1 page.title=Signing Your Applications 2 @jd:body 3 4 <div id="qv-wrapper"> 5 <div id="qv"> 6 7 <h2>Quickview</h2> 8 9 <ul> 10 <li>All Android apps <em>must</em> be signed</a></li> 11 <li>You can sign with a self-signed key</li> 12 <li>How you sign your apps is critical — read this document carefully</li> 13 <li>Determine your signing strategy early in the development process</li> 14 </ul> 15 16 <h2>In this document</h2> 17 18 <ol> 19 <li><a href="#overview">Overview</a></li> 20 <li><a href="#strategies">Signing Strategies</a></li> 21 <li><a href="#setup">Basic Setup for Signing</a></li> 22 <li><a href="#debugmode">Signing in Debug Mode</a></li> 23 <li><a href="#releasemode">Signing for Public Release</a> 24 <ol> 25 <li><a href="#cert">Obtain a suitable private key</a></li> 26 <li><a href="#releasecompile">Compile the application in release mode</a></li> 27 <li><a href="#signapp">Sign your application with your private key</a></li> 28 <li><a href="#align">Align the final APK package</a></li> 29 <li><a href="#ExportWizard">Compile and sign with Eclipse ADT</a></li> 30 </ol> 31 </li> 32 <li><a href="#secure-key">Securing Your Private Key</a></li> 33 34 </ol> 35 36 <h2>See also</h2> 37 38 <ol> 39 <li><a href="{@docRoot}guide/publishing/versioning.html">Versioning Your Applications</a></li> 40 <li><a href="{@docRoot}guide/publishing/preparing.html">Preparing to Publish</a></li> 41 </ol> 42 43 </div> 44 </div> 45 46 <p>This document provides information about signing your Android applications prior to publishing them for mobile device users.</p> 47 48 <h2 id="overview">Overview</h2> 49 50 <p>The Android system requires that all installed applications be digitally 51 signed with a certificate whose private key is held by the application's 52 developer. The Android system uses the certificate as a means of identifying the author of 53 an application and establishing trust relationships between applications. The certificate is not 54 used to control which applications the user can install. The certificate 55 does not need to be signed by a certificate authority: it is perfectly 56 allowable, and typical, for Android applications to use self-signed 57 certificates.</p> 58 59 <p>The important points to understand about signing Android applications are:</p> 60 61 <ul> 62 <li>All applications <em>must</em> be signed. The system will not install an application 63 that is not signed.</li> 64 <li>You can use self-signed certificates to sign your applications. No certificate authority 65 is needed.</li> 66 <li>When you are ready to release your application for end-users, you must sign it with a suitable private 67 key. You can not publish an application that is signed with the debug key generated 68 by the SDK tools. 69 </li> 70 <li>The system tests a signer certificate's expiration date only at install time. If an 71 application's signer certificate expires after the application is installed, the application 72 will continue to function normally.</li> 73 <li>You can use standard tools — Keytool and Jarsigner — to generate keys and 74 sign your application .apk files.</li> 75 <li>Once you have signed the application, use the <code>zipalign</code> tool to optimize the final APK package.</li> 76 </ul> 77 78 <p>The Android system will not install or run an application that is not signed appropriately. This 79 applies wherever the Android system is run, whether on an actual device or on the emulator. 80 For this reason, you must set up signing for your application before you will be able to 81 run or debug it on an emulator or device.</p> 82 83 <p>The Android SDK tools assist you in signing your applications when debugging. Both the ADT Plugin 84 for Eclipse and the Ant build tool offer two signing modes — <em>debug mode</em> 85 and <em>release mode</em>. 86 87 <ul> 88 <li>While developing and testing, you can compile in debug mode. 89 In debug mode, the build tools use the Keytool utility, included in the JDK, to create 90 a keystore and key with a known alias and password. At each compilation, the tools then use 91 the debug key to sign the application .apk file. Because the password is known, the tools 92 don't need to prompt you for the keystore/key password each time you compile.</li> 93 94 <li>When your application is ready for release, you must compile in release mode 95 and then sign the .apk <span style="color:red">with your private key</span>. 