数据库安全

第 5 章 数据库安全

目录

5.1. 保护表

5.2. 保护表字段

5.3. 时间一致性

5.4. 为数据安全而分库

5.5. 内容版本控制,撰改留痕

5.6. 用户/角色认证

5.7. Token 认证

5.8. 数据加密

5.8.1. AES_ENCRYPT / AES_DECRYPT

5.8.2. 加密字段

5.9. 开发加密插件开发

5.1. 保护表

保护表中的数据不被删除，当记录被用户删除时会提示"Permission denied" 权限拒绝

CREATE DEFINER=`root`@`192.168.%` TRIGGER `member_before_delete` BEFORE DELETE ON `member` FOR EACH ROW BEGIN
	SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Permission denied', MYSQL_ERRNO = 1001;
END

5.2. 保护表字段

通过触发器，使之无法修改某些字段的数据，同时不影响修改其他字段。

DROP TRIGGER IF EXISTS `members`;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='';
DELIMITER //
CREATE TRIGGER `members` BEFORE UPDATE ON `members` FOR EACH ROW BEGIN
	set new.name 		= old.name;
	set new.cellphone 	= old.cellphone;
	set new.email 		= old.email;
    set new.password 	= old.password;
END//
DELIMITER ;
SET SQL_MODE=@OLD_SQL_MODE;

再举一个例子

CREATE TABLE `account` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
	`user` VARCHAR(50) NOT NULL DEFAULT '0',
	`cash` FLOAT NOT NULL DEFAULT '0',
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

每一次数据变化新增一条数据

INSERT INTO `test`.`account` (`user`, `cash`) VALUES ('neo', -10);
INSERT INTO `test`.`account` (`user`, `cash`) VALUES ('neo', -5);
INSERT INTO `test`.`account` (`user`, `cash`) VALUES ('neo', 30);
INSERT INTO `test`.`account` (`user`, `cash`) VALUES ('neo', -20);

保护用户的余额不被修改

DROP TRIGGER IF EXISTS `account`;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='';
DELIMITER //
CREATE TRIGGER `account` BEFORE UPDATE ON `account` FOR EACH ROW BEGIN
	set new.cash 		= old.cash;
END//
DELIMITER ;
SET SQL_MODE=@OLD_SQL_MODE;

5.3. 时间一致性

经常会因为每个服务器的时间不同，导致插入数据有问题，虽然可以采用ntp服务同步时间，但由于各种因素仍然会出问题，怎么解决？我建议以数据库时间为准。

MySQL 5.6 之前的版本

默认值为当前时间

CREATE TABLE `tdate` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`ctime` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
	`mtime` TIMESTAMP NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '修改时间',
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

MySQL不允许一个表拿有两个默认时间。我一无法兼顾修改时间，我们舍弃创建时间，当有数据变化ON UPDATE CURRENT_TIMESTAMP自动修改时间

CREATE TABLE `tdate` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`ctime` TIMESTAMP NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '创建时间',
	`mtime` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

插入创建时间 insert into tdate(ctime) values(CURRENT_TIMESTAMP); 不要采用 insert into tdate(ctime) values('2013-12-02 08:20:06');这种方法，尽量让数据库处理时间。

MySQL 5.6 之后版本，可以实现创建时间为系统默认，修改时间创建的时候默认为空，当修改数据的时候更新时间。

CREATE TABLE `tdate` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`ctime` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
	`mtime` TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

5.4. 为数据安全而分库

我们通常使用一个数据库开发，该数据库包含了前后台所有的功能，我建议将前后台等等功能进行分库然后对应各种平台分配用户权限，例如

我们创建三个数据库cms,frontend,backend 同时对应创建三个用户 cms,frontend,backend 三个用户只能分别访问自己的数据库，注意在系统的设计之初你要考虑好这样的划分随之系统需要做相应的调整。

