diff --git a/.gitignore b/.gitignore
index 0a0ff0f1..a1b09435 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,9 @@ build/
 bin/
 libs/
 
+target/
+*/target/
+
 *.iws
 *.iml
 *.ipr
diff --git a/build.gradle b/build.gradle
deleted file mode 100644
index 04b8a0af..00000000
--- a/build.gradle
+++ /dev/null
@@ -1,324 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <info@pgpainless.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-buildscript {
-
-    repositories {
-
-        maven {
-            url "https://plugins.gradle.org/m2/"
-        }
-        mavenLocal()
-        mavenCentral()
-    }
-    dependencies {
-        classpath "gradle.plugin.org.kt3k.gradle.plugin:coveralls-gradle-plugin:2.12.0"
-    }
-}
-
-plugins {
-    id 'org.jetbrains.kotlin.jvm' version "1.8.10"
-    id 'com.diffplug.spotless' version '6.22.0' apply false
-}
-
-apply from: 'version.gradle'
-
-allprojects {
-    apply plugin: 'java'
-    apply plugin: 'idea'
-    apply plugin: 'eclipse'
-    apply plugin: 'jacoco'
-    apply plugin: 'checkstyle'
-    apply plugin: 'kotlin'
-    apply plugin: 'com.diffplug.spotless'
-
-    java {
-        targetCompatibility = JavaVersion.VERSION_1_8
-    }
-
-    compileJava {
-        options.release = 8
-    }
-
-    // Only generate jar for submodules
-    // without this we would generate an empty pgpainless.jar for the project root
-    // https://stackoverflow.com/a/25445035
-    jar {
-        onlyIf { !sourceSets.main.allSource.files.isEmpty() }
-    }
-
-    // checkstyle
-    checkstyle {
-        toolVersion = '10.12.1'
-    }
-
-    spotless {
-      kotlin {
-        ktfmt().dropboxStyle()
-      }
-    }
-
-    group 'org.pgpainless'
-    description = "Simple to use OpenPGP API for Java based on Bouncycastle"
-    version = shortVersion
-
-    sourceCompatibility = javaSourceCompatibility
-
-    repositories {
-        mavenCentral()
-        mavenLocal()
-    }
-
-    // Reproducible Builds
-    tasks.withType(AbstractArchiveTask) {
-        preserveFileTimestamps = false
-        reproducibleFileOrder = true
-
-        dirMode = 0755
-        fileMode = 0644
-    }
-
-    // Compatibility of default implementations in kotlin interfaces with Java implementations.
-    tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
-        kotlinOptions {
-            freeCompilerArgs += ["-Xjvm-default=all-compatibility"]
-        }
-    }
-
-    project.ext {
-        rootConfigDir = new File(rootDir, 'config')
-        gitCommit = getGitCommit()
-        isContinuousIntegrationEnvironment = Boolean.parseBoolean(System.getenv('CI'))
-        isReleaseVersion = !isSnapshot
-        signingRequired = !(isSnapshot || isContinuousIntegrationEnvironment)
-        sonatypeCredentialsAvailable = project.hasProperty('sonatypeUsername') && project.hasProperty('sonatypePassword')
-        sonatypeSnapshotUrl = 'https://oss.sonatype.org/content/repositories/snapshots'
-        sonatypeStagingUrl = 'https://oss.sonatype.org/service/local/staging/deploy/maven2'
-    }
-
-    if (isSnapshot) {
-        version = version + '-SNAPSHOT'
-    }
-    def projectDirFile = new File("$projectDir")
-    if (!project.ext.isSnapshot && !'git describe --exact-match HEAD'.execute(null, projectDirFile).text.trim().equals(ext.shortVersion)) {
-        throw new InvalidUserDataException('Untagged version detected! Please tag every release.')
