Implement Argon2 password hashing and verification in user management

pom.xml

@@ -63,6 +63,12 @@
       <version>2.5</version>
       <scope>provided</scope>
     </dependency>
+    <!-- https://mvnrepository.com/artifact/de.mkammerer/argon2-jvm -->
+    <dependency>
+        <groupId>de.mkammerer</groupId>
+        <artifactId>argon2-jvm</artifactId>
+        <version>2.12</version>
+    </dependency>
   </dependencies>
 
   <build>

src/main/java/com/threerings/user/Crypto.java

@@ -0,0 +1,65 @@
+package com.threerings.user;
+
+import de.mkammerer.argon2.Argon2;
+import de.mkammerer.argon2.Argon2Factory;
+
+public class Crypto {
+
+    protected static final Argon2 argon2 = Argon2Factory.create();
+
+    private static final int HASH_ITERATIONS = 2;
+    private static final int MEMORY_COST_KB = 65536;
+    private static final int PARALLELISM = 1;
+
+    /**
+     * Hashes the given password using Argon2.
+     *
+     * @param password the password to hash
+     * @return the hashed password
+     */
+    public static String hashPassword(char[] password) {
+        return argon2.hash(HASH_ITERATIONS, MEMORY_COST_KB, PARALLELISM, password);
+    }
+
+    /**
+     * Verifies the given password against the stored hash.
+     *
+     * @param password the password to verify
+     * @param hash the stored hash
+     * @return true if the password matches the hash, false otherwise
+     */
+    public static boolean verifyPassword(char[] password, String hash) {
+        return argon2.verify(hash, password);
+    }
+
+    /**
+     * Checks if the given hash needs to be rehashed based on the current
+     * parameters.
+     *
+     * @param hash the hash to check
+     * @return true if the hash needs to be rehashed, false otherwise
+     */
+    public static boolean needsRehash(String hash) {
+        return argon2.needsRehash(hash, HASH_ITERATIONS, MEMORY_COST_KB, PARALLELISM);
+    }
+
+    /**
+     * Checks whether the given hash is hashed using Argon2.
+     *
+     * @param hash the hash to check
+     * @return true if the hash is hashed with Argon2, false otherwise
+     */
+    public static boolean isArgon2Hashed(String hash) {
+        return hash != null && hash.startsWith("$argon2");
+    }
+
+    /**
+     * Wipes the contents of the given character array. This should be called
+     * when a plaintext password is no longer needed so it is not kept in memory.
+     *
+     * @param array the array to wipe
+     */
+    public static void wipeArray(char[] array) {
+        argon2.wipeArray(array);
+    }
+}

src/main/java/com/threerings/user/OOOUser.java

@@ -8,11 +8,10 @@ import java.util.List;
 import java.util.StringTokenizer;
 
 import com.google.common.collect.ImmutableList;
-
 import com.samskivert.jdbc.jora.FieldMask;
+import com.samskivert.servlet.user.Password;
 import com.samskivert.servlet.user.User;
 import com.samskivert.util.ArrayIntSet;
-
 import static com.threerings.user.Log.log;
 
 /**
@@ -341,6 +340,51 @@ public class OOOUser extends User
         }
     }
 
+    @Override
+    public void setPassword(String password) {
+        // we might want to consider disabling this in favor of directly using char[]
+        // because char[] can be wiped when it's done being used for security,
+        // but for now, we'll keep it as is to not break existing functionality
+        setPassword(password.toCharArray());
+    }
+
+    /**
+     * Sets the user's password and wipes the plaintext password from memory.
+     *
+     * @param password the password to set
+     */
+    public void setPassword(char[] password) {
+        String encrypted = Crypto.hashPassword(password);
+        setPassword(Password.makeFromCrypto(encrypted));
+    }
+
+    /**
+     * Checks the user's password against the provided plaintext password.
+     *
+     * @param password the plaintext password to check
+     * @return true if the password is correct, false otherwise
+     */
+    public boolean checkPassword(char[] password) {
+        return Crypto.verifyPassword(password, this.password);
+    }
+
+    /**
+     * Checks whether the user's password is hashed using Argon2.
+     */
+    public boolean isArgon2Hashed() {
+        return Crypto.isArgon2Hashed(password);
+    }
+
+    /**
+     * Checks if the user's password needs to be rehashed based on the current
+     * parameters.
+     *
+     * @return true if the password needs to be rehashed, false otherwise
+     */
+    public boolean needsRehash() {
+        return !isArgon2Hashed() || Crypto.needsRehash(this.password);
+    }
+
     /**
      * Set all the spots that this user has recieved.
      */

src/main/java/com/threerings/user/OOOUserRepository.java

@@ -1589,7 +1589,7 @@ public class OOOUserRepository extends UserRepository
         String[] usersSchema = {
             "userId INTEGER(10) PRIMARY KEY NOT NULL AUTO_INCREMENT",
             "username VARCHAR(255) NOT NULL",
-            "password VARCHAR(32) NOT NULL",
+            "password VARCHAR(128) NOT NULL",
             "email VARCHAR(128) NOT NULL",
             "realname VARCHAR(128) NOT NULL",
             "created DATE NOT NULL",
@@ -1605,6 +1605,12 @@ public class OOOUserRepository extends UserRepository
         };
         JDBCUtil.createTableIfMissing(conn, "users", usersSchema, "");
 
+        // give the password a longer length to allow more secure hashing
+        int passwordLength = JDBCUtil.getColumnSize(conn, "users", "password");
+        if (passwordLength < 128) {
+            JDBCUtil.changeColumn(conn, "users", "password", "password VARCHAR(128) NOT NULL");
+        }
+
         String[] historySchema = {
             "userId INTEGER(10) PRIMARY KEY NOT NULL",
             "username VARCHAR(255) NOT NULL",