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SQL Server 2005加密体系(二)
紧接上一篇，再给一段用密钥加密数据的范例，这段代码比较简单，大黄不准像蹂躏大余一样说我灌水！！！

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--创建实验用数据库
USE master
IF EXISTS(SELECT [name] FROM sys.databases WHERE [name] = 'Sales')
 DROP DATABASE Sales
CREATE DATABASE Sales
IF EXISTS(SELECT principal_id FROM sys.server_principals WHERE [name] = 'ryan' AND [type] = 'S')
 DROP LOGIN ryan
CREATE lOGIN ryan WITH PASSWORD = 'P@ssw0rd'
IF EXISTS(SELECT principal_id FROM sys.server_principals WHERE [name] = 'teddy' AND [type] = 'S')
 DROP LOGIN teddy
CREATE lOGIN teddy WITH PASSWORD = 'P@ssw0rd'
GO

--创建用户ryan，并创建数据库主密钥
USE Sales
IF EXISTS(SELECT * FROM sys.database_principals WHERE [name] = 'ryan' AND [type] = 'S')
 DROP User ryan
CREATE USER ryan FOR LOGIN ryan WITH DEFAULT_SCHEMA = dbo
GO
IF EXISTS(SELECT * FROM sys.database_principals WHERE [name] = 'teddy' AND [type] = 'S')
 DROP User teddy
CREATE USER teddy FOR LOGIN teddy WITH DEFAULT_SCHEMA = dbo
GO
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'P@ssw0rd'
GO
--使用服务主密钥加密数据库主密钥，
--在此删除，因为发现数据库主密钥创建时默认及利用服务主密钥加密
--利用服务主密钥加密的数据库主密钥称为自动密钥管理
--可以利用以下查询语句是否启用数据库主密钥的自动密钥管理
SELECT [name], is_master_key_encrypted_by_server FROM sys.databases WHERE [name] = 'Sales'
--以下语句用于启用数据库主密钥的自动管理
--ALTER MASTER KEY ADD ENCRYPTION BY SERVICE MASTER KEY
GO

--为ryan创建证书
IF EXISTS(SELECT [name] FROM sys.certificates WHERE [name] = 'CERT_RYAN')
 DROP CERTIFICATE CERT_RYAN
CREATE CERTIFICATE CERT_RYAN AUTHORIZATION ryan
 --ENCRYPTION BY PASSWORD = 'P@ssw0rd'
   --建议不要使用密码，因为经过测试，是用密码的证书是利用密码保护，
   --而非数据库主密钥，可用以下语句测试证书的加密方法
   --SELECT [name], pvt_key_encryption_type_desc FROM sys.certificates
   --WHERE [name] = 'CERT_DB'
 WITH SUBJECT = 'Certificate For Database',
 START_DATE = '01/01/2006',
 EXPIRY_DATE = '12/31/2015'
GO
--为teddy创建证书
IF EXISTS(SELECT [name] FROM sys.certificates WHERE [name] = 'CERT_TEDDY')
 DROP CERTIFICATE CERT_TEDDY
CREATE CERTIFICATE CERT_TEDDY AUTHORIZATION teddy
 --ENCRYPTION BY PASSWORD = 'P@ssw0rd'
   --建议不要使用密码，因为经过测试，是用密码的证书是利用密码保护，
   --而非数据库主密钥，可用以下语句测试证书的加密方法
   --SELECT [name], pvt_key_encryption_type_desc FROM sys.certificates
   --WHERE [name] = 'CERT_DB'
 WITH SUBJECT = 'Certificate For Database',
 START_DATE = '01/01/2006',
 EXPIRY_DATE = '12/31/2015'
GO

SELECT * FROM sys.certificates

--为ryan和teddy分别创建利用证书保护的对称密码
CREATE SYMMETRIC KEY Key_SYM_RYAN AUTHORIZATION ryan
 WITH ALGORITHM = TRIPLE_DES
 ENCRYPTION BY CERTIFICATE CERT_RYAN
GO
CREATE SYMMETRIC KEY Key_SYM_TEDDY AUTHORIZATION teddy
 WITH ALGORITHM = TRIPLE_DES
 ENCRYPTION BY CERTIFICATE CERT_TEDDY
GO

--创建测试用表
IF EXISTS(SELECT [name] FROM sys.tables WHERE [name] = 'encryption')
 DROP TABLE encryption
CREATE TABLE dbo.encryption
(
 PT nchar(10),       --Plain Text
 ET varbinary(128),  --Encrypted Text
)
GO
GRANT SELECT, INSERT ON encryption TO ryan
GRANT SELECT, INSERT ON encryption TO teddy

--完成准备工作，开始测试加密
EXECUTE AS LOGIN = 'ryan'
OPEN SYMMETRIC KEY Key_SYM_RYAN DECRYPTION BY CERTIFICATE CERT_RYAN
INSERT INTO encryption
 VALUES (N'RYAN',EncryptByKey(Key_GUID('Key_SYM_RYAN'), N'RYAN'))
CLOSE ALL SYMMETRIC KEYS
REVERT

EXECUTE AS LOGIN = 'teddy'
OPEN SYMMETRIC KEY Key_SYM_TEDDY DECRYPTION BY CERTIFICATE CERT_TEDDY
INSERT INTO encryption
 VALUES (N'TEDDY',EncryptByKey(Key_GUID('Key_SYM_TEDDY'), N'TEDDY'))
CLOSE ALL SYMMETRIC KEYS
REVERT

--测试数据已经被加密
SELECT * FROM encryption

--解密数据
EXECUTE AS LOGIN = 'ryan'
OPEN SYMMETRIC KEY Key_SYM_RYAN DECRYPTION BY CERTIFICATE CERT_RYAN
SELECT PT, CONVERT(nchar,DecryptByKey(ET)) AS ET FROM encryption
CLOSE ALL SYMMETRIC KEYS
REVERT
EXECUTE AS LOGIN = 'teddy'
OPEN SYMMETRIC KEY Key_SYM_TEDDY DECRYPTION BY CERTIFICATE CERT_TEDDY
SELECT PT, CONVERT(nchar,DecryptByKey(ET)) AS ET FROM encryption
CLOSE ALL SYMMETRIC KEYS
REVERT

转自
http://blog.csdn.net/softj/archive/2006/05/11/723436.aspx