[//]: # (title: Plugin Signing) Plugin Signing is a mechanism introduced in the 2021.2 release cycle to increase security in [JetBrains Marketplace](https://plugins.jetbrains.com) and all of our IntelliJ-based IDEs. The Marketplace signing is designed to ensure that plugins are not modified over the course of the publishing and delivery pipeline. If the plugin is not signed by the author or if a certificate has been revoked, a warning dialog will appear in the IDE during installation. On our side, we will check if the public part of a key is present, and we will verify the signature. This is similar to the [Google upload key](https://developer.android.com/studio/publish/app-signing#generate-key) mechanism. ## How Signing Works To be sure a file has not been modified, the file will be signed twice – first by the plugin author, then by JetBrains Marketplace. The plugin author's sign-verify process is as follows: - A plugin author generates a key pair and uploads the public part to [JetBrains Hub](https://www.jetbrains.com/hub/). - A build tool signs a plugin file during the assembly process. - The user uploads the plugin file to JetBrains Marketplace. - JetBrains Marketplace checks if the public key is present in the [JetBrains Hub](https://www.jetbrains.com/hub/) user profile. - JetBrains Marketplace verifies the signature. - The JetBrains sign-verify process is as follows: JetBrains CA is used as the source of truth here. Its public part will be added to the IDE Java TrustStore, while the private part will be used only once to generate an intermediate certificate. The private key of JetBrains CA is super-secret; in fact, we've already said too much. - The intermediate certificate issues a certificate that will be used to sign plugins. This way, it will be possible to re-generate this certificate without access to JetBrains CA's super-secret private key. The private key of the intermediate certificate is issued and kept in the AWS Certificate Manager, and no application has access to it; people's access is also limited. So now we have an AWS-based Intermediate CA. The public part of the intermediate certificate will be added to the plugin file together with the signing certificate. - The certificate used to sign plugins is stored securely, too. JetBrains Marketplace uses AWS KMS as a signature provider to sign plugin files. ## Signing Methods To provide a suitable method for plugin signing, we have introduced the [Marketplace ZIP Signer](https://github.com/JetBrains/marketplace-zip-signer) library. It can be executed using the `signPlugin` task provided by the [Gradle IntelliJ Plugin](https://github.com/JetBrains/gradle-intellij-plugin) if your project is Gradle-based. Alternatively, it can be used standalone [CLI Tool](#cli-tool). Both methods require a private certificate key to be already present. ### Generate Private Key To generate an RSA `private.pem` private key, run the `openssl genpkey` command in the terminal, as below: ```bash openssl genpkey -aes-256-cbc -algorithm RSA -out private.pem -pkeyopt rsa_keygen_bits:4096 ``` At this point, the content of the generated `private.key` should be provided to the `signPlugin.privateKey` property. Provided password should be specified as `signPlugin.password` property in the `signPlugin` configuration. As a next step, we'll generate a `chain.crt` certificate chain with: ```bash openssl req -key private.key -new -x509 -days 365 -out chain.crt ``` The content of the `chain.crt` file will be used for the `signPlugin.certificateChain` property. ### Gradle IntelliJ Plugin The Gradle IntelliJ Plugin in version `1.x` provides the `signPlugin` task which will be executed automatically right before the `publishPlugin` task when `signPlugin.certificateChain` and `signPlugin.privateKey` signing properties are specified. Otherwise, it'll be skipped. An example `pluginSigning` configuration may look like: ```Groovy signPlugin { certificateChain = """ -----BEGIN CERTIFICATE----- MIIElgCCAn4CCQDo83LWYj2QSTANBgkqhkiG9w0BAQsFADANMQswCQYDVQQGEwJQ ... gdZzxCN8t1EmH8kD2Yve6YKGFCRAIIzveEg= -----END CERTIFICATE----- """.stripIndent() privateKey = """ -----BEGIN RSA PRIVATE KEY----- MIIJKgIBAAKCAgEAwU8awS22Rw902BmwVDDBMlTREX440BAAVM40NW3E0lJ7YTJG ... EnNBfIVFhh6khisKqTBWSEo5iS2RYJcuZs961riCn1LARztiaXL4l17oW8t+Qw== -----END RSA PRIVATE KEY----- """.stripIndent() password = "8awS22%#3(4wVDDBMlTREX" } publishPlugin { token = "perm:a961riC....l17oW8t+Qw==" } ``` ```Kotlin signPlugin { certificateChain.set(""" -----BEGIN