Implement the encryption method and test unit.

src/main/java/fr/xephi/authme/security/crypts/description/IPB4.java

@@ -1,35 +1,56 @@
 package fr.xephi.authme.security.crypts.description;
 
+import fr.xephi.authme.ConsoleLogger;
+import fr.xephi.authme.security.crypts.BCryptService;
 import fr.xephi.authme.security.crypts.EncryptionMethod;
 import fr.xephi.authme.security.crypts.HashedPassword;
+import fr.xephi.authme.util.StringUtils;
+
+import java.security.SecureRandom;
 
 
 @Recommendation(Usage.DOES_NOT_WORK)
 @HasSalt(value = SaltType.TEXT)
 public class IPB4 implements EncryptionMethod {
+    SecureRandom random = new SecureRandom();
 
     @Override
     public String computeHash(String password, String salt, String name) {
-        return null;
+        return BCryptService.hashpw(password, "$2a$13$" + salt);
     }
 
     @Override
     public HashedPassword computeHash(String password, String name) {
-        return null;
+        String salt = generateSalt();
+        return new HashedPassword(computeHash(password, salt, name), salt);
     }
 
     @Override
     public boolean comparePassword(String password, HashedPassword hash, String name) {
+        try {
+            return hash.getHash().length() > 3 && BCryptService.checkpw(password, hash.getHash());
+        } catch (IllegalArgumentException e) {
+            ConsoleLogger.showError("Bcrypt checkpw() returned " + StringUtils.formatException(e));
+        }
         return false;
     }
 
     @Override
     public String generateSalt() {
-        return null;
+        StringBuilder sb = new StringBuilder(22);
+        for (int i = 0; i < 22; i++) {
+            char chr;
+            do {
+                chr = (char) (random.nextInt((122 - 48) + 1) + 48);
+            }
+            while ((chr >= 58 && chr <= 64) || (chr >= 91 && chr <= 96));
+            sb.append(chr);
+        }
+        return sb.toString();
     }
 
     @Override
     public boolean hasSeparateSalt() {
-        return false;
+        return true;
     }
 }