96 There are two ways to do this: 97 <ul> 98 <li>Using Keytool and Jarsigner in the command-line. In this approach, 99 you first compile your application to an <em>unsigned</em> .apk. You must then sign 100 the .apk manually with your private key 101 using Jarsigner (or similar tool). If you do not have a suitable private key already, 102 you can run Keytool manually to generate your own keystore/key and then sign your 103 application with Jarsigner.</li> 104 <li>Using the ADT Export Wizard. If you are developing in Eclipse with the ADT plugin, 105 you can use the Export Wizard to compile the application, generate a private key 106 (if necessary), and sign the .apk, all in a single process using the Export Wizard. 107 </li> 108 </ul> 109 </li> 110 </ul> 111 112 <p>Once your application is signed, don't forget to run {@code zipalign} on the APK 113 for additional optimization.</p> 114 115 <h2 id="strategies">Signing Strategies</h2> 116 117 <p>Some aspects of application signing may affect how you approach the development 118 of your application, especially if you are planning to release multiple 119 applications. </p> 120 121 <p>In general, the recommended strategy for all developers is to sign 122 all of your applications with the same certificate, throughout the expected 123 lifespan of your applications. There are several reasons why you should do so: </p> 124 125 <ul> 126 <li>Application upgrade – As you release updates to your application, you 127 will want to continue to sign the updates with the same certificate or set of 128 certificates, if you want users to upgrade seamlessly to the new version. When 129 the system is installing an update to an application, it compares the 130 certificate(s) in the new version with those in the existing version. If the 131 certificates match exactly, including both the certificate data and order, then 132 the system allows the update. If you sign the new version without using matching 133 certificates, you will also need to assign a different package name to the 134 application — in this case, the user installs the new version as a 135 completely new application. </li> 136 137 <li>Application modularity – The Android system allows applications that 138 are signed by the same certificate to run in the same process, if the 139 applications so requests, so that the system treats them as a single application. 140 In this way you can deploy your application in modules, and users can update 141 each of the modules independently if needed.</li> 142 143 <li>Code/data sharing through permissions – The Android system provides 144 signature-based permissions enforcement, so that an application can expose 145 functionality to another application that is signed with a specified 146 certificate. By signing multiple applications with the same certificate and 147 using signature-based permissions checks, your applications can share code and 148 data in a secure manner. </li> 149 150 </ul> 151 152 <p>Another important consideration in determining your signing strategy is 153 how to set the validity period of the key that you will use to sign your 154 applications.</p> 155 156 <ul> 157 <li>If you plan to support upgrades for a single application, you should ensure 158 that your key has a validity period that exceeds the expected lifespan of 159 that application. A validity period of 25 years or more is recommended. 160 When your key's validity period expires, users will no longer be 161 able to seamlessly upgrade to new versions of your application.</li> 162 163 <li>If you will sign multiple distinct applications with the same key, 164 you should ensure that your key's validity period exceeds the expected 165 lifespan of <em>all versions of all of the applications</em>, including 166 dependent applications that may be added to the suite in the future. </li> 167 168 <li>If you plan to publish your application(s) on Android Market, the 169 key you use to sign the application(s) must have a validity period 170 ending after 22 October 2033. The Market server enforces this requirement 171 to ensure that users can seamlessly upgrade Market applications when 172 new versions are available. </li> 173 </ul> 174 175 <p>As you design your application, keep these points in mind and make sure to 176 use a <a href="#cert">suitable certificate</a> to sign your applications. </p> 177 178 <h2 id="setup">Basic Setup for Signing</h2> 179 180 <p>Before you begin, you should make sure that 181 Keytool is available to the SDK build 182 tools. In most cases, you can tell the SDK build tools how to find Keytool by setting 183 your <code>JAVA_HOME</code> environment variable to references a suitable JDK. 184 Alternatively, you can add the JDK version of Keytool to your <code>PATH</code> variable.