CREATE DATABASE `cms` /*!40100 COLLATE 'utf8_general_ci' */;
CREATE DATABASE `frontend` /*!40100 COLLATE 'utf8_general_ci' */;
CREATE DATABASE `backend` /*!40100 COLLATE 'utf8_general_ci' */;

backend 负责后台，权限最高

mysql> SHOW GRANTS FOR 'backend'@'localhost';
+--------------------------------------------------------------------------------------+
| Grants for backend@localhost                                                         |
+--------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'backend'@'localhost'                                          |
| GRANT SELECT, INSERT, UPDATE, DELETE ON `cms`.* TO 'backend'@'localhost'             |
| GRANT SELECT, INSERT, UPDATE, DELETE ON `frontend`.* TO 'backend'@'localhost'        |
| GRANT SELECT, INSERT, UPDATE, DELETE, CREATE ON `backend`.* TO 'backend'@'localhost' |
+--------------------------------------------------------------------------------------+
4 rows in set (0.04 sec)

frontend 是前台权限，主要是用户用户中心，用户注册，登录，用户信息资料编辑，查看新闻等等

mysql> SHOW GRANTS FOR 'frontend'@'localhost';
+------------------------------------------------------------------------+
| Grants for frontend@localhost                                          |
+------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'frontend'@'localhost'                           |
| GRANT SELECT, INSERT, UPDATE ON `frontend`.* TO 'frontend'@'localhost' |
| GRANT SELECT ON `cms`.`news` TO 'frontend'@'localhost'                 |
+------------------------------------------------------------------------+
3 rows in set (0.00 sec)

cms 用户是网站内容管理，主要负责内容更新，但登陆CMS后台需要`backend`.`Employees`表用户认证，所以他需要读取权限，但不允许修改其中的数据。

mysql> SHOW GRANTS FOR 'cms'@'localhost';
+----------------------------------------------------------------------+
| Grants for cms@localhost                                             |
+----------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'cms'@'localhost'                              |
| GRANT SELECT, INSERT, UPDATE, DELETE ON `cms`.* TO 'cms'@'localhost' |
| GRANT SELECT ON `backend`.`Employees` TO 'cms'@'localhost'           |
+----------------------------------------------------------------------+
3 rows in set (0.00 sec)

5.5. 内容版本控制,撰改留痕

主表

CREATE TABLE `article` (
	`article_id` MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT,
	`cat_id` SMALLINT(5) NOT NULL DEFAULT '0',
	`title` VARCHAR(150) NOT NULL DEFAULT '',
	`content` LONGTEXT NOT NULL,
	`author` VARCHAR(30) NOT NULL DEFAULT '',
	`keywords` VARCHAR(255) NOT NULL DEFAULT '',
	PRIMARY KEY (`article_id`),
	INDEX `cat_id` (`cat_id`)
)
ENGINE=MyISAM
ROW_FORMAT=DEFAULT
AUTO_INCREMENT=1

用于记录每次修改变动，通过该表，可以追朔数据库记录被什么时候修改过，修改了那些内容。

CREATE TABLE `article_history` (
	`id` MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT,
	`article_id` MEDIUMINT(8) UNSIGNED NOT NULL,
	`cat_id` SMALLINT(5) NOT NULL DEFAULT '0',
	`title` VARCHAR(150) NOT NULL DEFAULT '',
	`content` LONGTEXT NOT NULL,
	`author` VARCHAR(30) NOT NULL DEFAULT '',
	`keywords` VARCHAR(255) NOT NULL DEFAULT '',
	PRIMARY KEY (`id`),
	INDEX `article_id` (`article_id`)
)
ENGINE=MyISAM
ROW_FORMAT=DEFAULT
AUTO_INCREMENT=1

版本控制触发器

DROP TRIGGER article_history;

DELIMITER //
CREATE TRIGGER article_history BEFORE update ON article FOR EACH ROW
BEGIN
	INSERT INTO article_history SELECT * FROM article WHERE article_id = OLD.article_id;
END; //
DELIMITER;

进一步优化，我们可以为 history 历史表增加时间字段，用于记录被撰改那一时刻的时间。

CREATE TABLE `article_history` (
	`id` MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT,
	`article_id` MEDIUMINT(8) UNSIGNED NOT NULL,
	`cat_id` SMALLINT(5) NOT NULL DEFAULT '0',
	`title` VARCHAR(150) NOT NULL DEFAULT '',
	`content` LONGTEXT NOT NULL,
	`author` VARCHAR(30) NOT NULL DEFAULT '',
	`keywords` VARCHAR(255) NOT NULL DEFAULT '',
	`ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'Created Time',
  	`mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT 'Modified Time',
	PRIMARY KEY (`id`),
	INDEX `article_id` (`article_id`)
)
ENGINE=MyISAM
ROW_FORMAT=DEFAULT
AUTO_INCREMENT=1

我们还可以为该表（article_history）增加出发器，任何修改将被拒绝.

