Hibernate Encryption of Database Completely Transparent to Application

Question

I\'m working on a Grails 1.0.4 project that has to be released in less than 2 weeks, and the customer just came up with a requirement that all data in the database should be enc

Answer 1

Another option is to use a JDBC driver that encrypts/decrypts data on the fly, two way. Bear in mind that any solution will probably invalidate searches by encrypted fields.

IMHO the best solution is the one proposed by longneck, it will make everything much easier, from administration to development. Besides, bear in mind that any solution with client-side encryption will render all your db data unusable outside of the client, ie, you will not be able to use nice tools like a jdbc client or MySQL query browser, etc.

Answer 2

Generated ids, version, mapped foreign keys - basically everything maintained by Hibernate - are out unless you intend to declare custom CRUD for all of your classes and manually encrypt them in queries.

For everything else you've got a couple of choices:

1. @PostLoad and @PrePersist entity listeners will take care of all non-query operations.
2. Implementing custom String / Long / Integer / etc... types to handle encryption will take care of both query and CRUD operations; however the mapping will become rather messy.
3. You can write a thin wrapper around a JDBC driver (as well as Connection / Statement / PreparedStatement / ResultSet / etc...) to do the encryption for you.

As far as queries go you'll have to handle encryption manually (unless you're going with #2 above) but you should be able to do so via a single entry point. I'm not sure how (or if) Grails deals with this, but using Spring, for example, it would be as easy as extending HibernateTemplate.

Answer 3

If the customer is worried about someone physically walking away with the hard drive then using a full disk solution like Truecrypt should work. If there worried about traffic being sniffed then take a look at this part of the mysql documentation on ssl over JDBC. Remember if someone compromises your server all bets are off.

Answer 4

the customer could easily do this without changing a thing in your application.

first, encrypt the communications between the server by turning on SSL in the mysql layer, or use an SSH tunnel.

second, store the mysql database on an encrypted volume.

any attack that can expose the filesystem of the mysql database or the credentials needed to log in to the mysql server is not mitigated by encrypting the data since that same attack can be used to retrieve the encryption key from the application itself.

Answer 5

If you end doing the work in the application, you can use Hibernate custom types and it wouldn't add that many changes to your code.

Here's an encrypted string custom type that I've used:

import org.hibernate.usertype.UserType
import org.apache.log4j.Logger

import java.sql.PreparedStatement
import java.sql.ResultSet
import java.sql.SQLException
import java.sql.Types

class EncryptedString implements UserType {

  // prefix category name with 'org.hibernate.type' to make logging of all types easier
  private final Logger _log = Logger.getLogger('org.hibernate.type.com.yourcompany.EncryptedString')

  Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws SQLException {
    String value = rs.getString(names[0])

    if (!value) {
      _log.trace "returning null as column: $names[0]"
      return null
    }

    _log.trace "returning '$value' as column: $names[0]"
    return CryptoUtils.decrypt(value)
  }

  void nullSafeSet(PreparedStatement st, Object value, int index) throws SQLException {
    if (value) {
      String encrypted = CryptoUtils.encrypt(value.toString())
      _log.trace "binding '$encrypted' to parameter: $index"
      st.setString index, encrypted
    }
    else {
      _log.trace "binding null to parameter: $index"
      st.setNull(index, Types.VARCHAR)
    }
  }

  Class<String> returnedClass() { String }

  int[] sqlTypes() { [Types.VARCHAR] as int[] }

  Object assemble(Serializable cached, Object owner) { cached.toString() }

  Object deepCopy(Object value) { value.toString() }

  Serializable disassemble(Object value) { value.toString() }

  boolean equals(Object x, Object y) { x == y }

  int hashCode(Object x) { x.hashCode() }

  boolean isMutable() { true }

  Object replace(Object original, Object target, Object owner) { original }
}

and based on this it should be simple to create similar classes for int, long, etc. To use it, add the type to the mapping closure:

class MyDomainClass {

  String name
  String otherField

  static mapping = {
    name type: EncryptedString
    otherField type: EncryptedString
  }
}

I omitted the CryptoUtils.encrypt() and CryptoUtils.decrypt() methods since that's not Grails-specific. We're using AES, e.g. "Cipher cipher = Cipher.getInstance('AES/CBC/PKCS5Padding')". Whatever you end up using, make sure it's a 2-way crypto, i.e. don't use SHA-256.

Answer 6

Well it has been a long time since I've asked the question. In the meantime, thanks for all the answers. They were great when dealing with the original idea of encrypting the entire database, but the requirement changed to only encrypting sensitive user info, like name and address. So the solution was something like the code down below.

We've implemented an Encrypter which reads the encryption method from the record ( so there can be different encryption per record) and use it to connect transient duplicate fields to the ones encrypted in the database. The added bonus/drawbacks are:

• The data is also encrypted in memory, so every access to the method getFirstName descrypts the data (I guess there is a way to cache decrypted data, but I dont need it in this case)

• Encrypted fields cannot be used with default grails/hibernate methods for search through database, we've made custom methods in services that get data, encrypt it and then use the encrypted data in the where clause of a query. It's easy when using User.withCriteria

  class User {

  byte[] encryptedFirstName
  byte[] encryptedLastName
  byte[] encryptedAddress
  
  Date dateCreated // automatically set date/time when created
  Date lastUpdated // automatically set date/time when last updated
  
  EncryptionMethod encryptionMethod = ConfigurationHolder.config.encryption.method
  
  def encrypter = Util.encrypter
  
  static transients = [ 
  'firstName', 
  'lastName', 
  'address',
  'encrypter'
  ]
  
  static final Integer BLOB_SIZE = 1024
  
  static constraints = {
  
      encryptedFirstName maxSize: BLOB_SIZE, nullable: false
      encryptedLastName maxSize: BLOB_SIZE, nullable: false
  
      encryptedAddress maxSize: BLOB_SIZE, nullable: true
  
      encryptionMethod nullable: false
  
  } // constraints
  
  String getFirstName(){
      decrypt('encryptedFirstName')
  }
  
  void setFirstName(String item){     
      encrypt('encryptedFirstName',item)
  }
  
  String getLastName(){
      decrypt('encryptedLastName')
  }
  
  void setLastName(String item){
      encrypt('encryptedLastName',item)       
  }
  
  String getAddress(){
      decrypt('encryptedAddress')
  }
  
  void setAddress(String item){
      encrypt('encryptedAddress',item)        
  }
  
  byte[] encrypt(String name, String value) {
  
      if( null == value ) {
          log.debug "null string to encrypt for '$name', returning null"
          this.@"$name" = null
          return
      }
  
      def bytes = value.getBytes(encrypter.ENCODING_CHARSET)
      def method = getEncryptionMethod()
  
  
      byte[] res 
  
      try {
          res = encrypter.encrypt( bytes, method )            
      } catch(e) {
          log.warn "Problem encrypting '$name' data: '$string'", e
      }
  
      log.trace "Encrypting '$name' with '$method' -> '${res?.size()}' bytes"
  
      this.@"$name" = res
  
  }
  
  String decrypt(String name) {
  
      if(null == this.@"$name") {
          log.debug "null bytes to decrypt for '$name', returning null"
          return null
      }
  
      def res 
      def method = getEncryptionMethod()
  
      try {
          res = new String(encrypter.decrypt(this.@"$name", method), encrypter.ENCODING_CHARSET )
      } catch(e) {
          log.error "Problem decrypting '$name'", e
      }
  
      log.trace "Decrypting '$name' with '$method' -> '${res?.size()}' bytes"
  
      return res
  }
  

  }