sql 2005数据库加密实战

转贴自teched讲师: 牛可

基本概念:

第一层 服务主密钥

备份服务主密钥

backup service master key to file='c:\smk.bak'

encryption by password='P@ssw0rd'

restore service master key from file='c:\smk.bak'

decryption by password='P@ssw0rd'

第二层 数据库主密钥

1)必须先在该数据库上创建数据库主密钥才能使用

create master key encryption by password='P@ssw0rd'

2)使用数据库主密钥

－如果数据库主密钥使用服务密钥进行保护，则在使用时会自动打开

opren master key decryption by password='P@ssw0rd'

3)查看数据库主密钥状态

sys.symmetric_keys

4)备份数据库主密钥

backup master key to file='c:\smk.bak'

encryption by password='P@ssw0rd'

restore master key from file='c:\smk.bak'

decryption by password='P@ssw0rd'

数字证书

创建自签名

create certificate cert_myCert

encryption by password='P@ssw0rd'

with subject='Self Signed Cert',

start_date='1/31/2006'

expiry_date='1/31/2008'

非对称密钥

创建新的密钥对

create asymmetric key asy_Key1

with algorithm=RSA_2048

encryption by password='P@ssw0rd'

对称密钥

创建新的密钥对

create symmetric key SymKeyMarketing3

with algorithm=AES_2048

encryption by certificate asy_Key1

使用对称密钥

使用前必须打开

open symmetric SymKeyMarketing3

decryption by certificate asy_Key1

sys.open_keys

数据列加密

－使用对称密钥加密大量的列数据

－考虑使用证书，非对称密钥保护对称密钥

防止绕过加密数据列的攻击－使用验证器

注:

在加密列上的索引将变得无效

加密数据列的长度增长，建议使用varbinary（max）数据类型

修改已有的dml语句以支持加密的数据列

-----***********示例1 了解数据库加密体系结构*****-----

--************(1) 服务主密钥

--准备工作

--创建测试数据库TestDB

--1)备份服务主密钥

backup service master key to file='g:\smk.bak'

encryption by password='p@ssw0rd'

--2)生成新的主密钥

Alter service master key regenerate

--3)从备份文件还原服务主密钥

Restore service master key from file= file='g:\smk.bak'

encryption by password='p@ssw0rd'

--*************(2) 数据库主密钥

--1)为数据库创建数据库主密钥

create master key encryption by password='p@ssw0rd'

go

--2)查看数据库加密状态

select [name],is_master_key_encrypted_by_server

from sys.databases where name='TestDB'

--3)查看数据库主密钥的信息

select * from sys.symmetric_keys

--4)备份数据库主密钥

backup master key

to file='g:\testdbkey.bak'

encryption by password='p@ssw0rd'

--5)删除服务主密钥对数据库主密钥的保护

--创建非对称密钥成功,自动使用服务主密钥解密并使用该数据库主密钥

create asymmetric key asy_Testkey1 with algorithm=RSA_1024

go

--删除服务主密钥对数据库主密钥的保护

alter master key

drop encryption by service master key

go

--查看数据库加密状态

select [name],is_master_key_encrypted_by_server

from sys.databases where name='TestDB'

--创建非对称密钥失败,因为数据库主密钥未打开

create asymmetric key asy_Testkey2 with algorithm=RSA_1024

go

--打开数据库主密钥

open master key decryption by password='p@ssw0rd'

select * from sys.openkeys

go

--创建非对称密钥成功

create asymmetric key asy_Testkey2 with algorithm=RSA_1024

go

--恢复服务主密钥对数据库主密钥的保护

alter master key

add encryption by service master key

close master key

go

--*****(3)证书

--1)创建自签名证书

create certificate cert_Testcert

encryption by password='p@ssw0rd'

with subject='TestCert1',

start_date='1/31/2006',

expiry_date='1/31/2008'

go

select * from sys.certificates

--2)从文件导入证书

Create certificate cert_TestCert2

From file=’g:\MSCert.cer’

Go

-- 3)备份导出证书和密钥

backup certificate cert_Testcert

to file='g:\Testcert.cer'

with private key

(decryption by password='p@ssw0rd',

file='g:\TestCert_pvt',--私密钥

encryption by password='p@ssw0rd' )

go

--4)使用证书加解密数据

--加密:使用证书的公钥

declare @cleartext varbinary(200)

declare @cipher varbinary(200)

set @cleartext=convert( varbinary(200),'Test text string')

set @cipher=EncryptByCert(Cert_ID('cert_TestCert'),@cleartext)

select @cipher

--解密:使用证书的私钥

select convert(varchar(200),DecryptByCert(Cert_ID('cert_TestCert'),@cipher,N'p@ssw0rd')) as [cleartext]

--5) 删除证书私钥

alter certificate cert_TestCert

remove private key

go

--加密成功

declare @cleartext varbinary(200)

declare @cipher varbinary(200)

set @cleartext=convert( varbinary(200),'Test text string')

set @cipher=EncryptByCert(Cert_ID('cert_TestCert'),@cleartext)

select @cipher

--解密失败:因为私钥被删除

select convert(varchar(200),DecryptByCert(Cert_ID('cert_TestCert'),@cipher,N'p@ssw0rd')) as [cleartext]

