#1150 - Add Argon2 support

- Add argon2 implementation

- Extract argon2 library check to method on Argon 2
- Add link to Wiki page on errors
- Check within Argon2Test if the test cases should be run, not in the abstract parent

src/main/java/fr/xephi/authme/security/HashAlgorithm.java

@@ -7,6 +7,7 @@ import fr.xephi.authme.security.crypts.EncryptionMethod;
  */
 public enum HashAlgorithm {
 
+    ARGON2(fr.xephi.authme.security.crypts.Argon2.class),
     BCRYPT(fr.xephi.authme.security.crypts.BCrypt.class),
     BCRYPT2Y(fr.xephi.authme.security.crypts.BCrypt2y.class),
     CRAZYCRYPT1(fr.xephi.authme.security.crypts.CrazyCrypt1.class),

src/main/java/fr/xephi/authme/security/crypts/Argon2.java

@@ -0,0 +1,48 @@
+package fr.xephi.authme.security.crypts;
+
+import de.mkammerer.argon2.Argon2Constants;
+import de.mkammerer.argon2.Argon2Factory;
+import fr.xephi.authme.ConsoleLogger;
+import fr.xephi.authme.security.crypts.description.HasSalt;
+import fr.xephi.authme.security.crypts.description.Recommendation;
+import fr.xephi.authme.security.crypts.description.SaltType;
+import fr.xephi.authme.security.crypts.description.Usage;
+
+@Recommendation(Usage.RECOMMENDED)
+@HasSalt(value = SaltType.TEXT, length = Argon2Constants.DEFAULT_SALT_LENGTH)
+// Note: Argon2 is actually a salted algorithm but salt generation is handled internally
+// and isn't exposed to the outside, so we treat it as an unsalted implementation
+public class Argon2 extends UnsaltedMethod {
+
+    private de.mkammerer.argon2.Argon2 argon2;
+
+    public Argon2() {
+        argon2 = Argon2Factory.create();
+    }
+
+    /**
+     * Checks if the argon2 library is available in java.library.path.
+     *
+     * @return true if the library is present, false otherwise
+     */
+    public static boolean isLibraryLoaded() {
+        try {
+            System.loadLibrary("argon2");
+            return true;
+        } catch (UnsatisfiedLinkError e) {
+            ConsoleLogger.logException(
+                "Cannot find argon2 library: https://github.com/AuthMe/AuthMeReloaded/wiki/Argon2-as-Password-Hash", e);
+        }
+        return false;
+    }
+
+    @Override
+    public String computeHash(String password) {
+        return argon2.hash(2, 65536, 1, password);
+    }
+
+    @Override
+    public boolean comparePassword(String password, HashedPassword hashedPassword, String name) {
+        return argon2.verify(hashedPassword.getHash(), password);
+    }
+}