撒点盐Salt

Salt is a way to strengthen the security of encrypted data. It is a random string added to the data before it is encrypted, causing repetition of text in the clear to appear different when encrypted. Salt thus removes one method attackers use to steal data, namely, matching patterns of encrypted text.


To add or remove salt from encrypted columns, you again use the ALTER TABLE MODIFY command with either the SALT or NO SALT parameter specified with the ENCRYPT clause. Example 3-3 and Example 3-4 illustrate such commands.


Example 3-3 Adding Salt to an Encrypted Column


ALTER TABLE employee MODIFY (first_name ENCRYPT SALT);
Example 3-4 Removing Salt from an Encrypted Column


ALTER TABLE employee MODIFY (first_name ENCRYPT NO SALT);
To remove salt from an encrypted column before indexing it, use the syntax shown in Example 3-4. This command also re-encrypts the data.




Creating a Table with an Encrypted Column Using a Non-Default Algorithm and No Salt
By default, transparent data encryption adds salt to cleartext before encrypting it. This makes it harder for attackers to steal the data through a brute force attack.


However, if you plan to index the encrypted column, you must use NO SALT. Example 3-6 shows how to specify the NO SALT parameter with the SQL ENCRYPT clause (empID NUMBER ENCRYPT NO SALT). It also shows the syntax for specifying a different encryption algorithm (salary NUMBER(6) ENCRYPT USING '3DES168'). Note that the string which specifies the algorithm must be enclosed in single quotation marks.


Example 3-6 Creating a New Table with an Encrypted Column Using 3DES168 and NO SALT


CREATE TABLE employee (
     first_name VARCHAR2(128),
     last_name VARCHAR2(128),
     empID NUMBER ENCRYPT NO SALT,
     salary NUMBER(6) ENCRYPT USING '3DES168'
);

当前题目:撒点盐Salt
当前链接:http://bzwzjz.com/article/ppgdse.html

其他资讯

Copyright © 2007-2020 广东宝晨空调科技有限公司 All Rights Reserved 粤ICP备2022107769号
友情链接: 高端网站设计 网站设计制作 高端定制网站设计 网站设计公司 重庆外贸网站建设 成都网站设计 教育网站设计方案 成都营销网站建设 成都网站建设公司 网站建设 成都定制网站建设 app网站建设 重庆企业网站建设 重庆网站建设 梓潼网站设计 网站制作 成都网站设计 手机网站制作 成都网站设计 成都网站设计 成都网站建设公司 成都定制网站建设