init project. AES_GCM, placeholders

.gitignore

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+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+.kotlin
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

.idea/.gitignore

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+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" default="true" project-jdk-name="openjdk-26" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>

.idea/modules.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/XACrypto.iml" filepath="$PROJECT_DIR$/XACrypto.iml" />
+    </modules>
+  </component>
+</project>

.idea/vcs.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

XACrypto.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

src/main/java/de/caydenno1/xacrypto/XACrypto.java

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+package main.java.de.caydenno1.xacrypto;
+
+public class XACrypto {
+    private XACrypto() {}
+}

src/main/java/de/caydenno1/xacrypto/encryption/AES_GCM.java

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+package main.java.de.caydenno1.xacrypto.encryption;
+
+import javax.crypto.Cipher;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+public class AES_GCM {
+    private static final String AES = "AES";
+    private static final String AES_GCM = "AES/GCM/NoPadding";
+
+    private AES_GCM() {}
+
+    public static SecretKey genKey(int bits) throws Exception {
+        KeyGenerator g = KeyGenerator.getInstance(AES);
+        g.init(bits);
+
+        return g.generateKey();
+    }
+
+    public static String encrypt(String pln, SecretKey k, int TAG, int IV) throws Exception {
+        byte[] iv = new byte[IV];
+        new SecureRandom().nextBytes(iv);
+
+        Cipher c  = Cipher.getInstance(AES_GCM);
+        c.init(Cipher.ENCRYPT_MODE, k, new GCMParameterSpec(TAG, iv));
+
+        byte[] citext = c.doFinal(pln.getBytes());
+
+        byte[] comb = new byte[iv.length + citext.length];
+        System.arraycopy(iv, 0, comb, 0, iv.length);
+        System.arraycopy(citext, 0, comb, iv.length, citext.length);
+
+        return Base64.getEncoder().encodeToString(comb);
+    }
+
+    public static String decrypt(String enc, SecretKey k, int TAG, int IV) throws Exception {
+        byte[] dat = Base64.getDecoder().decode(enc);
+
+        byte[] iv = new byte[IV];
+        byte[] cit = new byte[dat.length - IV];
+
+        System.arraycopy(dat, 0, iv, 0, IV);
+        System.arraycopy(dat, IV, cit, 0, cit.length);
+
+        Cipher ci = Cipher.getInstance(AES_GCM);
+        ci.init(Cipher.DECRYPT_MODE, k, new GCMParameterSpec(TAG, iv));
+        return new String(ci.doFinal(cit));
+    }
+}