-    }
-    if (!version.endsWith('-SNAPSHOT') && version != 'git tag --points-at HEAD'.execute(null, projectDirFile).text.trim()) {
-        throw new InvalidUserDataException(
-                'Tag mismatch detected, version is ' + version + ' but should be ' +
-                        'git tag --points-at HEAD'.execute(null, projectDirFile).text.trim())
-    }
-
-    jacoco {
-        toolVersion = "0.8.8"
-    }
-
-    jacocoTestReport {
-        dependsOn test
-        sourceDirectories.setFrom(project.files(sourceSets.main.allSource.srcDirs))
-        classDirectories.setFrom(project.files(sourceSets.main.output))
-        reports {
-            xml.enabled true
-        }
-    }
-
-    test {
-        useJUnitPlatform()
-        testLogging {
-            events "passed", "skipped", "failed"
-            exceptionFormat "full"
-        }
-    }
-}
-
-subprojects {
-    apply plugin: 'maven-publish'
-    apply plugin: 'signing'
-
-    task sourcesJar(type: Jar, dependsOn: classes) {
-        classifier = 'sources'
-        from sourceSets.main.allSource
-    }
-    task javadocJar(type: Jar, dependsOn: javadoc) {
-        classifier = 'javadoc'
-        from javadoc.destinationDir
-    }
-    task testsJar(type: Jar, dependsOn: testClasses) {
-        classifier = 'tests'
-        from sourceSets.test.output
-    }
-
-    publishing {
-        publications {
-            mavenJava(MavenPublication) {
-                from components.java
-                artifact sourcesJar
-                artifact javadocJar
-                artifact testsJar
-                pom {
-                    name = 'PGPainless'
-                    description = 'Simple to use OpenPGP API for Java based on Bouncycastle'
-                    url = 'https://github.com/pgpainless/pgpainless'
-                    inceptionYear = '2018'
-
-                    scm {
-                        url = 'https://github.com/pgpainless/pgpainless'
-                        connection = 'scm:https://github.com/pgpainless/pgpainless'
-                        developerConnection = 'scm:git://github.com/pgpainless/pgpainless.git'
-                    }
-
-                    licenses {
-                        license {
-                            name = 'The Apache Software License, Version 2.0'
-                            url = 'http://www.apache.org/licenses/LICENSE-2.0.txt'
-                            distribution = 'repo'
-                        }
-                    }
-
-                    developers {
-                        developer {
-                            id = 'vanitasvitae'
-                            name = 'Paul Schaub'
-                            email = 'vanitasvitae@fsfe.org'
-                        }
-                    }
-                }
-            }
-        }
-        repositories {
-            if (sonatypeCredentialsAvailable) {
-                maven {
-                    url isSnapshot ? sonatypeSnapshotUrl : sonatypeStagingUrl
-                    credentials {
-                        username = sonatypeUsername
-                        password = sonatypePassword
-                    }
-                }
-            }
-        }
-    }
-
-    signing {
-        useGpgCmd()
-        required { signingRequired }
-        sign publishing.publications.mavenJava
-    }
-}
-
-def getGitCommit() {
-    def projectDirFile = new File("$projectDir")
-    def dotGit = new File("$projectDir/.git")
-    if (!dotGit.isDirectory()) return 'non-git build'
-
-    def cmd = 'git describe --always --tags --dirty=+'
-    def proc = cmd.execute(null, projectDirFile)
-    def gitCommit = proc.text.trim()
-    assert !gitCommit.isEmpty()
-
-    def srCmd = 'git symbolic-ref --short HEAD'
-    def srProc = srCmd.execute(null, projectDirFile)
-    srProc.waitForOrKill(10 * 1000)
-    if (srProc.exitValue() == 0) {
-        // Only add the information if the git command was
-        // successful. There may be no symbolic reference for HEAD if
-        // e.g. in detached mode.
