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19  package org.apache.shiro.authc.credential;
20  
21  import org.apache.shiro.authc.AuthenticationInfo;
22  import org.apache.shiro.authc.AuthenticationToken;
23  import org.apache.shiro.authc.SaltedAuthenticationInfo;
24  import org.apache.shiro.codec.Base64;
25  import org.apache.shiro.codec.Hex;
26  import org.apache.shiro.crypto.hash.AbstractHash;
27  import org.apache.shiro.crypto.hash.Hash;
28  import org.apache.shiro.crypto.hash.SimpleHash;
29  import org.apache.shiro.util.StringUtils;
30  
31  /**
32   * A {@code HashedCredentialMatcher} provides support for hashing of supplied {@code AuthenticationToken} credentials
33   * before being compared to those in the {@code AuthenticationInfo} from the data store.
34   * <p/>
35   * Credential hashing is one of the most common security techniques when safeguarding a user's private credentials
36   * (passwords, keys, etc).  Most developers never want to store their users' credentials in plain form, viewable by
37   * anyone, so they often hash the users' credentials before they are saved in the data store.
38   * <p/>
39   * This class (and its subclasses) function as follows:
40   * <ol>
41   * <li>Hash the {@code AuthenticationToken} credentials supplied by the user during their login.</li>
42   * <li>Compare this hashed value directly with the {@code AuthenticationInfo} credentials stored in the system
43   * (the stored account credentials are expected to already be in hashed form).</li>
44   * <li>If these two values are {@link #equals(Object, Object) equal}, the submitted credentials match, otherwise
45   * they do not.</li>
46   * </ol>
47   * <h2>Salting and Multiple Hash Iterations</h2>
48   * Because simple hashing is usually not good enough for secure applications, this class also supports 'salting'
49   * and multiple hash iterations.  Please read this excellent
50   * <a href="http://www.owasp.org/index.php/Hashing_Java" _target="blank">Hashing Java article</a> to learn about
51   * salting and multiple iterations and why you might want to use them. (Note of sections 5
52   * &quot;Why add salt?&quot; and 6 "Hardening against the attacker's attack").   We should also note here that all of
53   * Shiro's Hash implementations (for example, {@link org.apache.shiro.crypto.hash.Md5Hash Md5Hash},
54   * {@link org.apache.shiro.crypto.hash.Sha1Hash Sha1Hash}, etc) support salting and multiple hash iterations via
55   * overloaded constructors.
56   * <h4>Real World Case Study</h4>
57   * In April 2010, some public Atlassian Jira and Confluence
58   * installations (Apache Software Foundation, Codehaus, etc) were the target of account attacks and user accounts
59   * were compromised.  The reason?  Jira and Confluence at the time did not salt user passwords and attackers were
60   * able to use dictionary attacks to compromise user accounts (Atlassian has since
61   * <a href="http://blogs.atlassian.com/news/2010/04/oh_man_what_a_day_an_update_on_our_security_breach.html">
62   * fixed the problem</a> of course).
63   * <p/>
64   * The lesson?
65   * <p/>
66   * <b>ALWAYS, ALWAYS, ALWAYS SALT USER PASSWORDS!</b>
67   * <p/>
68   * <h3>Salting</h3>
69   * Prior to Shiro 1.1, salts could be obtained based on the end-user submitted
70   * {@link AuthenticationToken AuthenticationToken} via the now-deprecated
71   * {@link #getSalt(org.apache.shiro.authc.AuthenticationToken) getSalt(AuthenticationToken)} method.  This however
72   * could constitute a security hole since ideally salts should never be obtained based on what a user can submit.
73   * User-submitted salt mechanisms are <em>much</em> more susceptible to dictionary attacks and <b>SHOULD NOT</b> be
74   * used in secure systems.  Instead salts should ideally be a secure randomly-generated number that is generated when
75   * the user account is created.  The secure number should never be disseminated to the user and always kept private
76   * by the application.
77   * <h4>Shiro 1.1</h4>
78   * As of Shiro 1.1, it is expected that any salt used to hash the submitted credentials will be obtained from the
79   * stored account information (represented as an {@link AuthenticationInfo AuthenticationInfo} instance).  This is much
80   * more secure because the salt value remains private to the application (Shiro will never store this value).