</p> 185 186 <p>If you are developing on a version of Linux that originally came with GNU Compiler for 187 Java, make sure that the system is using the JDK version of Keytool, rather than the gcj 188 version. If Keytool is already in your <code>PATH</code>, it might be pointing to a symlink at 189 <code>/usr/bin/keytool</code>. In this case, check the symlink target to be sure it points 190 to the Keytool in the JDK.</p> 191 192 <p>If you will release your application to the public, you will also need to have 193 the Jarsigner tool available on your machine. Both Jarsigner and Keytool are included 194 in the JDK. </p> 195 196 <h2 id="debugmode">Signing in Debug Mode</h2> 197 198 <p>The Android build tools provide a debug signing mode that makes it easier for you 199 to develop and debug your application, while still meeting the Android system 200 requirement for signing your .apk. 201 When using debug mode to build your app, the SDK tools invoke Keytool to automatically create 202 a debug keystore and key. This debug key is then used to automatically sign the .apk, so 203 you do not need to sign the package with your own key.</p> 204 205 <p>The SDK tools create the debug keystore/key with predetermined names/passwords:</p> 206 <ul> 207 <li>Keystore name: "debug.keystore"</li> 208 <li>Keystore password: "android"</li> 209 <li>Key alias: "androiddebugkey"</li> 210 <li>Key password: "android"</li> 211 <li>CN: "CN=Android Debug,O=Android,C=US"</li> 212 </ul></p> 213 214 <p>If necessary, you can change the location/name of the debug keystore/key or 215 supply a custom debug keystore/key to use. However, any custom debug 216 keystore/key must use the same keystore/key names and passwords as the default 217 debug key (as described above). (To do so in Eclipse/ADT, go to 218 <strong>Windows</strong> > <strong>Preferences</strong> > 219 <strong>Android</strong> > <strong>Build</strong>.) </p> 220 221 <p class="caution"><strong>Caution:</strong> You <em>cannot</em> release your application 222 to the public when signed with the debug certificate.</p> 223 224 <h3>Eclipse Users</h3> 225 226 <p>If you are developing in Eclipse/ADT (and have set up Keytool as described above in 227 <a href="#setup">Basic Setup for Signing</a>), 228 signing in debug mode is enabled by default. When you run or debug your 229 application, ADT signs the .apk with the debug certificate, runs {@code zipalign} on the 230 package, then installs it on 231 the selected emulator or connected device. No specific action on your part is needed, 232 provided ADT has access to Keytool.</p> 233 234 <h3>Ant Users</h3> 235 236 <p>If you are using Ant to build your .apk files, debug signing mode 237 is enabled by using the <code>debug</code> option with the <code>ant</code> command 238 (assuming that you are using a <code>build.xml</code> file generated by the 239 <code>android</code> tool). When you run <code>ant debug</code> to 240 compile your app, the build script generates a keystore/key and signs the .apk for you. 241 The script then also aligns the .apk with the <code>zipalign</code> tool. 242 No other action on your part is needed. Read 243 <a href="{@docRoot}guide/developing/other-ide.html#DebugMode">Developing In Other IDEs: Building 244 in debug mode</a> for more information.</p> 245 246 247 <h3 id="debugexpiry">Expiry of the Debug Certificate</h3> 248 249 <p>The self-signed certificate used to sign your application in debug mode (the default on 250 Eclipse/ADT and Ant builds) will have an expiration date of 365 days from its creation date.</p> 251 252 <p>When the certificate expires, you will get a build error. On Ant builds, the error 253 looks like this:</p> 254 255 <pre>debug: 256 [echo] Packaging bin/samples-debug.apk, and signing it with a debug key... 257 [exec] Debug Certificate expired on 8/4/08 3:43 PM</pre> 258 259 <p>In Eclipse/ADT, you will see a similar error in the Android console.