-        def symbolicReference = srProc.text.trim()
-        assert !symbolicReference.isEmpty()
-        gitCommit += "-$symbolicReference"
-    }
-
-    gitCommit
-}
-
-apply plugin: "com.github.kt3k.coveralls"
-coveralls {
-	sourceDirs = files(subprojects.sourceSets.main.allSource.srcDirs).files.absolutePath
-}
-
-task jacocoRootReport(type: JacocoReport) {
-    dependsOn = subprojects.jacocoTestReport
-    sourceDirectories.setFrom(files(subprojects.sourceSets.main.allSource.srcDirs))
-    classDirectories.setFrom(files(subprojects.sourceSets.main.output))
-    executionData.setFrom(files(subprojects.jacocoTestReport.executionData))
-    reports {
-        xml.enabled true
-        xml.destination file("${buildDir}/reports/jacoco/test/jacocoTestReport.xml")
-    }
-    // We could remove the following setOnlyIf line, but then
-    // jacocoRootReport would silently be SKIPPED if something with
-    // the projectsWithUnitTests is wrong (e.g. a project is missing
-    // in there).
-    setOnlyIf { true }
-}
-
-task javadocAll(type: Javadoc) {
-    def currentJavaVersion = JavaVersion.current()
-    if (currentJavaVersion.compareTo(JavaVersion.VERSION_1_9) >= 0) {
-        options.addStringOption("-release", "8");
-    }
-    source subprojects.collect {project ->
-        project.sourceSets.main.allJava }
-    destinationDir = new File(buildDir, 'javadoc')
-    // Might need a classpath
-    classpath = files(subprojects.collect {project ->
-        project.sourceSets.main.compileClasspath})
-    options.linkSource = true
-    options.use = true
-    options.links = [
-            "https://docs.oracle.com/javase/${sourceCompatibility.getMajorVersion()}/docs/api/",
-    ] as String[]
-}
-
-if (JavaVersion.current().isJava8Compatible()) {
-    tasks.withType(Javadoc) {
-        // The '-quiet' as second argument is actually a hack,
-        // since the one paramater addStringOption doesn't seem to
-        // work, we extra add '-quiet', which is added anyway by
-        // gradle. See https://github.com/gradle/gradle/issues/2354
-        // See JDK-8200363 (https://bugs.openjdk.java.net/browse/JDK-8200363)
-        // for information about the -Xwerror option.
-        options.addStringOption('Xwerror', '-quiet')
-    }
-}
-
-/**
- * Fetch sha256 checksums of artifacts published to maven central.
- *
- * Example: gradle -Prelease=1.3.13 mavenCentralChecksums
- */
-task mavenCentralChecksums() {
-    description 'Fetch and display checksums for artifacts published to Maven Central'
-    String ver = project.hasProperty('release') ? release : shortVersion
-    doLast {
-        Process p = "curl -f https://repo1.maven.org/maven2/org/pgpainless/pgpainless-core/${ver}/pgpainless-core-${ver}.jar.sha256".execute()
-        if (p.waitFor() == 0) {
-            print p.text.trim()
-            println "  pgpainless-core/build/libs/pgpainless-core-${ver}.jar"
-        }
-
-        p = "curl -f https://repo1.maven.org/maven2/org/pgpainless/pgpainless-sop/${ver}/pgpainless-sop-${ver}.jar.sha256".execute()
-        if (p.waitFor() == 0) {
-            print p.text.trim()
-            println "  pgpainless-sop/build/libs/pgpainless-sop-${ver}.jar"
-        }
-
-        p = "curl -f https://repo1.maven.org/maven2/org/pgpainless/pgpainless-cli/${ver}/pgpainless-cli-${ver}-all.jar.sha256".execute()
-        if (p.waitFor() == 0) {
-            print p.text.trim()
-            println "  pgpainless-cli/build/libs/pgpainless-cli-${ver}-all.jar"
-        }
-
-        p = "curl -f https://repo1.maven.org/maven2/org/pgpainless/pgpainless-cli/${ver}/pgpainless-cli-${ver}.jar.sha256".execute()
-        if (p.waitFor() == 0) {
-            print p.text.trim()
-            println "  pgpainless-cli/build/libs/pgpainless-cli-${ver}.jar"
-        }
-
-        p = "curl -f https://repo1.maven.org/maven2/org/pgpainless/hsregex/${ver}/hsregex-${ver}.jar.sha256".execute()
-        if (p.waitFor() == 0) {
-            print p.text.trim()
-            println "  hsregex/build/libs/hsregex-${ver}.jar"
-        }
-    }
-}
diff --git a/pgpainless-cli/build.gradle b/pgpainless-cli/build.gradle
deleted file mode 100644
index d6550139..00000000
--- a/pgpainless-cli/build.gradle
+++ /dev/null
@@ -1,60 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-plugins {
-    id 'application'
-    id "com.github.johnrengelman.shadow" version "6.1.0"
-}
-
-dependencies {
-
-    testImplementation(project(":pgpainless-core"))
-
-    testImplementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
-