81   * <p/>
82   * To enable this, {@code Realm}s should return {@link SaltedAuthenticationInfo SaltedAuthenticationInfo} instances
83   * during authentication.  {@code HashedCredentialsMatcher} implementations will then use the provided
84   * {@link org.apache.shiro.authc.SaltedAuthenticationInfo#getCredentialsSalt credentialsSalt} for hashing.  To avoid
85   * security risks,
86   * <b>it is highly recommended that any existing {@code Realm} implementations that support hashed credentials are
87   * updated to return {@link SaltedAuthenticationInfo SaltedAuthenticationInfo} instances as soon as possible</b>.
88   * <h4>Shiro 1.0 Backwards Compatibility</h4>
89   * Because of the identified security risk, {@code Realm} implementations that support credentials hashing should
90   * be updated to return {@link SaltedAuthenticationInfo SaltedAuthenticationInfo} instances as
91   * soon as possible.
92   * <p/>
93   * If this is not possible for some reason, this class will retain 1.0 backwards-compatible behavior of obtaining
94   * the salt via the now-deprecated {@link #getSalt(AuthenticationToken) getSalt(AuthenticationToken)} method.  This
95   * method will only be invoked if a {@code Realm} <em>does not</em> return
96   * {@link SaltedAuthenticationInfo SaltedAutenticationInfo} instances and {@link #isHashSalted() hashSalted} is
97   * {@code true}.
98   * But please note that the {@link #isHashSalted() hashSalted} property and the
99   * {@link #getSalt(AuthenticationToken) getSalt(AuthenticationToken)} methods will be removed before the Shiro 2.0
100  * release.
101  * <h3>Multiple Hash Iterations</h3>
102  * If you hash your users' credentials multiple times before persisting to the data store, you will also need to
103  * set this class's {@link #setHashIterations(int) hashIterations} property.  See the
104  * <a href="http://www.owasp.org/index.php/Hashing_Java" _target="blank">Hashing Java article</a>'s
105  * <a href="http://www.owasp.org/index.php/Hashing_Java#Hardening_against_the_attacker.27s_attack">
106  * &quot;Hardening against the attacker's attack&quot;</a> section to learn more about why you might want to use
107  * multiple hash iterations.
108  * <h2>MD5 &amp; SHA-1 Notice</h2>
109  * <a href="http://en.wikipedia.org/wiki/MD5">MD5</a> and
110  * <a href="http://en.wikipedia.org/wiki/SHA_hash_functions">SHA-1</a> algorithms are now known to be vulnerable to
111  * compromise and/or collisions (read the linked pages for more).  While most applications are ok with either of these
112  * two, if your application mandates high security, use the SHA-256 (or higher) hashing algorithms and their
113  * supporting {@code CredentialsMatcher} implementations.
114  *
115  * @see org.apache.shiro.crypto.hash.Md5Hash
116  * @see org.apache.shiro.crypto.hash.Sha1Hash
117  * @see org.apache.shiro.crypto.hash.Sha256Hash
118  * @since 0.9
119  */
120 public class HashedCredentialsMatcher extends SimpleCredentialsMatcher {
121 
122     /**
123      * @since 1.1
124      */
125     private String hashAlgorithm;
126     private int hashIterations;
127     private boolean hashSalted;
128     private boolean storedCredentialsHexEncoded;
129 
130     /**
131      * JavaBeans-compatibile no-arg constructor intended for use in IoC/Dependency Injection environments.  If you
132      * use this constructor, you <em>MUST</em> also additionally set the
133      * {@link #setHashAlgorithmName(String) hashAlgorithmName} property.
134      */
135     public HashedCredentialsMatcher() {
136         this.hashAlgorithm = null;
137         this.hashSalted = false;
138         this.hashIterations = 1;
139         this.storedCredentialsHexEncoded = true; //false means Base64-encoded
140     }
141 
142     /**
143      * Creates an instance using the specified {@link #getHashAlgorithmName() hashAlgorithmName} to hash submitted
144      * credentials.
