Issue and verify standalone license keys unlocking paid features, without a license server.
The library is compatible with Android SDK version 21 and higher.
It comes with its own java.util.Base64.
A key issued by this library looks like this:
eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJkb3NsYXZhMDMwQGdtYWlsLmNvbSIsImYiOls1XSwiaXNzIjoicHAtbGljZW5zZS5yYWRpb2tvdC5jb20udWEiLCJodyI6ImRjZmQzNzQ1NWU4ZjUzNmExMTQzNjA4MDMxNTk4ZWYwNzQ1MmQ2MmQyODEzOWQyMGZhMjlkOWRmZmYwZDU1NmIifQ.It1g030OSYLZ2TOwmqui69ZeJFpqkE7ACW9mAoZhIAoSDMagozretJMZW9O4fu6dd6ga4DmOhzScPv6GCgYLXGphrJ0DgWZpXeO6PFH7R1HhpiMIzUwQMK8wSWnf1euPbY2j5RWa-8Bv9g-8Ktcn12lp3kDtBi3LXxW7VySGgLB07WUvte50m5aL3fuaeV3g6hf_z9UJ2n4NWIX7Esqy63z0wOO452sr83G0I292N_AK_DSIRRE3NNNLsNzOonKVOc1-zYPslb1qMOPjUOGi4WFhSM_bArBH661p35OHzRaS3Jrh2KB_GKA9Tn5uYzNZMFEVQpus0DVqKUMyhmuk
It is indeed a JWT signed with RSA, so it can only be issued by the owner of the secret yet validated by anyone.
The key carries the following attributes:
- Issuer – the issuer of this key. Can be an email, a domain name or other identifier
- Subject – a user to whom this key is issued. Can be an email or other identifier
- Features – a set of integer indices of features (feature flags) the key activates
- Hardware – an identifier of the hardware this key is tied to
- Expiration date – an optional attribute specifying the date at which this key expires, hence the features must be deactivated
Start with OfflineLicenseKeys.jwt and follow the method docs.
Usage example can be found in JwtLicenseKeyFactoryTest and JwtLicenseKeyVerifyingReaderTest
| Apps using Offline License Key | |
|---|---|
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Gallery for PhotoPrism is an Android app which uses the library to activate extensions |
Step 1. Ensure you have JitPack repo added to your project build.gradle file:
dependencyResolutionManagement {
repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
repositories {
mavenCentral()
maven { url 'https://jitpack.io' }
}
}Step 2. Add the dependency
dependencies {
implementation 'ua.com.radiokot:offline-license-key:1.0.0'
// JitPack occasinally fails to resolve this package.
// If this happens, try 'com.github.Radiokot:offline-license-key' instead.
}I reject the concept of intellectual property. Claiming ownership over information that can be replicated perfectly and endlessly is inherently flawed. Consequently, any efforts to uphold such form of ownership inevitably result in some people gaining unjustifiable control over other's tangible resources, such as computers, printing equipment, construction materials, etc. When talking specifically about source code licensing – without a state violently enforcing copyright monopolies, it would be ludicrous to assume that a mere text file in a directory enables someone to restrict processing copies of this information by others on their very own computers. However, there is such a file in this repository bearing the GPLv3 license. Why?
One would expect someone with such an attitude to not use the license at all, use a permissive license, or explicitly unlicense. But for me, to do so is to voluntarily limit my means of defense. To act as a gentleman with those who readily exploit state violence against you is to lose. In a world where copyright monopolies are violently enforced, I choose GPLv3 for the software I really care for, because under the current circumstances this license is a tool that:
- Allows others to freely use, modify and distribute this software, without the risk of being sued;
- Enables me to pull all the valuable changes from public forks back to the trunk, also without the risk of being sued;
- Knocks down a peg individuals or companies willing to monopolize their use case or modifications of this software.