5.6. 用户/角色认证

本小节我们实现一个功能，当用户插入，修改或者删除数据时，判断该操作是否具备应有的权限。如果权限不符合就拒绝操作同时提示用户。

CREATE TABLE `staff` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '员工ID',
	`name` VARCHAR(50) NOT NULL COMMENT '员工名字',
	PRIMARY KEY (`id`)
)
COMMENT='员工表'
COLLATE='utf8_general_ci'
ENGINE=InnoDB;


INSERT INTO `staff` (`id`, `name`) VALUES
	(1, 'Neo'),
	(2, 'Luke'),
	(2, 'Jack');

staff 是员工表与下面的staff_has_role配合使用，形成员工与权限一对多关系。

CREATE TABLE `staff_has_role` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
	`staff_id` INT(10) UNSIGNED NOT NULL COMMENT '员工ID',
	`role` ENUM('Create','Update','Delete') NOT NULL COMMENT '角色',
	PRIMARY KEY (`id`),
	INDEX `FK_staff_has_role_staff` (`staff_id`),
	CONSTRAINT `FK_staff_has_role_staff` FOREIGN KEY (`staff_id`) REFERENCES `staff` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

INSERT INTO `staff_has_role` (`id`, `staff_id`, `role`) VALUES
	(1, 1, 'Create'),
	(2, 1, 'Delete'),
	(3, 1, 'Update'),
	(4, 2, 'Delete'),
	(5, 3, 'Create');
	(6, 3, 'Update');

权限表可以进一步优化，角色拥有组功能，实现颗粒度更细的权限控制，有情趣看前面的相关章节。

CREATE TABLE `product` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '唯一ID',
	`name` VARCHAR(10) NOT NULL COMMENT '名称',
	`sn` VARCHAR(10) NOT NULL COMMENT '序列号',
	`price` FLOAT NOT NULL COMMENT '价格',
	`amount` SMALLINT(6) NOT NULL COMMENT '数量',
	`staff_id` INT(10) UNSIGNED NOT NULL COMMENT '员工ID',
	`ctime` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
	`mtime` TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
	PRIMARY KEY (`id`),
	UNIQUE INDEX `sn` (`sn`),
	INDEX `FK_product_staff` (`staff_id`),
	CONSTRAINT `FK_product_staff` FOREIGN KEY (`staff_id`) REFERENCES `staff` (`id`)
)
COMMENT='产品表'
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

以产品表为例，这里要实现的是对产品表记录的权限控制。例如Neo有用插入，修改和删除权限，Luke的Create与Update权限被吊销，只能删除他之前创建的数据。而Jack只有能创建于更新数据。

下面的三个触发器完成具体的权限控制。同样你可以进一步优化下面的代码的权限颗粒度，使之能控制到具体列，甚至具体的记录。

CREATE DEFINER=`root`@`%` TRIGGER `product_before_delete` BEFORE DELETE ON `product` FOR EACH ROW BEGIN
	if not exists(select id from staff where id=OLD.staff_id and role="delete") then
		SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Permission denied', MYSQL_ERRNO = 1001;
	end if;
END

CREATE DEFINER=`root`@`%` TRIGGER `product_before_insert` BEFORE INSERT ON `product` FOR EACH ROW BEGIN
	 if not exists(select id from staff where id=NEW.staff_id and role="create") then
	       SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "The staff's role is not correct or it does not exist.", MYSQL_ERRNO = 1001;
	 end if;
END

CREATE DEFINER=`root`@`%` TRIGGER `product_before_update` BEFORE UPDATE ON `product` FOR EACH ROW BEGIN
	if not exists(select id from staff where id=NEW.staff_id and role="update") then
		SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "The staff's role cannot update data.", MYSQL_ERRNO = 1001;
	end if;
END