145      * @param hashAlgorithmName the {@code Hash} {@link org.apache.shiro.crypto.hash.Hash#getAlgorithmName() algorithmName}
146      *                          to use when performing hashes for credentials matching.
147      * @since 1.1
148      */
149     public HashedCredentialsMatcher(String hashAlgorithmName) {
150         this();
151         if (!StringUtils.hasText(hashAlgorithmName) ) {
152             throw new IllegalArgumentException("hashAlgorithmName cannot be null or empty.");
153         }
154         this.hashAlgorithm = hashAlgorithmName;
155     }
156 
157     /**
158      * Returns the {@code Hash} {@link org.apache.shiro.crypto.hash.Hash#getAlgorithmName() algorithmName} to use
159      * when performing hashes for credentials matching.
160      *
161      * @return the {@code Hash} {@link org.apache.shiro.crypto.hash.Hash#getAlgorithmName() algorithmName} to use
162      *         when performing hashes for credentials matching.
163      * @since 1.1
164      */
165     public String getHashAlgorithmName() {
166         return hashAlgorithm;
167     }
168 
169     /**
170      * Sets the {@code Hash} {@link org.apache.shiro.crypto.hash.Hash#getAlgorithmName() algorithmName} to use
171      * when performing hashes for credentials matching.
172      *
173      * @param hashAlgorithmName the {@code Hash} {@link org.apache.shiro.crypto.hash.Hash#getAlgorithmName() algorithmName}
174      *                          to use when performing hashes for credentials matching.
175      * @since 1.1
176      */
177     public void setHashAlgorithmName(String hashAlgorithmName) {
178         this.hashAlgorithm = hashAlgorithmName;
179     }
180 
181     /**
182      * Returns {@code true} if the system's stored credential hash is Hex encoded, {@code false} if it
183      * is Base64 encoded.
184      * <p/>
185      * Default value is {@code true} for convenience - all of Shiro's {@link Hash Hash#toString()}
186      * implementations return Hex encoded values by default, making this class's use with those implementations
187      * easier.
188      *
189      * @return {@code true} if the system's stored credential hash is Hex encoded, {@code false} if it
190      *         is Base64 encoded.  Default is {@code true}
191      */
192     public boolean isStoredCredentialsHexEncoded() {
193         return storedCredentialsHexEncoded;
194     }
195 
196     /**
197      * Sets the indicator if this system's stored credential hash is Hex encoded or not.
198      * <p/>
199      * A value of {@code true} will cause this class to decode the system credential from Hex, a
200      * value of {@code false} will cause this class to decode the system credential from Base64.
201      * <p/>
202      * Unless overridden via this method, the default value is {@code true} for convenience - all of Shiro's
203      * {@link Hash Hash#toString()} implementations return Hex encoded values by default, making this class's use with
204      * those implementations easier.
205      *
206      * @param storedCredentialsHexEncoded the indicator if this system's stored credential hash is Hex
207      *                                    encoded or not ('not' automatically implying it is Base64 encoded).
208      */
209     public void setStoredCredentialsHexEncoded(boolean storedCredentialsHexEncoded) {
210         this.storedCredentialsHexEncoded = storedCredentialsHexEncoded;
211     }
212 
213     /**
214      * Returns {@code true} if a submitted {@code AuthenticationToken}'s credentials should be salted when hashing,
215      * {@code false} if it should not be salted.
216      * <p/>
217      * If enabled, the salt used will be obtained via the {@link #getSalt(AuthenticationToken) getSalt} method.
218      * <p/>
219      * The default value is {@code false}.
220      *
221      * @return {@code true} if a submitted {@code AuthenticationToken}'s credentials should be salted when hashing,
222      *         {@code false} if it should not be salted.
223      * @deprecated since Shiro 1.1.  Hash salting is now expected to be based on if the {@link AuthenticationInfo}
224      *             returned from the {@code Realm} is a {@link SaltedAuthenticationInfo} instance and its
225      *             {@link org.apache.shiro.authc.SaltedAuthenticationInfo#getCredentialsSalt() getCredentialsSalt()} method returns a non-null value.