</p> 260 261 <p>To fix this problem, simply delete the <code>debug.keystore</code> file. 262 The default storage location for AVDs is in <code>~/.android/avd</code> on OS X and Linux, 263 in <code>C:\Documents and Settings\<user>\.android\</code> on Windows XP, and in 264 <code>C:\Users\<user>\.android\</code> on Windows Vista.</p> 265 266 267 <p>The next time you build, the build tools will regenerate a new keystore and debug key.</p> 268 269 <p>Note that, if your development machine is using a non-Gregorian locale, the build 270 tools may erroneously generate an already-expired debug certificate, so that you get an 271 error when trying to compile your application. For workaround information, see the 272 troubleshooting topic <a href="{@docRoot}resources/faq/troubleshooting.html#signingcalendar"> 273 I can't compile my app because the build tools generated an expired debug 274 certificate</a>. </p> 275 276 277 <h2 id="releasemode">Signing for Public Release</h2> 278 279 <p>When your application is ready for release to other users, you must:</p> 280 <ol> 281 <li><a href="#cert">Obtain a suitable private key</a></li> 282 <li><a href="#releasecompile">Compile the application in release mode</li> 283 <li><a href="#signapp">Sign your application with your private key</a></li> 284 <li><a href="#align">Align the final APK package</a></li> 285 </ol> 286 287 <p>If you are developing in Eclipse with the ADT plugin, you can use the Export Wizard 288 to perform the compile, sign, and align procedures. The Export Wizard even allows you to 289 generate a new keystore and private key in the process. So if you use Eclipse, you can 290 skip to <a href="#ExportWizard">Compile and sign with Eclipse ADT</a>.</p> 291 292 293 294 <h3 id="cert">1. Obtain a suitable private key</h3> 295 296 <p>In preparation for signing your application, you must first ensure that 297 you have a suitable private key with which to sign. A suitable private 298 key is one that:</p> 299 300 <ul> 301 <li>Is in your possession</li> 302 <li>Represents the personal, corporate, or organizational entity to be identified 303 with the application</li> 304 <li>Has a validity period that exceeds the expected lifespan of the application 305 or application suite. A validity period of more than 25 years is recommended. 306 <p>If you plan to publish your application(s) on Android Market, note that a 307 validity period ending after 22 October 2033 is a requirement. You can not upload an 308 application if it is signed with a key whose validity expires before that date. 309 </p></li> 310 <li>Is not the debug key generated by the Android SDK tools. </li> 311 </ul> 312 313 <p>The key may be self-signed. If you do not have a suitable key, you must 314 generate one using Keytool. Make sure that you have Keytool available, as described 315 in <a href="#setup">Basic Setup</a>.</p> 316 317 <p>To generate a self-signed key with Keytool, use the <code>keytool</code> 318 command and pass any of the options listed below (and any others, as 319 needed). </p> 320 321 <p class="warning"><strong>Warning:</strong> Keep your private key secure. 322 Before you run Keytool, make sure to read 323 <a href="#secure-key">Securing Your Private Key</a> for a discussion of how to keep 324 your key secure and why doing so is critically important to you and to users. In 325 particular, when you are generating your key, you should select strong passwords 326 for both the keystore and key.</p> 327 328 <table> 329 <tr> 330 <th>Keytool Option</th> 331 <th>Description</th> 332 </tr> 333 <tr> 334 <td><code>-genkey</code></td><td>Generate a key pair (public and private 335 keys)</td> 336 </tr> 337 <tr> 338 <td><code>-v</code></td><td>Enable verbose output.</td> 339 </tr> 340 <tr> 341 <td><code>-alias <alias_name></code></td><td>An alias for the key. Only 342 the first 8 characters of the alias are used.</td> 343 </tr> 344 <tr> 345 <td><code>-keyalg <alg></code></td><td>The encryption algorithm to use 346 when generating the key. Both DSA and RSA are supported.</td> 347 </tr> 348 <tr> 349 <td><code>-keysize <size></code></td><td>The size of each generated key 350 (bits). If not supplied, Keytool uses a default key size of 1024 bits. In 351 general, we recommend using a key size of 2048 bits or higher. </td> 352 </tr> 353 <tr> 354 <td><code>-dname <name></code></td><td><p>A Distinguished Name that describes 355 who created the key. The value is used as the issuer and subject fields in the 356 self-signed certificate. </p><p>Note that you do not need to specify this option 357 in the command line. If not supplied, Jarsigner prompts you to enter each 358 of the Distinguished Name fields (CN, OU, and so on).