Neo 测试如下

INSERT INTO `test`.`product` (`name`, `sn`, `price`, `amount`, `staff_id`, `ctime`) VALUES ('Iphone', '678624', '5000', '77', '1', '2010-08-18 15:38:23');
SELECT LAST_INSERT_ID();

UPDATE `test`.`product` SET `name`='HTC', `sn`='5544467', `price`='2000' WHERE  `id`=2;

DELETE FROM `test`.`product` WHERE  `id`=1;

Luke 测试如下：

INSERT INTO `test`.`product` (`name`, `sn`, `price`, `amount`, `staff_id`) VALUES ('Nokia', '65722', '800', '55', '2');
/* SQL错误（1001）：The staff's role is not correct or it does not exist. */

UPDATE `test`.`product` SET `name`='HTC', `sn`='5544467', `price`='2000', staff_id=2 WHERE  `id`=2;
/* SQL错误（1001）：The staff's role cannot update data. */

5.7. Token 认证

我们在staff表的基础上增加 token 字段

CREATE TABLE `staff` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '员工ID',
	`name` VARCHAR(50) NOT NULL COMMENT '员工名字',
	`token` VARCHAR(32) NOT NULL COMMENT 'Token 校验',
	PRIMARY KEY (`id`)
)
COMMENT='员工表'
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

插入数据的时候增加一些干扰字符串，这里使用concat(NEW.id,'+',NEW.name,'-')

CREATE DEFINER=`root`@`%` TRIGGER `staff_before_insert` BEFORE INSERT ON `staff` FOR EACH ROW BEGIN

if md5(concat(NEW.id,'+',NEW.name,'-')) != NEW.token then
		SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Permission denied', MYSQL_ERRNO = 1001;
	end if;

END

注意表权限可以授权给用户，触发器权限不让普通用户查看。否则用户看到 concat(NEW.id,'+',NEW.name,'-') 就没有意义了。

下面开始测试：

INSERT INTO `test`.`staff` (`name`, `token`) VALUES ('John', '678797066');
/* SQL错误（1001）：Permission denied */

下面再测试，首先生成一个正确的tokon, 然后使用该token插入数据：

-- 通过下面语句生成一个 Token
select md5(concat('5','+','Jam','-')) as token;

-- 使用上面的 Token 插入数据
INSERT INTO `test`.`staff` (`id`, `name`, `token`) VALUES (5, 'Jam', '1b033ce21cbadacabc9f0c38fb58dbb2');

SELECT * FROM `test`.`staff` WHERE `id` = 5;

开发注意事项, Token 生成算法要保密，不要使用下面SQL提交数据

INSERT INTO `test`.`staff` (`id`, `name`, `token`) VALUES (5, 'Jam', md5(concat('5','+','Jam','-')));

应该分两步，一是计算Token，二是插入数据。可以将Token计算交给程序而不是SQL，并且封装在。jar(Java)中或者。so(PHP 扩展中).

5.8. 数据加密

数据库中有很多敏感字段，不允许随意查看，例如开发人员，运维人员，甚至DBA数据库管理员。另外加密主要是防止被黑客脱库（盗走）

敏感数据加密有很多办法，可以用数据库内部加密函数，也可以在外部处理后写入数据库。加密算法有很多种，但通常两类比较常用，一种是通过key加密解密，另一种是通过证书加密解密。

通常程序员负责写程序，程序交给运维配置，运维将key设置好，运维不能有数据库权限，DBA只能登陆数据库，没有key权限。

5.8.1. AES_ENCRYPT / AES_DECRYPT

这里介绍AES加密与解密简单用法

mysql> select AES_ENCRYPT('helloworld','key');
+---------------------------------+
| AES_ENCRYPT('helloworld','key') |
+---------------------------------+
|                                 |
+---------------------------------+
1 row in set (0.00 sec)

mysql> select AES_DECRYPT(AES_ENCRYPT('helloworld','key'),'key');
+----------------------------------------------------+
| AES_DECRYPT(AES_ENCRYPT('helloworld','key'),'key') |
+----------------------------------------------------+
| helloworld                                         |
+----------------------------------------------------+
1 row in set (0.00 sec)

mysql>

5.8.2. 加密字段

加密数据入库

CREATE TABLE `encryption` (
	`mobile` VARBINARY(16) NOT NULL,
	`key` VARCHAR(32) NOT NULL
)
ENGINE=InnoDB;

