Encrypting SQL Server Data with Certificate and Symmetric Key - sql

Question

I am trying to encrypt database columns using a certificate and a symmetric key.
I successfully created the certificate and symmetric key using the following:
CREATE CERTIFICATE MyCertificate
ENCRYPTION BY PASSWORD = 'password'
WITH SUBJECT = 'Public Access Data'
GO
CREATE SYMMETRIC KEY MySSNKey
WITH ALGORITHM = AES_256
ENCRYPTION BY CERTIFICATE MyCertificate
I tried encrypting and decrypting some data using the following:
DECLARE #Text VARCHAR(100)
SET #Text = 'Some Text'
DECLARE #EncryptedText VARBINARY(128)
-- Open the symmetric key with which to encrypt the data.
OPEN SYMMETRIC KEY MySSNKey
DECRYPTION BY CERTIFICATE MyCertificate;
SELECT #EncryptedText = EncryptByKey(Key_GUID('MySSNKey'), #Text)
SELECT CONVERT(VARCHAR(100), DecryptByKey(#EncryptedText)) AS DecryptedText
When I do so, I get the following error message:
The certificate has a private key that is protected by a user defined
password. That password needs to be provided to enable the use of the
private key.
Ultimately, what I am trying to do is write a stored procedure that will take some unencrypted data as input, encrypt it, then store it as encrypted varbinary. Then I'd like to write a 2nd stored procedure that will do the opposite - i.e., decrypt the encrypted varbinary and convert it back to a human-readable data type. I would rather not have to specify the password directly in the stored procedure. Is there any way to do that? What am I doing wrong in my code above?
Thanks.

Answer 1

You just need to use:
OPEN SYMMETRIC KEY MySSNKey
DECRYPTION BY CERTIFICATE MyCertificate WITH PASSWORD = 'password';

Answer 2

You nead use MASTER KEY
Example:
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'MasterPassword';
CREATE CERTIFICATE MyCertificate WITH SUBJECT = 'Public Access Data';
CREATE SYMMETRIC KEY MySSNKey WITH ALGORITHM = AES_256 ENCRYPTION BY CERTIFICATE MyCertificate;
OPEN SYMMETRIC KEY MySSNKey DECRYPTION BY CERTIFICATE MyCertificate;
SELECT Customer_id, Credit_card_number_encrypt AS 'Encrypted Credit Card Number',
CONVERT(varchar, DecryptByKey(Credit_card_number_encrypt)) AS 'Decrypted Credit Card Number'
FROM dbo.Customer_data;
CLOSE SYMMETRIC KEY MySSNKey ;