</p></td> 359 </tr> 360 <tr> 361 <td><code>-keypass <password></code></td><td><p>The password for the 362 key.</p> <p>As a security precaution, do not include this option in your command 363 line. If not supplied, Keytool prompts you to enter the password. In this way, 364 your password is not stored in your shell history.</p></td> 365 </tr> 366 <tr> 367 <td><code>-validity <valdays></code></td><td><p>The validity period for the 368 key, in days. </p><p><strong>Note:</strong> A value of 10000 or greater is recommended.</p></td> 369 </tr> 370 <tr> 371 <td><code>-keystore <keystore-name>.keystore</code></td><td>A name 372 for the keystore containing the private key.</td> 373 </tr> 374 <tr> 375 <td><code>-storepass <password></code></td><td><p>A password for the 376 keystore.</p><p>As a security precaution, do not include this option in your 377 command line. If not supplied, Keytool prompts you to enter the password. In 378 this way, your password is not stored in your shell history.</p></td> 379 </tr> 380 </table> 381 382 <p>Here's an example of a Keytool command that generates a private key:</p> 383 384 <pre>$ keytool -genkey -v -keystore my-release-key.keystore 385 -alias alias_name -keyalg RSA -keysize 2048 -validity 10000</pre> 386 387 <p>Running the example command above, Keytool prompts you to provide 388 passwords for the keystore and key, and to provide the Distinguished 389 Name fields for your key. It then generates the keystore as a file called 390 <code>my-release-key.keystore</code>. The keystore and key are 391 protected by the passwords you entered. The keystore contains 392 a single key, valid for 10000 days. The alias is a name that you — 393 will use later, to refer to this keystore when signing your application. </p> 394 395 <p>For more information about Keytool, see the documentation at 396 <a 397 href="http://java.sun.com/j2se/1.5.0/docs/tooldocs/#security"> 398 http://java.sun.com/j2se/1.5.0/docs/tooldocs/#security</a></p> 399 400 401 402 <h3 id="releasecompile">2. Compile the application in release mode</h3> 403 404 <p>In order to release your application to users, you must compile it in release mode. 405 In release mode, the compiled application is not signed by default and you will need 406 to sign it with your private key.</p> 407 408 <p class="caution"><strong>Caution:</strong> 409 You can not release your application unsigned, or signed with the debug key.</p> 410 411 <h4>With Eclipse</h4> 412 413 <p>To export an <em>unsigned</em> .apk from Eclipse, right-click the project in the Package 414 Explorer and select <strong>Android Tools</strong> > <strong>Export Unsigned Application 415 Package</strong>. Then specify the file location for the unsigned .apk. 416 (Alternatively, open your <code>AndroidManifest.xml</code> file in Eclipse, open 417 the <em>Overview</em> tab, and click <strong>Export an unsigned .apk</strong>.)</p> 418 419 <p>Note that you can combine the compiling and signing steps with the Export Wizard. See 420 <a href="#ExportWizard">Compiling and signing with Eclipse ADT</a>.</p> 421 422 <h4>With Ant</h4> 423 424 <p>If you are using Ant, you can enable release mode by using the <code>release</code> option 425 with the <code>ant</code> command. For example, if you are running Ant from the 426 directory containing your {@code build.xml} file, the command would look like this:</p> 427 428 <pre>ant release</pre> 429 430 <p>By default, the build script compiles the application .apk without signing it. The output file 431 in your project {@code bin/} will be <code><em><your_project_name></em>-unsigned.apk</code>. 432 Because the application .apk is still unsigned, you must manually sign it with your private 433 key and then align it using {@code zipalign}.</p> 434 435 <p>However, the Ant build script can also perform the signing 436 and aligning for you, if you have provided the path to your keystore and the name of 437 your key alias in the project's {@code build.properties} file. With this information provided, 438 the build script will prompt you for your keystore and alias password when you perform 439 <code>ant release</code>, it will sign the package and then align it. The final output 440 file in {@code bin/} will instead be 441 <code><em><your_project_name></em>-release.apk</code>. With these steps 442 automated for you, you're able to skip the manual procedures below (steps 3 and 4). 