How to use a JPA Attribute Converter to encrypt your data (http://www.thoughts-on-java.org/2014/06/how-to-use-jpa-type-converter-to.html)

CreditCard.java

@Entity
public class CreditCard {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    private String ccNumber;

    private String name;

    ...
}

CryptoConverter.java

@Converter
public class CryptoConverter implements AttributeConverter<String, String> {

    private static final String ALGORITHM = "AES/ECB/PKCS5Padding";
    private static final byte[] KEY = "MySuperSecretKey".getBytes();

    @Override
    public String convertToDatabaseColumn(String ccNumber) {
      // do some encryption
      Key key = new SecretKeySpec(KEY, "AES");
      try {
         Cipher c = Cipher.getInstance(ALGORITHM);
         c.init(Cipher.ENCRYPT_MODE, key);
         return Base64.encodeBytes(c.doFinal(ccNumber.getBytes()));
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
    }

    @Override
    public String convertToEntityAttribute(String dbData) {
      // do some decryption
      Key key = new SecretKeySpec(KEY, "AES");
      try {
        Cipher c = Cipher.getInstance(ALGORITHM);
        c.init(Cipher.DECRYPT_MODE, key);
        return new String(c.doFinal(Base64.decode(dbData)));
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
}

orm.xml

<entity-mappings version="2.1"
        xmlns="http://xmlns.jcp.org/xml/ns/persistence/orm"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence/orm_2_1.xsd">

    <entity class="blog.thoughts.on.java.jpa21.enc.entity.CreditCard">
        <convert converter="blog.thoughts.on.java.jpa21.enc.converter.CryptoConverter" attribute-name="ccNumber"/>
    </entity>
</entity-mappings>