/lib directory - H3: Add apksigner.jar to your PATH environment variable - H2: How to use apksigner.jar to sign an APK file - H3: Generate a keystore and a key pair using keytool - H3: Sign the APK file using apksigner sign command - H3: Verify the signature using apksigner verify command - H2: Conclusion - H3: Summary of the main points - H3: Call to action and resources for further learning - H2: FAQs - H3: What are the benefits of using apksigner over jarsigner? - H3: How can I rotate my signing keys using apksigner? - H3: How can I sign an app bundle using apksigner? - H3: How can I troubleshoot common errors with apksigner? - H3: How can I automate the signing process with apksigner? Article with HTML formatting: How to download apksigner.jar
If you are developing Android apps, you might have heard of apksigner.jar, a tool that lets you sign your APK files with a digital certificate. Signing your APK files is essential for distributing your apps to users, as it ensures the authenticity and integrity of your app. In this article, you will learn what apksigner.jar is, how to get it from the Android SDK, and how to use it to sign your APK files.
download apksigner.jar
What is apksigner.jar and why do you need it?
apksigner.jar is a tool for signing APK files
An APK file is a package that contains all the files and resources of your Android app. Before you can install or update an APK file on a device, you need to sign it with a private key and a certificate. Signing an APK file proves that you are the author of the app and that no one has tampered with it.
apksigner.jar is a tool that helps you sign your APK files using standard tools from the Android SDK and the JDK. It supports different signature schemes, such as v1 (JAR signing), v2 (APK Signature Scheme v2), and v3 (APK Signature Scheme v3). It also lets you verify the signature of an APK file and rotate your signing keys.
Signing APK files is necessary for distributing Android apps
Signing your APK files is not only a good security practice, but also a requirement for distributing your apps to users. For example, if you want to publish your app on Google Play, you need to sign your app with an upload key, which Google uses to verify your identity. Google then signs your app with an app signing key, which is used to authenticate your app on devices.
Signing your APK files also ensures that users can install updates to your app without any problems. If you change your signing key or use an inconsistent signature scheme, users might encounter installation errors or lose their app data.
How to get apksigner.jar from the Android SDK
Install Android Studio and the Android SDK Build Tools
To use apksigner.jar, you need to have Android Studio and the Android SDK Build Tools installed on your computer. Android Studio is an integrated development environment (IDE) that helps you create and test Android apps. The Android SDK Build Tools are a collection of tools that help you compile, debug, and package your apps.
You can download Android Studio from . After installing Android Studio, you can use the SDK Manager to download and update the Android SDK Build Tools. You can access the SDK Manager from the Tools menu in Android Studio.
Locate apksigner.jar in the build-tools//lib directory
After installing the Android SDK Build Tools, you can find apksigner.jar in the build-tools//lib directory, where is the version number of the Build Tools you have installed. For example, if you have installed Build Tools 31.0.0, you can find apksigner.jar in the build-tools/31.0.0/lib directory.
Add apksigner.jar to your PATH environment variable
To make it easier to use apksigner.jar from the command line, you can add it to your PATH environment variable. The PATH environment variable is a list of directories that your operating system searches for executable files when you type a command.
To add apksigner.jar to your PATH on Windows, you can follow these steps:
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Open the Control Panel and click on System and Security.
Click on System and then on Advanced system settings.
Click on Environment Variables and select Path from the System variables list.
Click on Edit and then on New.
Type or paste the path to the directory where apksigner.jar is located, such as C:\Users\\AppData\Local\Android\Sdk\build-tools\31.0.0\lib.
Click on OK and then on OK again to save the changes.
To add apksigner.jar to your PATH on Mac or Linux, you can edit your .bash_profile or .bashrc file and append the following line:
export PATH=$PATH:
For example, if apksigner.jar is located in /Users//Library/Android/sdk/build-tools/31.0.0/lib, you can add this line:
export PATH=$PATH:/Users//Library/Android/sdk/build-tools/31.0.0/lib
Save the file and restart your terminal for the changes to take effect.
How to use apksigner.jar to sign an APK file
Generate a keystore and a key pair using keytool
To sign an APK file, you need a keystore and a key pair. A keystore is a file that stores one or more private keys and their associated certificates. A key pair consists of a private key and a public key that are mathematically linked. The private key is used to sign the APK file, while the public key is embedded in the certificate that verifies the signature.
You can use keytool, a tool from the JDK, to generate a keystore and a key pair. To do so, you can run the following command:
keytool -genkeypair -keystore .jks -alias -keyalg RSA -keysize 2048 -validity 10000 -dname "CN=, OU=, O=, L=, S=, C=" -storepass -keypass
In this command, you need to replace the following parameters with your own values:
: The name of the keystore file, such as myapp.jks.