CERTIFICATE----- MIIElgCCAn4CCQDo83LWYj2QSTANBgkqhkiG9w0BAQsFADANMQswCQYDVQQGEwJQ ... gdZzxCN8t1EmH8kD2Yve6YKGFCRAIIzveEg= -----END CERTIFICATE----- """.trimIndent()) privateKey.set(""" -----BEGIN RSA PRIVATE KEY----- MIIJKgIBAAKCAgEAwU8awS22Rw902BmwVDDBMlTREX440BAAVM40NW3E0lJ7YTJG ... EnNBfIVFhh6khisKqTBWSEo5iS2RYJcuZs961riCn1LARztiaXL4l17oW8t+Qw== -----END RSA PRIVATE KEY----- """.trimIndent()) password.set("8awS22%#3(4wVDDBMlTREX") } publishPlugin { token.set("perm:a961riC....l17oW8t+Qw==") } ``` > Do not commit your credentials to the Version Control System! To avoid that, you may use environment variables, like: > ``` > token.set(System.getenv("PUBLISH_TOKEN")) > ``` > {type="warning"} ### Provide Secrets to IDE To avoid storing hardcoded values in the project configuration, the most suitable method for local development would be using environment variables provided within the _Run/Debug Configuration_. To specify secrets like `PUBLISH_TOKEN` and values required for the `signPlugin` task, modify your Gradle configuration as follows: ```Groovy signPlugin { certificateChain = System.getenv("CERTIFICATE_CHAIN") privateKey = System.getenv("PRIVATE_KEY") password = System.getenv("PRIVATE_KEY_PASSWORD") } publishPlugin { token = System.getenv("PUBLISH_TOKEN") } ``` ```Kotlin signPlugin { certificateChain.set(System.getenv("CERTIFICATE_CHAIN")) privateKey.set(System.getenv("PRIVATE_KEY")) password.set(System.getenv("PRIVATE_KEY_PASSWORD")) } publishPlugin { token.set(System.getenv("PUBLISH_TOKEN")) } ``` In the _Run/Debug Configuration_ for `publishPlugin` Gradle task, provide _Environment Variables_ using relevant environment variable names: ![Run/Debug Configuration Environment Variables](plugin_singing_env_variables.png) ### CLI Tool CLI tool is required in case you don't rely on the Gradle IntelliJ Plugin – i.e. when working with on Themes. To get the latest Marketplace ZIP Signer CLI Tool, visit the [JetBrains/marketplace-zip-signer](https://github.com/JetBrains/marketplace-zip-signer/releases) GitHub Releases page. After downloading the `zip-signer-cli.jar`, execute it as below: ```bash java -jar zip-signer-cli.jar sign\ -in "unsigned.zip"\ -out "signed.zip"\ -cert "/path/to/chain.crt"\ -key "/path/to/private.pem"\ -key-pass "PRIVATE_KEY_PASSWORD" ``` ## Signing for custom repositories Signing plugins hosted on a custom repository can be accomplished for added trust between the repository and installation, however unlike the marketplace, the custom repository will not re-sign the plugin with the Jetbrains key. Instead a trusted private CA or self-signed certificate can be used to sign and validate plugins. ### Verification Before looking at how we can sign a plugin, lets first revierw how verification works when a non-Jetbrains certificate is used. As of 2021.2, during verification, IntelliJ-based IDEs check if the plugin was signed by the Jetbrains CA certificate or any public keys provided by the user via `Preferences > Plugins > Manage Plugin Certificates`. In 2021.2.1, a system property has been added: `intellij.plugins.truststore` which can point to a trusted JKS truststore. During verification, the plugins public key is extracted from the signature and the last certificate entry in the chain matched against the certificates stored in one of the storages from above. ### Using a trusted internal CA If an internal CA is available, you can use this to generate certificates to be used for signing. Its important when choosing this route that the certificate chain includes the root CA public key at the end of the chain. With this approach, existing internal truststores may exist and could be used. Be sure when choosing a truststore that the CAs are limited to the internal CAs you trust. Using an truststore with public CAs can expose the users to an attack vector. If adding a truststore to a users environment is not possible, the user may also add the root CAs public key to `Preferences > Plugins > Manage Plugin Certificates` ### Using self-signed certificates Using a self-signed certificate is an option if no internal CAs exist. To generate the key and public key, see: [Generate Private Key](#Generate Private Key) If providing users with a truststore, you can generate one with the public key using keytool: ```bash keytool -import -alias IdeaPlugin -file chain.crt -keystore pluginKeystore.jks -storepass changeit ``` (note: the truststore password must remain `changeit`) Otherwise users may add the public key manually to `Preferences > Plugins > Manage Plugin Certificates`.