443 To learn how to specify your keystore and alias in the {@code build.properties} file, 444 see <a href="{@docRoot}guide/developing/other-ide.html#ReleaseMode">Developing In Other 445 IDEs: Building in release mode</a>.</p> 446 447 448 449 <h3 id="signapp">3. Sign your application with your private key</h3> 450 451 <p>When you have an application package that is ready to be signed, you can do sign it 452 using the Jarsigner tool. Make sure that you have Jarsigner available on your 453 machine, as described in <a href="#setup">Basic Setup</a>. Also, make sure that 454 the keystore containing your private key is available.</p> 455 456 <p>To sign your application, you run Jarsigner, referencing both the 457 application's .apk and the keystore containing the private key with which to 458 sign the .apk. The table below shows the options you could use. <p> 459 460 <table> 461 <tr> 462 <th>Jarsigner Option</th> 463 <th>Description</th> 464 </tr> 465 <tr> 466 <td><code>-keystore <keystore-name>.keystore</code></td><td>The name of 467 the keystore containing your private key.</td> 468 </tr> 469 <tr> 470 <td><code>-verbose</code></td><td>Enable verbose output.</td> 471 </tr> 472 <tr> 473 <td><code>-storepass <password></code></td><td><p>The password for the 474 keystore. </p><p>As a security precaution, do not include this option 475 in your command line unless you are working at a secure computer. 476 If not supplied, Jarsigner prompts you to enter the password. In this 477 way, your password is not stored in your shell history.</p></td> 478 </tr> 479 <tr> 480 <td><code>-keypass <password></code></td><td><p>The password for the private 481 key. </p><p>As a security precaution, do not include this option 482 in your command line unless you are working at a secure computer. 483 If not supplied, Jarsigner prompts you to enter the password. In this 484 way, your password is not stored in your shell history.</p></td> 485 </tr> 486 </table> 487 488 <p>Here's how you would use Jarsigner to sign an application package called 489 <code>my_application.apk</code>, using the example keystore created above. 490 </p> 491 492 <pre>$ jarsigner -verbose -keystore my-release-key.keystore 493 my_application.apk alias_name</pre> 494 495 <p>Running the example command above, Jarsigner prompts you to provide 496 passwords for the keystore and key. It then modifies the .apk 497 in-place, meaning the .apk is now signed. Note that you can sign an 498 .apk multiple times with different keys.</p> 499 500 <p>To verify that your .apk is signed, you can use a command like this:</p> 501 502 <pre>$ jarsigner -verify my_signed.apk</pre> 503 504 <p>If the .apk is signed properly, Jarsigner prints "jar verified". 505 If you want more details, you can try one of these commands:</p> 506 507 <pre>$ jarsigner -verify -verbose my_application.apk</pre> 508 509 <p>or</p> 510 511 <pre>$ jarsigner -verify -verbose -certs my_application.apk</pre> 512 513 <p>The command above, with the <code>-certs</code> option added, will show you the 514 "CN=" line that describes who created the key.</p> 515 516 <p class="note"><strong>Note:</strong> If you see "CN=Android Debug", this means the .apk was 517 signed with the debug key generated by the Android SDK. If you intend to release 518 your application, you must sign it with your private key instead of the debug 519 key.</p> 520 521 <p>For more information about Jarsigner, see the documentation at 522 <a href="http://java.sun.com/j2se/1.5.0/docs/tooldocs/#security"> 523 http://java.sun.com/j2se/1.5.0/docs/tooldocs/#security</a></p> 524 525 526 <h3 id="align">4. Align the final APK package</h3> 527 528 <p>Once you have signed the .apk with your private key, run <code>zipalign</code> on the file. 529 This tool ensures that all uncompressed data starts with a particular byte alignment, 530 relative to the start of the file. Ensuring alignment at 4-byte boundaries provides 531 a performance optimization when installed on a device. When aligned, the Android 532 system is able to read files with {@code mmap()}, even if 533 they contain binary data with alignment restrictions, rather than copying all 534 of the data from the package. The benefit is a reduction in the amount of 535 RAM consumed by the running application.