-    // implementation "ch.qos.logback:logback-core:1.2.6"
-    // We want logback logging in tests and in the app
-    testImplementation "ch.qos.logback:logback-classic:$logbackVersion"
-    implementation "ch.qos.logback:logback-classic:$logbackVersion"
-
-    implementation(project(":pgpainless-sop"))
-    implementation "org.pgpainless:sop-java-picocli:$sopJavaVersion"
-
-    // https://mvnrepository.com/artifact/com.google.code.findbugs/jsr305
-    implementation group: 'com.google.code.findbugs', name: 'jsr305', version: '3.0.2'
-}
-
-mainClassName = 'org.pgpainless.cli.PGPainlessCLI'
-
-application {
-    mainClass = mainClassName
-}
-/**
-jar {
-    duplicatesStrategy(DuplicatesStrategy.EXCLUDE)
-    manifest {
-        attributes 'Main-Class': "$mainClassName"
-    }
-
-    from {
-        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
-    } {
-        exclude "META-INF/*.SF"
-        exclude "META-INF/*.DSA"
-        exclude "META-INF/*.RSA"
-    }
-}
- */
-
-run {
-    // https://stackoverflow.com/questions/59445306/pipe-into-gradle-run
-    standardInput = System.in
-    // https://discuss.gradle.org/t/how-can-i-provide-command-line-args-to-application-started-with-gradle-run/6474/5
-    if (project.hasProperty("appArgs")) {
-        args Eval.me(appArgs)
-    }
-}
-
-// tasks."jar".dependsOn(":pgpainless-core:assemble", ":pgpainless-sop:assemble")
diff --git a/pgpainless-cli/pom.xml b/pgpainless-cli/pom.xml
new file mode 100644
index 00000000..ad5c7511
--- /dev/null
+++ b/pgpainless-cli/pom.xml
@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.pgpainless</groupId>
+        <artifactId>pgpainless-parent</artifactId>
+        <version>1.7.3-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>pgpainless-cli</artifactId>
+
+    <properties>
+        <mainClass>org.pgpainless.cli.PGPainlessCLI</mainClass>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>pgpainless-sop</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>sop-java-picocli</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- Assembly -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>${maven.assembly.plugin.version}</version>
+                <configuration>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                    <archive>
+                        <manifest>
+                            <mainClass>${mainClass}</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+
+        </plugins>
+    </build>
+</project>
\ No newline at end of file
diff --git a/pgpainless-core/build.gradle b/pgpainless-core/build.gradle
deleted file mode 100644
index bab6ecf1..00000000
--- a/pgpainless-core/build.gradle
+++ /dev/null
@@ -1,36 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-plugins {
-    id 'java-library'
-}
-
-dependencies {
-    // JUnit
-    testImplementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
-    testImplementation "org.junit.jupiter:junit-jupiter-params:$junitVersion"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
-
-    // Mocking Components
-    testImplementation "org.mockito:mockito-core:$mockitoVersion"
-
-    // Logging
-    api "org.slf4j:slf4j-api:$slf4jVersion"
-    testImplementation "ch.qos.logback:logback-classic:$logbackVersion"
-
-    // Bouncy Castle
-    api "org.bouncycastle:bcprov-jdk18on:$bouncyCastleVersion"
-    api "org.bouncycastle:bcpg-jdk18on:$bouncyPgVersion"
-    // api(files("../libs/bcpg-jdk18on-1.70.jar"))
-
-    // @Nullable, @Nonnull annotations
-    implementation "com.google.code.findbugs:jsr305:3.0.2"
-}
-
-// https://docs.gradle.org/current/userguide/java_library_plugin.html#sec:java_library_modular_auto
-tasks.named('jar') {
-    manifest {
-        attributes('Automatic-Module-Name': 'org.pgpainless.core')
-    }
-}
diff --git a/pgpainless-core/pom.xml b/pgpainless-core/pom.xml
new file mode 100644
index 00000000..4d346d03
--- /dev/null
+++ b/pgpainless-core/pom.xml
@@ -0,0 +1,112 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.pgpainless</groupId>
+        <artifactId>pgpainless-parent</artifactId>
+        <version>1.7.3-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>pgpainless-core</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>sop-java</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcprov-jdk18on</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcpg-jdk18on</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcutil-jdk18on</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+            <scope>compile</scope>
+        </dependency>
+
+        <!-- JUnit -->
