * Receives encrypted data from the given {@code InputStream}, decrypts it, and sends the resulting decrypted data
102 * to the given {@code OutputStream}.
103 * <p/>
104 * <b>NOTE:</b> This method <em>does NOT</em> flush or close either stream prior to returning - the caller must
105 * do so when they are finished with the streams. For example:
106 * <pre>
107 * try {
108 * InputStream in = ...
109 * OutputStream out = ...
110 * cipherService.decrypt(in, out, decryptionKey);
111 * } finally {
112 * if (in != null) {
113 * try {
114 * in.close();
115 * } catch (IOException ioe1) { ... log, trigger event, etc }
116 * }
117 * if (out != null) {
118 * try {
119 * out.close();
120 * } catch (IOException ioe2) { ... log, trigger event, etc }
121 * }
122 * }
123 * </pre>
124 *
125 * @param in the stream supplying the data to decrypt
126 * @param out the stream to send the decrypted data
127 * @param decryptionKey the cipher key to use for decryption
128 * @throws CryptoException if there is any problem during decryption.
129 */
130 void decrypt(InputStream in, OutputStream out, byte[] decryptionKey) throws CryptoException;
131
132 /**
133 * Encrypts data via the specified cipher key. Note that the key must be in a format understood by
134 * the {@code CipherService} implementation.
135 *
136 * @param raw the data to encrypt
137 * @param encryptionKey the cipher key used during encryption.
138 * @return a byte source with the encrypted representation of the specified raw data.
139 * @throws CryptoException if there is an error during encryption
140 */
141 ByteSource encrypt(byte[] raw, byte[] encryptionKey) throws CryptoException;
142
143 /**
144 * Receives the data from the given {@code InputStream}, encrypts it, and sends the resulting encrypted data to the
145 * given {@code OutputStream}.
146 * <p/>
147 * <b>NOTE:</b> This method <em>does NOT</em> flush or close either stream prior to returning - the caller must
148 * do so when they are finished with the streams. For example:
149 * <pre>
150 * try {
151 * InputStream in = ...
152 * OutputStream out = ...
153 * cipherService.encrypt(in, out, encryptionKey);
154 * } finally {
155 * if (in != null) {
156 * try {
157 * in.close();
158 * } catch (IOException ioe1) { ... log, trigger event, etc }
159 * }
160 * if (out != null) {
161 * try {
162 * out.close();
163 * } catch (IOException ioe2) { ... log, trigger event, etc }
164 * }
165 * }
166 * </pre>
167 *
168 * @param in the stream supplying the data to encrypt
169 * @param out the stream to send the encrypted data
170 * @param encryptionKey the cipher key to use for encryption
171 * @throws CryptoException if there is any problem during encryption.
172 */
173 void encrypt(InputStream in, OutputStream out, byte[] encryptionKey) throws CryptoException;
174
175 }