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