226      *             This method and the 1.0 behavior still exists for backwards compatibility if the {@code Realm} does not return
227      *             {@code SaltedAuthenticationInfo} instances, but <b>it is highly recommended that {@code Realm} implementations
228      *             that support hashed credentials start returning {@link SaltedAuthenticationInfo SaltedAuthenticationInfo}
229      *             instances as soon as possible</b>.
230      *             <p/>
231      *             This is because salts should always be obtained from the stored account information and
232      *             never be interpreted based on user/Subject-entered data.  User-entered data is easier to compromise for
233      *             attackers, whereas account-unique (and secure randomly-generated) salts never disseminated to the end-user
234      *             are almost impossible to break.  This method will be removed in Shiro 2.0.
235      */
236     @Deprecated
237     public boolean isHashSalted() {
238         return hashSalted;
239     }
240 
241     /**
242      * Sets whether or not to salt a submitted {@code AuthenticationToken}'s credentials when hashing.
243      * <p/>
244      * If enabled, the salt used will be obtained via the {@link #getSalt(org.apache.shiro.authc.AuthenticationToken) getCredentialsSalt} method.
245      * </p>
246      * The default value is {@code false}.
247      *
248      * @param hashSalted whether or not to salt a submitted {@code AuthenticationToken}'s credentials when hashing.
249      * @deprecated since Shiro 1.1.  Hash salting is now expected to be based on if the {@link AuthenticationInfo}
250      *             returned from the {@code Realm} is a {@link SaltedAuthenticationInfo} instance and its
251      *             {@link org.apache.shiro.authc.SaltedAuthenticationInfo#getCredentialsSalt() getCredentialsSalt()} method returns a non-null value.
252      *             This method and the 1.0 behavior still exists for backwards compatibility if the {@code Realm} does not return
253      *             {@code SaltedAuthenticationInfo} instances, but <b>it is highly recommended that {@code Realm} implementations
254      *             that support hashed credentials start returning {@link SaltedAuthenticationInfo SaltedAuthenticationInfo}
255      *             instances as soon as possible</b>.
256      *             <p/>
257      *             This is because salts should always be obtained from the stored account information and
258      *             never be interpreted based on user/Subject-entered data.  User-entered data is easier to compromise for
259      *             attackers, whereas account-unique (and secure randomly-generated) salts never disseminated to the end-user
260      *             are almost impossible to break.  This method will be removed in Shiro 2.0.
261      */
262     @Deprecated
263     public void setHashSalted(boolean hashSalted) {
264         this.hashSalted = hashSalted;
265     }
266 
267     /**
268      * Returns the number of times a submitted {@code AuthenticationToken}'s credentials will be hashed before
269      * comparing to the credentials stored in the system.
270      * <p/>
271      * Unless overridden, the default value is {@code 1}, meaning a normal hash execution will occur.
272      *
273      * @return the number of times a submitted {@code AuthenticationToken}'s credentials will be hashed before
274      *         comparing to the credentials stored in the system.
275      */
276     public int getHashIterations() {
277         return hashIterations;
278     }
279 
280     /**
281      * Sets the number of times a submitted {@code AuthenticationToken}'s credentials will be hashed before comparing
282      * to the credentials stored in the system.
283      * <p/>
284      * Unless overridden, the default value is {@code 1}, meaning a normal single hash execution will occur.
285      * <p/>
286      * If this argument is less than 1 (i.e. 0 or negative), the default value of 1 is applied.  There must always be
287      * at least 1 hash iteration (otherwise there would be no hash).
288      *
289      * @param hashIterations the number of times to hash a submitted {@code AuthenticationToken}'s credentials.
290      */
291     public void setHashIterations(int hashIterations) {
292         if (hashIterations < 1) {
293             this.hashIterations = 1;
294         } else {
295             this.hashIterations = hashIterations;
296         }
297     }
298 
299     /**
300      * Returns a salt value used to hash the token's credentials.
301      * <p/>
302      * This default implementation merely returns {@code token.getPrincipal()}, effectively using the user's
303      * identity (username, user id, etc) as the salt, a most common technique.  If you wish to provide the
304      * authentication token's salt another way, you may override this method.
305      *
306      * @param token the AuthenticationToken submitted during the authentication attempt.
