As a security measure, Android requires that apps be signed in order to be installed. Signing an app first requires creating keystores. A keystore is a storage mechanism for security certificates. A public key certificate is used to sign an APK before deployment to services like the Google Play Store. Signing the APK in this fashion allows Google to provide a high level of certainty that future updates to your APK of the same app come from you and not some malicious third party.
- Generating A New Private Key Android Free
- Advantages Of Private Key Encryption
- Generating A New Private Key Android App
Considerations
I'm looking for a way to generate Ethereum private keys and public keys inside an Android app. I've scavenged the web and ultimately decided to tear apart the code to myetherwallet and import the s. Feb 06, 2019 aws-sdk-android-samples / AndroidPubSub / src / com / amazonaws / demo / androidpubsub / PubSubActivity.java Find file Copy path desokroshan Update README and fix a bug in off-device keystore usecase ( #302 ) d3a1383 Feb 5, 2019.
There are some things you will need to consider before first deploying your Android app. Primary among these is the expected lifespan of your app. You will not be able to deploy the same app signed by another key at any point in the near future. Android, as well as Google Play, enforces the use of the same key for updates to an APK. If you need to sign your app with another key for any reason, you will have to deploy the app with a new package name. Any ratings your app had on Google Play will be lost. You will also lose touch with your user base unless you have notified them in some way to expect the existing app to be obsolete.
Creating keystores
After you have decided on an app’s lifespan, you’ll want to generate your keystore. Java includes a tool for just this purpose:
keytool
. keytool
is located in your Java JDK installation and should be on your path for the purposes of this article. keytool
will quickly generate a public/private key pair and store them in a keystore for you after you answer a few simple questions.keytool
has a number of commands. The most common command used for signing Android builds -genkeypair
, commonly abbreviated -genkey
. The other commands may be useful to you, but uncommonly so. Again, there are lots of options for this keytool
command. The primary -genkey
options we are concerned with are in the table below with a brief description:Generating A New Private Key Android Free
-keystore | Filename of the generated keystore |
-alias | Keypair alias name |
-keyalg | Algorithm used to generate keypair |
-keysize | Keypair size, in bits |
-validity | Keypair validity duration, in days |
In other words, running the command
keytool -genkey -v -keystore release.keystore -alias example -keyalg RSA -keysize 2048 -validity 10000
would result in a keystore file called
release.keystore
which contained an RSA-2048 public/private keypair by the alias name of example
and validity of 10,000 days (more than 27 years).Before running this command, you’ll want to decide on strong passwords for the keystore and key. You’ll need both of these passwords to sign an APK — they can be the same password if you’re into that kind of thing. The tool will also collect some metadata like your name and organization, but all of that is optional.
Related: Backgrounding Instead of Finishing the Root Activity on Android
Signing your APK
- Sign with Gradle
After running the command you’ll be the proud owner of a brand new Java Keystore. You probably want to set up your project to use the keystore to sign your APK, so let’s have a look at that.
If you’re using gradle to build your Android project, you will create a
android.signingConfig
and associate it with one or more android.buildTypes
. The two passwords, keystore name, and alias name will all be needed in order to sign an APK. You can handle this in at least a few different ways. The simplest is to enter the relevant information directly into your gradle build script:If you want to control access to the passwords you can move the information out of the build.gradle file and put it in your local environment or in a properties file to load at build time. To maintain security and control of the information, it’s likely that you would not want to check the keystore properties file into your source control.
Here is an example [from Google] of how to load the information from a file that would be located in your app’s root directory with the project level build.gradle file:
keystore.properties would contain (in this example):
If you prefer the environment variable method, create a script to add the variables to your environment and try something like this:
There are some trade-offs to both of these methods. Figure out what works best for your organization’s methodology and use that one. For the environment variable method, for example, you have to load these variables into your environment somehow. This is less than ideal if you want to generate a signed APK with Android Studio.
- Sign manually
If you prefer to sign your APK manually instead of as part of the build process, you’ll want to use
apksigner
, located at {ANDROID_SDK_DIRECTORY}/build-tools/{BUILD_TOOLS_VERSION}/apksigner
Shogun total war product key generator. for build-tools revision 24.0.3 or higher. apksigner
uses the public/private key pair stored in your app’s keystore to generate a public key certificate. apksigner
then attaches that certificate to the APK. After this is accomplished, the APK is associated with that private key in a unique way. The Android gradle plugin will handle this for you if you configure your build.gradle file with all of the necessary information, as shown above.You’ll want to
zipalign
your APK, zipalign
will ensure that your app’s uncompressed data starts at a predictable offset inside the APK. zipalign
ed APKs are required to publish to the Google Play store.After your APK is
zipalign
ed, sign it using apksigner
:You will be prompted at the command line to enter the password for your keystore.
If your keystore and key passwords differ, you’re in for a treat! Using the command above, you will be asked for the keystore password, but will not be asked for the key password. Entering either password results in exceptions and you won’t be having a good time. You’ll need to tell
apksigner
that you want to specify each password individually. Apparently, this is supposed to be the default behavior, but it hasn’t worked for me. To force apksigner
to ask you for the keystore and key password independently, use the --ks-pass
and --key-pass
options. Following each option with stdin
will tell apksigner
to capture the password from you at the command line.I hope this has educated you a bit more about how creating keystores and signing an Android APK works.
More in Engineering
-->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. 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.
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.
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 division cd key generator. 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.
Advantages Of Private Key Encryption
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.