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test-junit5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- Mockito -->
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testng</groupId>
+            <artifactId>testng</artifactId>
+            <version>7.10.2</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- Kotlin Compile -->
+            <plugin>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <groupId>org.jetbrains.kotlin</groupId>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
\ No newline at end of file
diff --git a/pgpainless-sop/build.gradle b/pgpainless-sop/build.gradle
deleted file mode 100644
index aa0f5993..00000000
--- a/pgpainless-sop/build.gradle
+++ /dev/null
@@ -1,49 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-import org.apache.tools.ant.filters.*
-plugins {
-    id 'java-library'
-}
-
-group 'org.pgpainless'
-
-repositories {
-    mavenCentral()
-    mavenLocal()
-}
-
-dependencies {
-    testImplementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
-    testImplementation "org.junit.jupiter:junit-jupiter-params:$junitVersion"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
-
-    // Logging
-    testImplementation "ch.qos.logback:logback-classic:$logbackVersion"
-
-    // Depend on "shared" sop-java test suite (fixtures are turned into tests by inheritance inside test sources)
-    testImplementation(testFixtures("org.pgpainless:sop-java:$sopJavaVersion"))
-
-    implementation(project(":pgpainless-core"))
-    api "org.pgpainless:sop-java:$sopJavaVersion"
-
-    implementation "com.google.code.findbugs:jsr305:3.0.2"
-}
-
-processResources {
-    filter ReplaceTokens, tokens: [
-            "project.version": project.version.toString()
-    ]
-}
-
-test {
-    useJUnitPlatform()
-    environment("test.implementation", "sop.testsuite.pgpainless.PGPainlessSopInstanceFactory")
-}
-
-// https://docs.gradle.org/current/userguide/java_library_plugin.html#sec:java_library_modular_auto
-tasks.named('jar') {
-    manifest {
-        attributes('Automatic-Module-Name': 'org.pgpainless.sop')
-    }
-}
diff --git a/pgpainless-sop/pom.xml b/pgpainless-sop/pom.xml
new file mode 100644
index 00000000..8e21eb3d
--- /dev/null
+++ b/pgpainless-sop/pom.xml
@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.pgpainless</groupId>
+        <artifactId>pgpainless-parent</artifactId>
+        <version>1.7.3-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>pgpainless-sop</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>sop-java</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>sop-java-testfixtures</artifactId>
+            <version>10.0.3-SNAPSHOT</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.pgpainless</groupId>
+            <artifactId>pgpainless-core</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.2.2</version>
+                <configuration>
+                    <environmentVariables>
+                        <test.implementation>sop.testsuite.pgpainless.PGPainlessSopInstanceFactory</test.implementation>
+                    </environmentVariables>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>
\ No newline at end of file
diff --git a/pgpainless-sop/src/main/resources/pgpainless-sop.properties b/pgpainless-sop/src/main/resources/pgpainless-sop.properties
index d71e996b..c663fa18 100644
--- a/pgpainless-sop/src/main/resources/pgpainless-sop.properties
+++ b/pgpainless-sop/src/main/resources/pgpainless-sop.properties
@@ -1 +1 @@
-pgpainless-sop-version=@project.version@
\ No newline at end of file
+pgpainless-sop-version=${project.version}
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 00000000..745ab315
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,251 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.pgpainless</groupId>
+    <artifactId>pgpainless-parent</artifactId>
+    <version>1.7.3-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>pgpainless-core</module>
+        <module>pgpainless-sop</module>
+        <module>pgpainless-cli</module>
+    </modules>
+
+    <name>PGPainless</name>
+    <description>Simple to use OpenPGP API for Java based on Bouncycastle</description>
+    <url>https://github.com/pgpainless/pgpainless</url>
+    <inceptionYear>2018</inceptionYear>
+    <licenses>
+        <license>
+            <name>The Apache Software License, Version 2.0</name>
+            <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+    <developers>
+        <developer>
+            <id>vanitasvitae</id>
+            <name>Paul Schaub</name>
+            <email>vanitasvitae@fsfe.org</email>
