How to get android signing certificate back from jenkins plugin

First, identify correct Jenkins home directory. Go to "Manage Jenkins" and then "System Information". Find a value of JENKINS_HOME.

Next, log in to Jenkins via SSH and go to that directory. A file named credentials.xml will contain your secrets.

Find the ID of you certificate (e.g. in the URL):

Finally, fire up a scripting console of your Jenkins instance (available at /script URL or via "Manage Jenkins" -> "Script Console") and execute this script:

import com.cloudbees.plugins.credentials.*import hudson.security.*import java.security.*import javax.xml.bind.DatatypeConverterdef creds =  CredentialsMatchers                .firstOrNull(                        CredentialsProvider                            .lookupCredentials(                                Credentials.class,                                Jenkins.getActiveInstance(),                                ACL.SYSTEM,                                Collections.emptyList()                            ),                        CredentialsMatchers.withId("9X9X99XX-XX9X-9X99-9X9X-9X9X9999XXX9")                )// This will print a decrypted passworddef password = creds.passwordprintln password// This will print all the available aliasescreds.keyStore.aliases().each { println it }// Imagine, the alias you need is myapp.// Get JVM representation of you certificate and keydef cert = creds.keyStore.getEntry("myapp", new KeyStore.PasswordProtection(password.toCharArray())).certificatedef privKey = creds.keyStore.getEntry("myapp", new KeyStore.PasswordProtection(password.toCharArray())).privateKey// Format certificate and keycertpem = "-----BEGIN CERTIFICATE-----\n" +        DatatypeConverter.printBase64Binary(cert.encoded) +        "\n-----END CERTIFICATE-----\n";keypem  = "-----BEGIN RSA PRIVATE KEY-----\n" +        DatatypeConverter.printBase64Binary(privKey.encoded) +        "\n-----END RSA PRIVATE KEY-----\n";// Print themprintln certpemprintln keypem

BTW, you can find your encoded credentials by ID in credentials.xml in Jenins home. It should look like:

<com.cloudbees.plugins.credentials.impl.CertificateCredentialsImpl>    <scope>GLOBAL</scope>    <id>9X9X99XX-XX9X-9X99-9X9X-9X9X9999XXX9</id>    <description>App signing certificate</description>    <keyStoreSource class="com.cloudbees.plugins.credentials.impl.CertificateCredentialsImpl$UploadedKeyStoreSource">        <uploadedKeystoreBytes>{ENCRYPTED_CERTIFICATE}</uploadedKeystoreBytes>    </keyStoreSource>    <password>{ENCRYPTED_PASSWORD}</password></com.cloudbees.plugins.credentials.impl.CertificateCredentialsImpl>