</p> 536 537 <p>The <code>zipalign</code> tool is provided with the Android SDK, inside the 538 <code>tools/</code> directory. To align your signed .apk, execute:</p> 539 540 <pre>zipalign -v 4 <em>your_project_name</em>-unaligned.apk <em>your_project_name</em>.apk</pre> 541 542 <p>The {@code -v} flag turns on verbose output (optional). {@code 4} is the 543 byte-alignment (don't use anything other than 4). The first file argument is 544 your signed .apk (the input) and the second file is the destination .apk file (the output). 545 If you're overriding an existing .apk, add the {@code -f} flag.</p> 546 547 <p class="caution"><strong>Caution:</strong> Your input .apk must be signed with your 548 private key <strong>before</strong> you optimize the package with {@code zipalign}. 549 If you sign it after using {@code zipalign}, it will undo the alignment.</p> 550 551 <p>For more information, read about the 552 <a href="{@docRoot}guide/developing/tools/zipalign.html">zipalign</a> tool. 553 554 555 <h3 id="ExportWizard">Compile and sign with Eclipse ADT</h3> 556 557 <p>If you are using Eclipse with the ADT plugin, you can use the Export Wizard to 558 export a <em>signed</em> .apk (and even create a new keystore, 559 if necessary). The Export Wizard performs all the interaction with 560 the Keytool and Jarsigner for you, which allows you to sign the package using a GUI 561 instead of performing the manual procedures to compile, sign, 562 and align, as discussed above. Once the wizard has compiled and signed your package, 563 it will also perfom package alignment with {@code zipalign}. 564 Because the Export Wizard uses both Keytool and Jarsigner, you should 565 ensure that they are accessible on your computer, as described above 566 in the <a href=#setup">Basic Setup for Signing</a>.</p> 567 568 <p>To create a signed and aligned .apk in Eclipse:</p> 569 570 <ol> 571 <li>Select the project in the Package 572 Explorer and select <strong>File > Export</strong>.</li> 573 <li>Open the Android folder, select Export Android Application, 574 and click <strong>Next</strong>. 575 <p>The Export Android Application wizard now starts, which will 576 guide you through the process of signing your application, 577 including steps for selecting the private key with which to sign the .apk 578 (or creating a new keystore and private key).</p> 579 <li>Complete the Export Wizard and your application will be compiled, 580 signed, aligned, and ready for distribution.</li> 581 </ol> 582 583 584 585 <h2 id="secure-key">Securing Your Private Key</h2> 586 587 <p>Maintaining the security of your private key is of critical importance, both 588 to you and to the user. If you allow someone to use your key, or if you leave 589 your keystore and passwords in an unsecured location such that a third-party 590 could find and use them, your authoring identity and the trust of the user 591 are compromised. </p> 592 593 <p>If a third party should manage to take your key without your knowledge or 594 permission, that person could sign and distribute applications that maliciously 595 replace your authentic applications or corrupt them. Such a person could also 596 sign and distribute applications under your identity that attack other 597 applications or the system itself, or corrupt or steal user data. </p> 598 599 <p>Your reputation as a developer entity depends on your securing your private 600 key properly, at all times, until the key is expired. Here are some tips for 601 keeping your key secure: </p> 602 603 <ul> 604 <li>Select strong passwords for the keystore and key.</li> 605 <li>When you generate your key with Keytool, <em>do not</em> supply the 606 <code>-storepass</code> and <code>-keypass</code> options at the command line. 607 If you do so, your passwords will be available in your shell history, 608 which any user on your computer could access.</li> 609 <li>Similarly, when signing your applications with Jarsigner, 610 <em>do not</em> supply the <code>-storepass</code> and <code>-keypass</code> 611 options at the command line. </li> 612 <li>Do not give or lend anyone your private key, and do not let unauthorized 613 persons know your keystore and key passwords.</li> 614 </ul> 615 616 <p>In general, if you follow common-sense precautions when generating, using, 617 and storing your key, it will remain secure. </p>