: The name of the key pair, such as myappkey.
: The name of the app or the developer, such as My App or John Doe.
: The name of the unit or department within the organization, such as Development or Engineering.
: The name of the organization or company, such as My Company or ABC Inc.
: The name of the city where the organization is located, such as New York or London.
: The name of the state or province where the organization is located, such as NY or ON.
: The two-letter country code where the organization is located, such as US or CA.
: The password for accessing the keystore, such as myapp1234.
: The password for accessing the key pair, which can be the same as or different from the keystore password, such as myapp1234.
This command will create a keystore file with the specified name and a key pair with the specified alias in the current directory. You will also be asked to enter some information about the certificate, such as the validity period, the name, and the organization. You can accept the default values or enter your own.
Sign the APK file using apksigner sign command
Once you have a keystore and a key pair, you can use apksigner to sign your APK file. To do so, you can run the following command:
apksigner sign --ks .jks --ks-key-alias --ks-pass pass: --key-pass pass: --out .apk .apk
In this command, you need to replace the following parameters with your own values:
: The name of the keystore file, such as myapp.jks.
: The name of the key pair, such as myappkey.
: The password for accessing the keystore, such as myapp1234.
: The password for accessing the key pair, such as myapp1234.
: The name of the signed APK file, such as myapp-signed.apk.
: The name of the unsigned APK file, such as myapp-unsigned.apk.
This command will sign the APK file using the specified keystore and key pair and output a signed APK file with the specified name in the current directory. By default, it will use the v1 and v2 signature schemes. You can specify a different signature scheme using the --v1-signing-enabled, --v2-signing-enabled, or --v3-signing-enabled options.
Verify the signature using apksigner verify command
After signing your APK file, you can use apksigner to verify that the signature is valid and meets the requirements for installing and updating your app. To do so, you can run the following command:
apksigner verify --verbose --print-certs .apk
In this command, you need to replace with the name of your signed APK file, such as myapp-signed.apk.
This command will check the signature of your APK file and print out some information about it, such as the signature scheme, the certificate details, and any warnings or errors. If the signature is valid and meets the requirements, you will see a message like this:
Verifies Verified using v1 scheme (JAR signing): true Verified using v2 scheme (APK Signature Scheme v2): true Verified using v3 scheme (APK Signature Scheme v3): true Number of signers: 1 Signer #1 certificate DN: CN=My App, OU=Development, O=My Company, L=New York, S=NY, C=US Signer #1 certificate SHA-256 digest: 1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef Signer #1 certificate SHA-1 digest: 1234567890abcdef12345678 Signer #1 certificate MD5 digest: 1234567890abcdef Signer #1 key algorithm: RSA Signer #1 key size (bits): 2048 Signer #1 public key SHA-256 digest: 1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef Signer #1 public key SHA-1 digest: 1234567890abcdef12345678 Signer #1 public key MD5 digest: 1234567890abcdef
Conclusion
Summary of the main points
In this article, you have learned how to download apksigner.jar from the Android SDK and how to use it to sign your APK files. You have also learned why signing your APK files is important for distributing your apps to users and ensuring their security and compatibility. Signing your APK files with apksigner.jar is a simple and effective way to prepare your apps for release.
Call to action and resources for further learning
If you want to learn more about apksigner.jar and how to use it for signing your apps, you can check out these resources:
: The official documentation for apksigner.jar from Google.</li Best practices for using apksigner
Using apksigner to sign your APK files is a simple and effective way to prepare your apps for release, but there are some best practices that you should follow to ensure the security and compatibility of your apps. Here are some tips and recommendations for using apksigner:
Use the latest version of apksigner from the Android SDK Build Tools. The latest version supports the most recent signature schemes and features, such as APK Signature Scheme v4, which enables faster app installation and verification on Android 11 and higher. You can update the Android SDK Build Tools using the SDK Manager in Android Studio.
Use a separate upload key for signing your app bundle before uploading it to Google Play. This way, you can keep your app signing key more secure and have the option to reset your upload key if it gets lost or compromised. You can generate a new upload key using keytool and register it with Google Play using the App signing by Google Play page in the Play Console.
Use a strong password and a secure location for your keystore and key files. Your keystore and key files contain sensitive information that could be used to impersonate you or tamper with your apps. You should protect them with a strong password that is not easy to guess or crack, and store them in a secure location that is not accessible by others. You should also back up your keystore and key files in case they get corrupted or deleted.
Use the highest minSdkVersion value that is compatible with your app. The minSdkVersion value determines the lowest Android framework API level that apksigner uses to confirm that the APK's signature will be verified. Higher values allow apksigner to use stronger security parameters when signing the app, but limit the app's availability to devices running more recent versions of Android. By default, apksigner uses the value of the minSdkVersion attribute from the app's manifest file, but you can override it using the --min-sdk-version option.