+        </developer>
+    </developers>
+    <scm>
+        <connection>scm:https://github.com/pgpainless/pgpainless</connection>
+        <developerConnection>scm:git://github.com/pgpainless/pgpainless.git</developerConnection>
+        <url>https://github.com/pgpainless/pgpainless</url>
+    </scm>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <kotlin.version>1.8.10</kotlin.version>
+
+        <maven.compiler.source>${java.version}</maven.compiler.source>
+        <maven.compiler.target>${java.version}</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.assembly.plugin.version>3.3.0</maven.assembly.plugin.version>
+        <bouncycastle.version>1.78.1</bouncycastle.version>
+        <sop-java.version>10.0.3</sop-java.version>
+        <slf4j.version>1.7.36</slf4j.version>
+        <junit.version>5.8.2</junit.version>
+        <mockito.version>4.5.1</mockito.version>
+
+        <project.build.outputTimestamp>2023-01-01T00:00:00Z</project.build.outputTimestamp>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <!-- Kotlin -->
+            <dependency>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-stdlib</artifactId>
+                <version>${kotlin.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-test-junit5</artifactId>
+                <version>${kotlin.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-reflect</artifactId>
+                <version>${kotlin.version}</version>
+            </dependency>
+
+            <!-- Bouncy Castle -->
+            <dependency>
+                <groupId>org.bouncycastle</groupId>
+                <artifactId>bcprov-jdk18on</artifactId>
+                <version>${bouncycastle.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.bouncycastle</groupId>
+                <artifactId>bcpg-jdk18on</artifactId>
+                <version>${bouncycastle.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.bouncycastle</groupId>
+                <artifactId>bcutil-jdk18on</artifactId>
+                <version>${bouncycastle.version}</version>
+            </dependency>
+
+            <!-- SOP-Java -->
+            <dependency>
+                <groupId>org.pgpainless</groupId>
+                <artifactId>sop-java</artifactId>
+                <version>${sop-java.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.pgpainless</groupId>
+                <artifactId>sop-java-testfixtures</artifactId>
+                <version>${sop-java.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.pgpainless</groupId>
+                <artifactId>sop-java-picocli</artifactId>
+                <version>${sop-java.version}</version>
+            </dependency>
+
+            <!-- SLF4J -->
+            <dependency>
+                <groupId>org.slf4j</groupId>
+                <artifactId>slf4j-api</artifactId>
+                <version>${slf4j.version}</version>
+            </dependency>
+
+            <!-- @Nullable, @Nonnull -->
+            <dependency>
+                <groupId>com.google.code.findbugs</groupId>
+                <artifactId>jsr305</artifactId>
+                <version>3.0.2</version>
+            </dependency>
+
+            <!-- Test -->
+            <!-- JUnit -->
+            <dependency>
+                <groupId>org.junit.jupiter</groupId>
+                <artifactId>junit-jupiter-engine</artifactId>
+                <version>${junit.version}</version>
+                <scope>test</scope>
+            </dependency>
+            <dependency>
+                <groupId>org.junit.jupiter</groupId>
+                <artifactId>junit-jupiter-params</artifactId>
+                <version>${junit.version}</version>
+                <scope>test</scope>
+            </dependency>
+            <dependency>
+                <groupId>org.junit.jupiter</groupId>
+                <artifactId>junit-jupiter-api</artifactId>
+                <version>${junit.version}</version>
+                <scope>test</scope>
+            </dependency>
+
+            <!-- Mockito -->
+            <dependency>
+                <groupId>org.mockito</groupId>
+                <artifactId>mockito-core</artifactId>
+                <version>${mockito.version}</version>
+                <scope>test</scope>
+            </dependency>
+
+            <!-- Logback -->
+            <dependency>
+                <groupId>ch.qos.logback</groupId>
+                <artifactId>logback-classic</artifactId>
+                <version>1.5.0</version>
+                <scope>test</scope>
+            </dependency>
+
