Introduce sop-java-json-gson module

settings.gradle

@@ -7,5 +7,6 @@ rootProject.name = 'SOP-Java'
 include 'sop-java',
         'sop-java-picocli',
         'sop-java-testfixtures',
-        'external-sop'
+        'external-sop',
+        'sop-java-json-gson'
 

sop-java-json-gson/README.md

@@ -0,0 +1,13 @@
+<!--
+SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+
+SPDX-License-Identifier: Apache-2.0
+-->
+
+# SOP-Java-JSON-GSON
+
+## JSON Parsing VERIFICATION extension JSON using Gson
+
+Since revision 11, the SOP specification defines VERIFICATIONS extension JSON.
+
+This module implements the `JSONParser` and `JSONSerializer` interfaces using Googles Gson library.

sop-java-json-gson/build.gradle

@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+plugins {
+    id 'java-library'
+}
+
+group 'org.pgpainless'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
+    implementation "org.junit.jupiter:junit-jupiter-params:$junitVersion"
+    runtimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
+
+    implementation project(":sop-java")
+    api "org.slf4j:slf4j-api:$slf4jVersion"
+    testImplementation "ch.qos.logback:logback-classic:$logbackVersion"
+
+    // @Nonnull, @Nullable...
+    implementation "com.google.code.findbugs:jsr305:$jsrVersion"
+
+    api "com.google.code.gson:gson:$gsonVersion"
+}

sop-java-json-gson/src/main/kotlin/sop/GsonParser.kt

@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop
+
+import com.google.gson.Gson
+import com.google.gson.JsonSyntaxException
+import com.google.gson.reflect.TypeToken
+import java.text.ParseException
+
+class GsonParser(
+    private val gson: Gson = Gson()
+) : Verification.JSONParser {
+
+    override fun parse(string: String): Verification.JSON {
+        try {
+            return gson.fromJson(string, object : TypeToken<Verification.JSON>(){}.type)
+        } catch (e: JsonSyntaxException) {
+            throw ParseException(e.message, 0)
+        }
+    }
+}

sop-java-json-gson/src/main/kotlin/sop/GsonSerializer.kt

@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop
+
+import com.google.gson.Gson
+
+class GsonSerializer(
+    private val gson: Gson = Gson()
+) : Verification.JSONSerializer {
+
+    override fun serialize(json: Verification.JSON): String {
+        return gson.toJson(json)
+    }
+}

sop-java-json-gson/src/test/kotlin/sop/GsonSerializerAndParserTest.kt

@@ -0,0 +1,96 @@
+// SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import java.text.ParseException
+
+class GsonSerializerAndParserTest {
+
+    private val serializer: GsonSerializer = GsonSerializer()
+    private val parser: GsonParser = GsonParser()
+
+    @Test
+    fun simpleSingleTest() {
+        val before = Verification.JSON("/tmp/alice.pgp")
+
+        val json = serializer.serialize(before)
+        assertEquals("{\"signers\":[\"/tmp/alice.pgp\"]}", json)
+
+        val after = parser.parse(json)
+
+        assertEquals(before, after)
+    }
+
+    @Test
+    fun simpleListTest() {
+        val before = Verification.JSON(listOf("/tmp/alice.pgp", "/tmp/bob.asc"))
+
+        val json = serializer.serialize(before)
+        assertEquals("{\"signers\":[\"/tmp/alice.pgp\",\"/tmp/bob.asc\"]}", json)
+
+        val after = parser.parse(json)
+
+        assertEquals(before, after)
+    }
+
+    @Test
+    fun withCommentTest() {
+        val before = Verification.JSON(
+            listOf("/tmp/alice.pgp"),
+            "This is a comment.",
+            null)
+
+        val json = serializer.serialize(before)
+        assertEquals("{\"signers\":[\"/tmp/alice.pgp\"],\"comment\":\"This is a comment.\"}", json)
+
+        val after = parser.parse(json)
+
+        assertEquals(before, after)
+    }
+
+    @Test
+    fun withExtStringTest() {
+        val before = Verification.JSON(
+            listOf("/tmp/alice.pgp"),
+            "This is a comment.",
+            "This is an ext object string.")
+
+        val json = serializer.serialize(before)
+        assertEquals("{\"signers\":[\"/tmp/alice.pgp\"],\"comment\":\"This is a comment.\",\"ext\":\"This is an ext object string.\"}", json)
+
+        val after = parser.parse(json)
+
+        assertEquals(before, after)
+    }
+
+    @Test
+    fun withExtListTest() {
+        val before = Verification.JSON(
+            listOf("/tmp/alice.pgp"),
+            "This is a comment.",
+            listOf(1.0,2.0,3.0))
+
+        val json = serializer.serialize(before)
+        assertEquals("{\"signers\":[\"/tmp/alice.pgp\"],\"comment\":\"This is a comment.\",\"ext\":[1.0,2.0,3.0]}", json)
+
+        val after = parser.parse(json)
+
+        assertEquals(before, after)
+    }
+
+    @Test
+    fun parseInvalidJSON() {
+        assertThrows<ParseException> { parser.parse("Invalid") }
+    }
+
+    @Test
+    fun parseMalformedJSON() {
+        // Missing '}'
+        assertThrows<ParseException> { parser.parse("{\"signers\":[\"Alice\"]") }
+    }
+}