Verify the signature of your APK file after signing it. You can use apksigner verify command to check that the signature of your APK file is valid and meets the requirements for installing and updating your app on different versions of Android. You can also use the --verbose and --print-certs options to get more information about the signature, such as the signature scheme, the certificate details, and any warnings or errors.
FAQs
What are the benefits of using apksigner over jarsigner?
jarsigner is another tool from the JDK that can be used to sign APK files using the v1 signature scheme. However, apksigner has some advantages over jarsigner, such as:
apksigner supports newer signature schemes, such as v2, v3, and v4, which offer better security and performance than v1.
apksigner can sign APK files that have been aligned with zipalign, which optimizes the APK file for faster loading and running on devices. jarsigner cannot sign aligned APK files.
apksigner can verify the signature of an APK file and check for any issues or warnings that might affect the installation or update of the app. jarsigner cannot verify the signature of an APK file.
How can I rotate my signing keys using apksigner?
Rotating your signing keys means changing your private key and certificate without affecting the app's compatibility or security. This can be useful if your key gets compromised or expires, or if you want to use a stronger key algorithm or size. To rotate your signing keys using apksigner, you can follow these steps:
Generate a new keystore and key pair using keytool with a different alias and certificate than your old one.
Sign your APK file with both your old and new key pairs using apksigner sign command with the --next-signer option.
Verify the signature of your APK file using apksigner verify command with the --min-sdk-version option set to 24 or higher.
This will create a signature that contains both your old and new certificates, which will allow devices running Android 7.0 (API level 24) or higher to accept the new certificate as a valid update. Devices running lower versions of Android will still use the old certificate to verify the app.
How can I sign an app bundle using apksigner?
An app bundle is a file format that contains all the files and resources of your app in a compressed form. It allows Google Play to generate optimized APK files for different device configurations, such as screen size, language, and architecture. To sign an app bundle using apksigner, you can use the same command as for signing an APK file, but with the --v4-signing-enabled true option. For example:
apksigner sign --ks .jks --ks-key-alias --ks-pass pass: --key-pass pass: --out .aab --v4-signing-enabled true .aab
This will sign your app bundle using the v4 signature scheme, which is required for app bundles. You can also use other signature schemes, such as v1, v2, or v3, but they are not mandatory for app bundles.
How can I troubleshoot common errors with apksigner?
Sometimes, you might encounter some errors or issues when using apksigner to sign or verify your APK files. Here are some common errors and how to fix them:
ErrorCauseSolution
Failed to load signer "signer #1"The keystore or key password is incorrect or missing.Make sure you enter the correct password for your keystore and key pair using the --ks-pass and --key-pass options.
No key with alias '' found in keystore .jksThe key alias is incorrect or missing.Make sure you enter the correct alias for your key pair using the --ks-key-alias option.
The APK's minSdkVersion is too low (x). It must be at least y.The minSdkVersion value of your app is lower than the minimum required by the signature scheme.Increase the minSdkVersion value of your app in the manifest file or override it using the --min-sdk-version option.
The APK's signatures do not match across signer #1's certificates.The APK file has been signed with different certificates that have conflicting attributes.Make sure you use consistent certificates when signing your APK file with multiple key pairs.
The APK is not zip aligned.The APK file has not been aligned with zipalign, which optimizes the APK file for faster loading and running on devices.Use zipalign to align your APK file before signing it or use the --v1-signing-enabled false option to disable v1 signature scheme.
How can I automate the signing process with apksigner?
If you want to automate the signing process with apksigner, you can use a Gradle task or a shell script to run the apksigner commands. Gradle is a build automation tool that helps you manage the dependencies, tasks, and outputs of your project. A shell script is a file that contains a series of commands that can be executed by a shell program, such as Bash or PowerShell.
To use a Gradle task to sign your APK file with apksigner, you can add the following code to your app's build.gradle file:
android ... signingConfigs release storeFile file(".jks") storePassword "" keyAlias "" keyPassword "" buildTypes release signingConfig signingConfigs.release
This code will create a signing configuration named release and assign it to the release build type. You need to replace the parameters with your own values. You can then use the assembleRelease task to build and sign your APK file with apksigner.
To use a shell script to sign your APK file with apksigner, you can create a file named sign.sh and add the following code:
#!/bin/bash apksigner sign --ks .jks --ks-key-alias --ks-pass pass: --key-pass pass: --out .apk .apk apksigner verify --verbose --print-certs .apk
This code will sign and verify your APK file with apksigner using the specified parameters. You need to replace the parameters with your own values. You can then run the script from the command line using the following command:
bash sign.sh 44f88ac181
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