+        </dependencies>
+    </dependencyManagement>
+
+    <build>
+        <!-- Plugins -->
+        <plugins>
+        </plugins>
+
+        <!-- Shared plugin configuration -->
+        <pluginManagement>
+            <plugins>
+
+                <plugin>
+                    <groupId>org.jetbrains.kotlin</groupId>
+                    <artifactId>kotlin-maven-plugin</artifactId>
+                    <version>${kotlin.version}</version>
+                    <executions>
+                        <execution>
+                            <id>compile</id>
+                            <phase>process-sources</phase>
+                            <goals>
+                                <goal>compile</goal>
+                            </goals>
+                            <configuration>
+                                <sourceDirs>
+                                    <source>src/main/java</source>
+                                    <source>src/main/kotlin</source>
+                                </sourceDirs>
+                            </configuration>
+                        </execution>
+                        <execution>
+                            <id>test-compile</id>
+                            <phase>process-test-sources</phase>
+                            <goals>
+                                <goal>test-compile</goal>
+                            </goals>
+                            <configuration>
+                                <sourceDirs>
+                                    <source>src/test/java</source>
+                                    <source>src/test/kotlin</source>
+                                    <source>src/test/resources</source>
+                                </sourceDirs>
+                            </configuration>
+                        </execution>
+                    </executions>
+                    <configuration>
+                        <jvmTarget>${java.version}</jvmTarget>
+                        <args>
+                            <arg>-Xjvm-default=all-compatibility</arg>
+                        </args>
+                    </configuration>
+                </plugin>
+
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <executions>
+                        <execution>
+                            <id>default-compile</id>
+                            <phase>none</phase>
+                        </execution>
+                        <execution>
+                            <id>default-testCompile</id>
+                            <phase>none</phase>
+                        </execution>
+                        <execution>
+                            <id>compile</id>
+                            <phase>compile</phase>
+                            <goals>
+                                <goal>compile</goal>
+                            </goals>
+                        </execution>
+                        <execution>
+                            <id>testCompile</id>
+                            <phase>test-compile</phase>
+                            <goals>
+                                <goal>testCompile</goal>
+                            </goals>
+                        </execution>
+                    </executions>
+                    <configuration>
+                        <source>${java.version}</source>
+                        <target>${java.version}</target>
+                    </configuration>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+</project>
diff --git a/settings.gradle b/settings.gradle
deleted file mode 100644
index aea19392..00000000
--- a/settings.gradle
+++ /dev/null
@@ -1,10 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <info@pgpainless.org>
-//
-// SPDX-License-Identifier: CC0-1.0
-
-rootProject.name = 'PGPainless'
-
-include 'pgpainless-core',
-        'pgpainless-sop',
-        'pgpainless-cli'
-
diff --git a/version.gradle b/version.gradle
deleted file mode 100644
index 07c66ec5..00000000
--- a/version.gradle
+++ /dev/null
@@ -1,19 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <info@pgpainless.org>
-//
-// SPDX-License-Identifier: CC0-1.0
-
-allprojects {
-    ext {
-        shortVersion = '1.7.3'
-        isSnapshot = true
-        pgpainlessMinAndroidSdk = 10
-        javaSourceCompatibility = 1.8
-        bouncyCastleVersion = '1.78.1'
-        bouncyPgVersion = bouncyCastleVersion
-        junitVersion = '5.8.2'
-        logbackVersion = '1.5.13'
-        mockitoVersion = '4.5.1'
-        slf4jVersion = '1.7.36'
-        sopJavaVersion = '10.0.3'
-    }
-}