INSERT INTO encryption(`mobile`,`key`)VALUES( AES_ENCRYPT('13691851789',md5('13691851789')), md5('13691851789')) 
select AES_DECRYPT(mobile,`key`), length(mobile) from encryption;

这里方便演示将key 写入了数据库，实际应用key应该存储在应用程序配置文件中。通常能把获得key的人不应该用数据库权限。

5.9. 开发加密插件开发

数据库内部提供的摘要函数MD5/SHA/CRC与现有的AES/DES加密函数以及不能满足我们的需求，所以我们有必要开发外挂插件实现数据加密。

这里有一个例子，是我早年开发的 https://github.com/netkiller/mysql-safenet-plugin 这个UDF是链接 Safenet设备，实现数据库加密记录。

saftnet.h

my_bool safenet_encrypt_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
char *safenet_encrypt(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned long *length, char *is_null, char *error);
void safenet_encrypt_deinit(UDF_INIT *initid);

my_bool safenet_decrypt_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
char *safenet_decrypt(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned long *length, char *is_null, char *error);
void safenet_decrypt_deinit(UDF_INIT *initid);

my_bool safenet_config_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
char *safenet_config(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned long *length, char *is_null, char *error);
void safenet_config_deinit(UDF_INIT *initid);

safenet.c

/*
Homepage: http://netkiller.github.io/
Author: netkiller<netkiller@msn.com>
*/

#include <mysql.h>
#include <string.h>

#include <stdio.h>
#include <stdlib.h>
#include <curl/curl.h>
#include "safenet.h"

#define SAFENET_URL "http://localhost/safe/interface" 
#define SAFENET_KEY "Web01-key" 

char *safe_url;
char *safe_key;


void get_safenet_env(){
    if (getenv("SAFENET_URL")){
	safe_url = getenv("SAFENET_URL");
    }else{
	safe_url = SAFENET_URL;
    }
    if (getenv("SAFENET_KEY")){
	safe_key = getenv("SAFENET_KEY");
    }else{
	safe_key = SAFENET_KEY;
    }
}

/* CURL FUNCTION BEGIN*/
struct string {
  char *ptr;
  size_t len;
};

void init_string(struct string *s) {
  s->len = 0;
  s->ptr = malloc(s->len+1);
  if (s->ptr == NULL) {
    fprintf(stderr, "malloc() failed
");
    exit(EXIT_FAILURE);
  }
  s->ptr[0] = '';
}

size_t writefunc(void *ptr, size_t size, size_t nmemb, struct string *s)
{
  size_t new_len = s->len + size*nmemb;
  s->ptr = realloc(s->ptr, new_len+1);
  if (s->ptr == NULL) {
    fprintf(stderr, "realloc() failed
");
    exit(EXIT_FAILURE);
  }
  memcpy(s->ptr+s->len, ptr, size*nmemb);
  s->ptr[new_len] = '';
  s->len = new_len;

  return size*nmemb;
}

char * safenet(char *url, char *mode, char *key, char *in )
{ 
    CURL *curl;
    CURLcode res;
    char *fields;
    char *data;

//  curl_global_init(CURL_GLOBAL_ALL);
 
    /* get a curl handle */ 
    curl = curl_easy_init();
    if(curl) {
        struct string s;
        init_string(&s); 
        
        asprintf(&fields, "mode=%s&keyname=%s&input=%s", mode, key, in);    
    
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_USERAGENT, "safenet/1.0 by netkiller <netkiller@msn.com>");
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writefunc);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &s);
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, fields);
     