307      * @return a salt value to use to hash the authentication token's credentials.
308      * @deprecated since Shiro 1.1.  Hash salting is now expected to be based on if the {@link AuthenticationInfo}
309      *             returned from the {@code Realm} is a {@link SaltedAuthenticationInfo} instance and its
310      *             {@link org.apache.shiro.authc.SaltedAuthenticationInfo#getCredentialsSalt() getCredentialsSalt()} method returns a non-null value.
311      *             This method and the 1.0 behavior still exists for backwards compatibility if the {@code Realm} does not return
312      *             {@code SaltedAuthenticationInfo} instances, but <b>it is highly recommended that {@code Realm} implementations
313      *             that support hashed credentials start returning {@link SaltedAuthenticationInfo SaltedAuthenticationInfo}
314      *             instances as soon as possible</b>.<p/>
315      *             This is because salts should always be obtained from the stored account information and
316      *             never be interpreted based on user/Subject-entered data.  User-entered data is easier to compromise for
317      *             attackers, whereas account-unique (and secure randomly-generated) salts never disseminated to the end-user
318      *             are almost impossible to break.  This method will be removed in Shiro 2.0.
319      */
320     @Deprecated
321     protected Object getSalt(AuthenticationToken token) {
322         return token.getPrincipal();
323     }
324 
325     /**
326      * Returns a {@link Hash Hash} instance representing the already-hashed AuthenticationInfo credentials stored in the system.
327      * <p/>
328      * This method reconstructs a {@link Hash Hash} instance based on a {@code info.getCredentials} call,
329      * but it does <em>not</em> hash that value - it is expected that method call will return an already-hashed value.
330      * <p/>
331      * This implementation's reconstruction effort functions as follows:
332      * <ol>
333      * <li>Convert {@code account.getCredentials()} to a byte array via the {@link #toBytes toBytes} method.
334      * <li>If {@code account.getCredentials()} was originally a String or char[] before {@code toBytes} was
335      * called, check for encoding:
336      * <li>If {@link #storedCredentialsHexEncoded storedCredentialsHexEncoded}, Hex decode that byte array, otherwise
337      * Base64 decode the byte array</li>
338      * <li>Set the byte[] array directly on the {@code Hash} implementation and return it.</li>
339      * </ol>
340      *
341      * @param info the AuthenticationInfo from which to retrieve the credentials which assumed to be in already-hashed form.
342      * @return a {@link Hash Hash} instance representing the given AuthenticationInfo's stored credentials.
343      */
344     protected Object getCredentials(AuthenticationInfo info) {
345         Object credentials = info.getCredentials();
346 
347         byte[] storedBytes = toBytes(credentials);
348 
349         if (credentials instanceof String || credentials instanceof char[]) {
350             //account.credentials were a char[] or String, so
351             //we need to do text decoding first:
352             if (isStoredCredentialsHexEncoded()) {
353                 storedBytes = Hex.decode(storedBytes);
354             } else {
355                 storedBytes = Base64.decode(storedBytes);
356             }
357         }
358         AbstractHash hash = newHashInstance();
359         hash.setBytes(storedBytes);
360         return hash;
361     }
362 
363     /**
364      * This implementation first hashes the {@code token}'s credentials, potentially using a
365      * {@code salt} if the {@code info} argument is a
366      * {@link org.apache.shiro.authc.SaltedAuthenticationInfo SaltedAuthenticationInfo}.  It then compares the hash
367      * against the {@code AuthenticationInfo}'s
368      * {@link #getCredentials(org.apache.shiro.authc.AuthenticationInfo) already-hashed credentials}.  This method
369      * returns {@code true} if those two values are {@link #equals(Object, Object) equal}, {@code false} otherwise.
370      *
371      * @param token the {@code AuthenticationToken} submitted during the authentication attempt.
