Android Sdk Cryptographic Key Generation

  

Sep 08, 2019  Device Serial (requires dangerous permission SDK 25) Sim-ID/ICCID (if changing the sim should/can invalidate the data) Android OS image build fingerprint (if you want to invalidate the data after OS update) Key Derivation Process. The cryptographic key used to encrypt the data is. Password-based encryption (PBE) ciphers that require an initialization vector (IV) can obtain it from the key, if it's suitably constructed, or from an explicitly-passed IV. When passing a PBE key that doesn't contain an IV and no explicit IV, the PBE ciphers on Android currently assume an IV of zero. Sep 27, 2019  Android SDK provides mechanisms for specifying secure key generation and use. Android 6.0 (API level 23) introduced the KeyGenParameterSpec class that can be used to ensure the correct key usage in the application. Here's an example of using AES/CBC/PKCS7Padding on API 23+. Password-based encryption (PBE) ciphers that require an initialization vector (IV) can obtain it from the key, if it's suitably constructed, or from an explicitly-passed IV. When passing a PBE key that doesn't contain an IV and no explicit IV, the PBE ciphers on Android currently assume an IV of zero.

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Creating and managing keys is an important part of the cryptographic process. Symmetric algorithms require the creation of a key and an initialization vector (IV). The key must be kept secret from anyone who should not decrypt your data. The IV does not have to be secret, but should be changed for each session. Asymmetric algorithms require the creation of a public key and a private key. /java-generate-all-key-values-for-a-map.html. The public key can be made public to anyone, while the private key must known only by the party who will decrypt the data encrypted with the public key. This section describes how to generate and manage keys for both symmetric and asymmetric algorithms.

Doesn’t Android. Key Generation. The AndroidKeyStore is a container which stores cryptographic keys in the TEE or StrongBox, making them hard to extract. The build process is similar to the debug build process and can be done using JDK and Android SDK tools. The testing tasks serve as a final check, ensuring that your application performs as expected under real-world conditions. Preparing for release is a required development task and is the first step in the. Cryptographic keys.

Symmetric Keys

The symmetric encryption classes supplied by the .NET Framework require a key and a new initialization vector (IV) to encrypt and decrypt data. Whenever you create a new instance of one of the managed symmetric cryptographic classes using the parameterless constructor, a new key and IV are automatically created. Anyone that you allow to decrypt your data must possess the same key and IV and use the same algorithm. Generally, a new key and IV should be created for every session, and neither the key nor IV should be stored for use in a later session.

Android Sdk Cryptographic Key Generation Download

To communicate a symmetric key and IV to a remote party, you would usually encrypt the symmetric key by using asymmetric encryption. Sending the key across an insecure network without encrypting it is unsafe, because anyone who intercepts the key and IV can then decrypt your data. For more information about exchanging data by using encryption, see Creating a Cryptographic Scheme.

The following example shows the creation of a new instance of the TripleDESCryptoServiceProvider class that implements the TripleDES algorithm.

When the previous code is executed, a new key and IV are generated and placed in the Key and IV properties, respectively.

Sometimes you might need to generate multiple keys. In this situation, you can create a new instance of a class that implements a symmetric algorithm and then create a new key and IV by calling the GenerateKey and GenerateIV methods. The following code example illustrates how to create new keys and IVs after a new instance of the symmetric cryptographic class has been made.

When the previous code is executed, a key and IV are generated when the new instance of TripleDESCryptoServiceProvider is made. Another key and IV are created when the GenerateKey and GenerateIV methods are called.

Asymmetric Keys

The .NET Framework provides the RSACryptoServiceProvider and DSACryptoServiceProvider classes for asymmetric encryption. These classes create a public/private key pair when you use the parameterless constructor to create a new instance. Asymmetric keys can be either stored for use in multiple sessions or generated for one session only. While the public key can be made generally available, the private key should be closely guarded.

A public/private key pair is generated whenever a new instance of an asymmetric algorithm class is created. After a new instance of the class is created, the key information can be extracted using one of two methods:

  • The ToXmlString method, which returns an XML representation of the key information.

  • The ExportParameters method, which returns an RSAParameters structure that holds the key information.

Both methods accept a Boolean value that indicates whether to return only the public key information or to return both the public-key and the private-key information. An RSACryptoServiceProvider class can be initialized to the value of an RSAParameters structure by using the ImportParameters method.

Asymmetric private keys should never be stored verbatim or in plain text on the local computer. If you need to store a private key, you should use a key container. For more on how to store a private key in a key container, see How to: Store Asymmetric Keys in a Key Container.

The following code example creates a new instance of the RSACryptoServiceProvider class, creating a public/private key pair, and saves the public key information to an RSAParameters structure.