        /* Perform the request, res will get the return code */ 
        res = curl_easy_perform(curl);
        /* Check for errors */ 
        if(res != CURLE_OK)
          fprintf(stderr, "curl_easy_perform() failed: %s
",
                  curl_easy_strerror(res));
     
        asprintf(&data, "%s", s.ptr);
        //printf("Encrypt: %s
", data);
    
        free(s.ptr);
        /* always cleanup */ 
        curl_easy_cleanup(curl);
    }
    else{
	strcpy(data,"");
    }

    return data;
  //curl_global_cleanup();
}
/* CURL FUNCTION END*/

/* ------------------------ safenet encrypt ----------------------------- */

my_bool safenet_encrypt_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
{

  if (args->arg_count != 1)
  {
    strncpy(message,
            "two arguments must be supplied: safenet_encrypt('<data>').",
            MYSQL_ERRMSG_SIZE);
    return 1;
  }
  get_safenet_env(); 
  args->arg_type[0]= STRING_RESULT;

  return 0;
}

char *safenet_encrypt(UDF_INIT *initid, UDF_ARGS *args,
                __attribute__ ((unused)) char *result,
               unsigned long *length,
                __attribute__ ((unused)) char *is_null,
                __attribute__ ((unused)) char *error)
{

    char *data;
    data = safenet(safe_url, "encrypt", safe_key, args->args[0]);
    *length = strlen(data);
    return ((char *)data);

}

void safenet_encrypt_deinit(UDF_INIT *initid)
{
  return;
}

/* ------------------------ safenet decrypt ----------------------------- */

my_bool safenet_decrypt_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
{

  if (args->arg_count != 1)
  {
    strncpy(message,
            "two arguments must be supplied: safenet_decrypt('<data>').",
            MYSQL_ERRMSG_SIZE);
    return 1;
  }

  get_safenet_env();
  args->arg_type[0]= STRING_RESULT;

  return 0;
}

char *safenet_decrypt(UDF_INIT *initid, UDF_ARGS *args,
                __attribute__ ((unused)) char *result,
               unsigned long *length,
                __attribute__ ((unused)) char *is_null,
                __attribute__ ((unused)) char *error)
{

    char *data;
    if(strlen(args->args[0]) != 512){
        data = args->args[0];
    }else{
        data = safenet(safe_url, "decrypt", safe_key, args->args[0]);
    }
    *length = strlen(data);
    return ((char *)data);

}

void safenet_decrypt_deinit(UDF_INIT *initid)
{
  return;
}

/* ------------------------ safenet config ----------------------------- */

my_bool safenet_config_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
{

    get_safenet_env();
    return 0;
}

char *safenet_config(UDF_INIT *initid, UDF_ARGS *args,
                __attribute__ ((unused)) char *result,
               unsigned long *length,
                __attribute__ ((unused)) char *is_null,
                __attribute__ ((unused)) char *error)
{

  char *config;
  asprintf(&config, "SAFENET_URL=%s, SAFENET_KEY=%s", safe_url, safe_key);
  *length = strlen(config);
  return ((char *)config);
}

void safenet_config_deinit(UDF_INIT *initid)
{
   return;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
PROJECT(safenet)
ADD_LIBRARY(safenet SHARED safenet.c)
INCLUDE_DIRECTORIES(/usr/include/mysql)
TARGET_LINK_LIBRARIES(safenet curl)
INSTALL(PROGRAMS libsafenet.so DESTINATION /usr/lib64/mysql/plugin/)

Installation Plugin

yum install -y libcurl-devel

cd src
cmake .
make 
make install

cat > /etc/sysconfig/mysqld <<EOF
export SAFENET_URL=http://host.localdomain/safe/interface
export SAFENET_KEY=Web01-key
EOF

Create Function

create function safenet_encrypt returns string soname 'libsafenet.so';
create function safenet_decrypt returns string soname 'libsafenet.so';
create function safenet_config returns string soname 'libsafenet.so';

Example

mysql> select safenet_encrypt('Helloworld!!!');
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| safenet_encrypt('Helloworld!!!')                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|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|
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.58 sec)

mysql> select safenet_decrypt(safenet_encrypt('Helloworld!!!'));
+---------------------------------------------------+
| safenet_decrypt(safenet_encrypt('Helloworld!!!')) |
+---------------------------------------------------+
| Helloworld!!!                                     |
+---------------------------------------------------+
1 row in set (0.31 sec)

mysql> select safenet_config();

Drop Function

drop function safenet_encrypt;
drop function safenet_decrypt;
drop function safenet_config;

转自：http://my.oschina.net/neochen/blog/735910