372      * @param info  the {@code AuthenticationInfo} stored in the system matching the token principal
373      * @return {@code true} if the provided token credentials hash match to the stored account credentials hash,
374      *         {@code false} otherwise
375      * @since 1.1
376      */
377     @Override
378     public boolean doCredentialsMatch(AuthenticationToken token, AuthenticationInfo info) {
379         Object tokenHashedCredentials = hashProvidedCredentials(token, info);
380         Object accountCredentials = getCredentials(info);
381         return equals(tokenHashedCredentials, accountCredentials);
382     }
383 
384     /**
385      * Hash the provided {@code token}'s credentials using the salt stored with the account if the
386      * {@code info} instance is an {@code instanceof} {@link SaltedAuthenticationInfo SaltedAuthenticationInfo} (see
387      * the class-level JavaDoc for why this is the preferred approach).
388      * <p/>
389      * If the {@code info} instance is <em>not</em>
390      * an {@code instanceof} {@code SaltedAuthenticationInfo}, the logic will fall back to Shiro 1.0
391      * backwards-compatible logic:  it will first check to see {@link #isHashSalted() isHashSalted} and if so, will try
392      * to acquire the salt from {@link #getSalt(AuthenticationToken) getSalt(AuthenticationToken)}.  See the class-level
393      * JavaDoc for why this is not recommended.  This 'fallback' logic exists only for backwards-compatibility.
394      * {@code Realm}s should be updated as soon as possible to return {@code SaltedAuthenticationInfo} instances
395      * if account credentials salting is enabled (highly recommended for password-based systems).
396      *
397      * @param token the submitted authentication token from which its credentials will be hashed
398      * @param info  the stored account data, potentially used to acquire a salt
399      * @return the token credentials hash
400      * @since 1.1
401      */
402     protected Object hashProvidedCredentials(AuthenticationToken token, AuthenticationInfo info) {
403         Object salt = null;
404         if (info instanceof SaltedAuthenticationInfo) {
405             salt = ((SaltedAuthenticationInfo) info).getCredentialsSalt();
406         } else {
407             //retain 1.0 backwards compatibility:
408             if (isHashSalted()) {
409                 salt = getSalt(token);
410             }
411         }
412         return hashProvidedCredentials(token.getCredentials(), salt, getHashIterations());
413     }
414 
415     /**
416      * Returns the {@link #getHashAlgorithmName() hashAlgorithmName} property, but will throw an
417      * {@link IllegalStateException} if it has not been set.
418      *
419      * @return the required {@link #getHashAlgorithmName() hashAlgorithmName} property
420      * @throws IllegalStateException if the property has not been set prior to calling this method.
421      * @since 1.1
422      */
423     private String assertHashAlgorithmName() throws IllegalStateException {
424         String hashAlgorithmName = getHashAlgorithmName();
425         if (hashAlgorithmName == null) {
426             String msg = "Required 'hashAlgorithmName' property has not been set.  This is required to execute " +
427                     "the hashing algorithm.";
428             throw new IllegalStateException(msg);
429         }
430         return hashAlgorithmName;
431     }
432 
433     /**
434      * Hashes the provided credentials a total of {@code hashIterations} times, using the given salt.  The hash
435      * implementation/algorithm used is based on the {@link #getHashAlgorithmName() hashAlgorithmName} property.
436      *
437      * @param credentials    the submitted authentication token's credentials to hash
438      * @param salt           the value to salt the hash, or {@code null} if a salt will not be used.
439      * @param hashIterations the number of times to hash the credentials.  At least one hash will always occur though,
440      *                       even if this argument is 0 or negative.
441      * @return the hashed value of the provided credentials, according to the specified salt and hash iterations.
442      */
443     protected Hash hashProvidedCredentials(Object credentials, Object salt, int hashIterations) {
444         String hashAlgorithmName = assertHashAlgorithmName();
445         return new SimpleHash(hashAlgorithmName, credentials, salt, hashIterations);
446     }
447 
448     /**
449      * Returns a new, <em>uninitialized</em> instance, without its byte array set.  Used as a utility method in the
450      * {@link SimpleCredentialsMatcher#getCredentials(org.apache.shiro.authc.AuthenticationInfo) getCredentials(AuthenticationInfo)} implementation.
451      *
452      * @return a new, <em>uninitialized</em> instance, without its byte array set.
453      */
454     protected AbstractHash newHashInstance() {
455         String hashAlgorithmName = assertHashAlgorithmName();
456         return new SimpleHash(hashAlgorithmName);
457     }
458 
459 }