See also

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To prepare your application for release, you need to configure, build, and test a releaseversion of your application. The configuration tasks are straightforward, involving basic codecleanup and code modification tasks that help optimize your application. The build process issimilar to the debug build process and can be done using JDK and Android SDK tools. The testingtasks serve as a final check, ensuring that your application performs as expected under real-worldconditions. When you are finished preparing your application for release you have a signedAPK file, which you can distribute directly to users or distribute through anapplication marketplace such as Google Play.

This document summarizes the main tasks you need to perform to prepare your application forrelease. The tasks that are described in this document apply to all Android applications regardlesshow they are released or distributed to users. If you are releasing your application through GooglePlay, you should also read the Google Play launch checklist.

Note: As a best practice, your application should meet all of yourrelease criteria for functionality, performance, and stability before you perform the tasks outlinedin this document.

Figure 1. Preparing for release is a required developmenttask and is the first step in the publishing process.

Introduction

To release your application to users you need to create a release-ready package that users caninstall and run on their Android-powered devices. The release-ready package contains the samecomponents as the debug APK file — compiled source code, resources, manifestfile, and so on — and it is built using the same build tools. However, unlike the debugAPK file, the release-ready APK file is signed with your own certificateand it is optimized with the zipalign tool.

Figure 2. You perform five main tasks to prepare your application for release.

The signing and optimization tasks are usually seamless if you are building your application withAndroid Studio. For example, you can use Android Studio with the Gradle build files to compile, sign,and optimize your application all at once. You can also configure the Gradle build files to do thesame when you build from the command line. For more details about using the Gradle build files, seethe Build System guide.

To prepare your application for release you typically perform five main tasks (see figure 2).Each main task may include one or more smaller tasks depending on how you are releasing yourapplication. For example, if you are releasing your application through Google Play you may wantto add special filtering rules to your manifest while you are configuring your application forrelease. Similarly, to meet Google Play publishing guidelines you may have to prepare screenshotsand create promotional text while you are gathering materials for release.

You usually perform the tasks listed in figure 2 after you have throroughly debugged and testedyour application. The Android SDK contains several tools to help you test and debug your Androidapplications. For more information, see the Debugging and Testing sections in the Dev Guide.

Gathering materials and resources

To begin preparing your application for release you need to gather several supporting items. At aminimum this includes cryptographic keys for signing your application and an application icon. Youmight also want to include an end-user license agreement.

Cryptographic keys

The Android system requires that each installed application be digitally signed with acertificate that is owned by the application's developer (that is, a certificate for which thedeveloper holds the private key). The Android system uses the certificate as a means of identifyingthe author of an application and establishing trust relationships between applications. Thecertificate that you use for signing does not need to be signed by a certificate authority; theAndroid system allows you to sign your applications with a self-signed certificate. To learn aboutcertificate requirements, see Signing YourApplications.

Important: Your application must be signed with a cryptographickey whose validity period ends after 22 October 2033.

You may also have to obtain other release keys if your application accesses a service or uses athird-party library that requires you to use a key that is based on your private key.

Application icon

Be sure you have an application icon and that it meets the recommended icon guidelines. Yourapplication's icon helps users identify your application on a device's Homescreen and in the Launcher window. It also appears in Manage Applications, My Downloads, andelsewhere. In addition, publishing services such as Google Play display your icon to users.

Note: If you are releasing your application on Google Play, youneed to create a high resolution version of your icon. See GraphicAssets for your Application for more information.

End-user license agreement

Consider preparing an End User License Agreement (EULA) for your application. A EULA can helpprotect your person, organization, and intellectual property, and we recommend that you provide onewith your application.

Miscellaneous materials

You might also have to prepare promotional and marketing materials to publicize your application.For example, if you are releasing your application on Google Play you will need to prepare somepromotional text and you will need to create screenshots of your application. For moreinformation, seeGraphic Assets for your Application

Configuring Your application for release

After you gather all of your supporting materials you can start configuring your applicationfor release. This section provides a summary of the configuration changes we recommend that you maketo your source code, resource files, and application manifest prior to releasing your application.Although most of the configuration changes listed in this section are optional, they areconsidered good coding practices and we encourage you to implement them. In some cases,you may have already made these configuration changes as part of your development process.

Choose a good package name

Make sure you choose a package name that is suitable over the life of your application. Youcannot change the package name after you distribute your application to users. You can set thepackage name in application's manifest file. For more information, see the package attributedocumentation.

Turn off logging and debugging

Make sure you deactivate logging and disable the debugging option before you build yourapplication for release. You can deactivate logging by removing calls toLog methods in your source files. You can disable debugging by removing theandroid:debuggable attribute from the <application> tag in yourmanifest file, or by setting the android:debuggable attribute tofalse in your manifest file. Also, remove any log files or static test files thatwere created in your project.

Also, you should remove all Debug tracing calls that youadded to your code, such as startMethodTracing() andstopMethodTracing() method calls.

Important: Ensure that you disable debugging foryour app if using WebView to display paid for content or if using JavaScriptinterfaces, since debugging allows users to inject scripts and extract content using ChromeDevTools. To disable debugging, use theWebView.setWebContentsDebuggingEnabled()method.

