可以查看：
OPEN SYMMETRIC KEY 命令关于 对称密钥加密使用证书解密
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password'
go
CREATE CERTIFICATE CertTest
with SUBJECT = 'Test Certificate'
GO
--创建非对称密钥
CREATE ASYMMETRIC KEY TestAsymmetric
WITH ALGORITHM = RSA_2048
ENCRYPTION BY PASSWORD = 'password1' ;
GO
ALTER ASYMMETRIC KEY TestAsymmetric WITH PRIVATE KEY (DECRYPTION BY PASSWORD = 'password1')
--DROP ASYMMETRIC KEY TestAsymmetric
--创建对称密钥
CREATE SYMMETRIC KEY TestSymmetric
WITH ALGORITHM = AES_256
ENCRYPTION BY PASSWORD = 'password' ;
GO
OPEN SYMMETRIC KEY TestSymmetric
DECRYPTION BY PASSWORD = 'password' ;
go
SELECT
ENCRYPTBYASYMKEY(ASYMKEY_ID ('TestAsymmetric'), name) ,
CAST(deCRYPTBYASYMKEY (ASYMKEY_ID( 'TestAsymmetric'),ENCRYPTBYASYMKEY (ASYMKEY_ID( 'TestAsymmetric'),name ) )
as nvarchar(200 )),
ENCRYPTBYCERT ( Cert_ID('CertTest' ),name),
CAST(deCRYPTBYCERT (Cert_ID ('CertTest'), ENCRYPTBYCERT (Cert_ID( 'CertTest'),name ))
as nvarchar (200)),
EncryptByKey ( KEY_GUID('TestSymmetric' ),name),
CAST(decryptByKey (EncryptByKey (KEY_GUID ('TestSymmetric'), name))
as nvarchar (200))
FROM sys .objects