--***(4) 非对称密钥

--1)使用sn.exe生成非对称密钥,安装vs2005后有sn.exe, 在命令行方式下执行

sn -k g:\asy_Test.key

--2)从文件创建非对称密钥

create asymmetric key asm_Test

from file='g:\asy_Test.key'

encryption by password='p@ssw0rd'

go

select * from sys.asymmetric_keys

--***********示例2 使用加密保护列数据

-----*****(1) 准备工作

--1) 创建示例表

create table empsalary

(EmpID int,

Title nvarchar(50),

Salary varbinary(500)

)

go

--2) 创建数据库主密钥

create master key encryption by password='p@ssw0rd'

go

--3) 创建用于加密的对称密钥

create symmetric key sym_Salary

with algorithm=AES_192

encryption by password='p@ssw0rd'

go

select * from sys.symmetric_keys where [name]='sym_Salary'

------****(2)加密列数据

--1)打开对称密钥

open symmetric key sym_Salary

decryption by password='p@ssw0rd'

go

select * from sys.openkeys

--2)向表中插入数据，并对salary列加密

insert into empsalary values (1,'CEO',EncryptByKey(KEY_GUID('sym_Salary'),'20000'))

insert into empsalary values (2,'Manager',EncryptByKey(KEY_GUID('sym_Salary'),'10000'))

insert into empsalary values (3,'DB Admin',EncryptByKey(KEY_GUID('sym_Salary'),'5000'))

--3)关闭打开的对称密钥

close symmetric key sym_Salary

go

select * from sys.openkeys

--4) 查看表中的数据

select * from empsalary

--(3)解密并访问被加密的数据列

--1)打开对称密钥

open symmetric key sym_Salary decryption by password='p@ssw0rd'

go

--2)使用对称密钥解密并访问被加密的列

select empid,title,cast(DecryptByKey(Salary) as varchar(20)) as salary from empsalary

--3) 关闭对称密钥

close symmetric key sym_Salary

go

--(4)绕过加密数据的攻击

--1)攻击者使用其他数据行的加密数据替换某一行的数据

update empsalary

set salary=(select salary from empsalary where empid=1)

where empid=3

--2)查看被攻击后解密的数据

open symmetric key sym_Salary decryption by password='p@ssw0rd'

select empid,title,cast(DecryptByKey(Salary) as varchar(20)) as salary from empsalary

close symmetric key sym_Salary

--(5)使用验证器防止绕过加密数据的攻击

--1)删除前面添加的数据行

delete empsalary

--2)向表插入数据，并对salary列的数据使用验证器进行加密

open symmetric key sym_Salary decryption by password='p@ssw0rd'

insert into empsalary values (1,'CEO',EncryptByKey(KEY_GUID('sym_Salary'),'20000',1,'1'))

insert into empsalary values (2,'Manager',EncryptByKey(KEY_GUID('sym_Salary'),'10000',1,'2'))

insert into empsalary values (3,'DB Admin',EncryptByKey(KEY_GUID('sym_Salary'),'5000',1,'3'))

--3)解密并访问被加密的数据

select empid,title,cast(DecryptByKey(Salary,1,cast(empid as varchar(3))) as varchar(20)) as salary from empsalary

--4)用同样的方法篡改数据

update empsalary

set salary=(select salary from empsalary where empid=1)

where empid=3

--5)被篡改后的加密了的数据列变成无效

select empid,title,cast(DecryptByKey(Salary,1,cast(empid as varchar(3))) as varchar(20)) as salary from empsalary

--***********示例3 使用数字证书签署存储过程

--*****(1)准备

--1)创建数据库主密钥

create master key encryption by password='p@ssw0rd'

--2)创建签署存储过程所需要的证书

create certificate cert_Product

with subject='Products Sign',

start_date='1/31/2006',

expiry_date='1/31/2008'

go

--3)创建SPDeveloper登录帐户和用户，该用户创建并访问Products表的存储过程

create login [SPDeveloper] with password='p@ssw0rd',default_database=[TestDB]

go

create user [SPDeveloper] for login SPDeveloper with default_schema=[SPDeveloper]

go

create schema products authorization SPDeveloper

go

exec sp_addrolemember @rolename='db_owner',@membername='SPDeveloper'

--4)以SPDeveloper的身份创建存储过程products.usp_Products

execute as user='SPDeveloper'

go

create procedure products.usp_Products

as

select * from dbo.Products

go

revert

select user

--5)创建普通用户jerry

create login [jerry] with password='p@ssw0rd',default_database=[TestDB]

go

create user [jerry] for login jerry

go

--*******(2)使用证书签署存储过程

--1)授予用户jerry执行存储过程的权限

grant execute on products.usp_Products to jerry

--2)以jerry的身份执行存储过程失败，因为拥有权链的断裂的

execute as user='jerry'

select user

go

execute products.usp_Products

go

revert

--3)使用证书在当前数据库创建用户ProductsReader,并为该用户赋予读取products表的权限

create user ProductsReader for certificate cert_Products

go

grant select on products To ProductsReader

--4)使用证书签署当前存储过程

add signature to products.usp_Products by certificate cert_Products

--5)以jerry的身份重新执行存储过程，成功

--因为存储过程将以ProductsReader的权限上下文执行

execute as user='jerry'

select user

go

execute products.usp_Products

go

revert