Clean up your project directories

Clean up your project and make sure it conforms to the directory structure described in Android Projects.Leaving stray or orphaned files in your project can prevent your application from compiling andcause your application to behave unpredictably. At a minimum you should do the following cleanuptasks:

  • Review the contents of your jni/, lib/, and src/ directories. The jni/ directory should contain only source files associated with the Android NDK, such as .c, .cpp, .h, and .mk files. The lib/ directory should contain only third-party library files or private library files, including prebuilt shared and static libraries (for example, .so files). The src/ directory should contain only the source files for your application (.java and .aidl files). The src/ directory should not contain any .jar files.
  • Check your project for private or proprietary data files that your application does not use and remove them. For example, look in your project's res/ directory for old drawable files, layout files, and values files that you are no longer using and delete them.
  • Check your lib/ directory for test libraries and remove them if they are no longer being used by your application.
  • Review the contents of your assets/ directory and your res/raw/ directory for raw asset files and static files that you need to update or remove prior to release.

Android Sdk Cryptographic Key Generation 1

Review and update your manifest and Gradle build settings

Verify that the following manifest and build files items are set correctly:

  • <uses-permission> element

    You should specify only those permissions that are relevant and required for your application.

  • android:icon and android:label attributes

    You must specify values for these attributes, which are located in the <application> element.

  • android:versionCode and android:versionName attributes.

    We recommend that you specify values for these attributes, which are located in the <manifest> element. For more information see Versioning your Application.

There are several additional manifest or build file elements that you can set if you are releasing yourapplication on Google Play. For example, the android:minSdkVersion andandroid:targetSdkVersion attributes, which are located in the <uses-sdk> element. For moreinformation about these and other Google Play settings, see Filters on Google Play.

Address compatibility issues

Android provides several tools and techniques to make your application compatible with a widerange of devices. To make your application available to the largest number of users, considerdoing the following:

  • Add support for multiple screen configurations

    Make sure you meet the best practices for supporting multiple screens. By supporting multiple screen configurations you can create an application that functions properly and looks good on any of the screen sizes supported by Android.

  • Optimize your application for Android tablet devices.

    If your application is designed for devices older than Android 3.0, make it compatible with Android 3.0 devices by following the guidelines and best practices described in Optimizing Apps for Android 3.0 .

  • Consider using the Support Library

    If your application is designed for devices running Android 3.x, make your application compatible with older versions of Android by adding the Support Library to your application project. The Support Library provides static support libraries that you can add to your Android application, which enables you to use APIs that are either not available on older platform versions or use utility APIs that are not part of the framework APIs.

Update URLs for servers and services

If your application accesses remote servers or services, make sure you are using the productionURL or path for the server or service and not a test URL or path.

Android Sdk Cryptographic Key Generation Software

Implement licensing (if you are releasing on Google Play)

If you are releasing a paid application through Google Play, consider adding support forGoogle Play Licensing. Licensing lets you control access to your application based on whether thecurrent user has purchased it. Using Google Play Licensing is optional even if you arereleasing your app through Google Play.

For more information about Google Play Licensing Service and how to use it in yourapplication, see Application Licensing.

Building Your application for release

After you finish configuring your application you can build it into a release-readyAPK file that is signed and optimized. The JDK includes the tools for signing theAPK file (Keytool and Jarsigner); the Android SDK includes the tools for compiling andoptimizing the APK file. If you are using Android Studio or you are usingthe Gradle build system from the command line, you can automate the entire build process.For more information about configuring Gradle builds, seeConfiguring Gradle Builds.

Building with Android Studio

You can use the Gradle build system, integrated with Android Studio to build a release-readyAPK file that is signed with your private key and optimized. To learn how to setup andrun builds from Android Studio, seeBuilding and Running from Android Studio.

The build process assumes that you have a certificate and private keysuitable for signing your application. If you do not have a suitable certificate and private key,Android Studio can help you generate one. For more information about the signing process, seeSigning Your Applications.

Preparing external servers and resources

If your application relies on a remote server, make sure the server is secure and that it isconfigured for production use. This is particularly important if you are implementing in-app billing in your application and you areperforming the signature verification step on a remote server.

Also, if your application fetches content from a remote server or a real-time service (such as acontent feed), be sure the content you are providing is up to date and production-ready.

Testing your application for release

Testing the release version of your application helps ensure that your application runs properlyunder realistic device and network conditions. Ideally, you should test your application on at leastone handset-sized device and one tablet-sized device to verify that your user interface elements aresized correctly and that your application's performance and battery efficiency are acceptable.

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As a starting point for testing, seeWhat to Test. This article providesa summary of common Android situations that you should consider when you are testing. When you aredone testing and you are satisfied that the release version of your applicationbehaves correctly, you can release your application to users. For more information, seeReleasing YourApplication to Users. If you are publishing your application on Google Play, seeLaunch Checklistfor Google Play.