How to encrypt and decrypt integer data type column in SQL Server using symmetric key

Question

I can encrypt and decrypt varchar, nvarchar,char columns using symmetric key but cannot do the same on int,datetime,float,bigint data types columns

Sample table: Mytable

| Id  Code  percentage  name    activity   |  
+------------------------------------------+
| 1   ad     43.43    James    Running     |  
| 3   Pr     70.43    Sam      Cooking     |  
| 5   nt     90.34    Lisa     Walking     |  
| 4   ash    0.00     James    Stealing    |  
| 2   han    0.00     James    Lacking     |  
| 8   ant    73       Sam      Cooking     |

I want to encrypt and decrypt ID column and Percentage which are of integer and float data types respectively.

I am using this code to encrypt:

OPEN SYMMETRIC KEY SymKey DECRYPTION BY CERTIFICATE data  

ALTER TABLE Mytable 
SET ADD idencry VARBINARY(128) NULL  


UPDATE Mytable 
SET idencry = ENCRYPTBYKEY(KEY_GUID('datamSymKey'), CONVERT(varbinary, ID))

To decrypt I am using this code:

SELECT 
    id,
    CONVERT(NVARCHAR(60), DECRYPTBYKEY(idencry )), * 
FROM 
    Mytable

But its not returning the correct result... same goes with float and datetime date type

Answer 1

Hi i have tested thoses code on SQL Server 2016 and it's work :

CREATE CERTIFICATE Test04   
   ENCRYPTION BY PASSWORD = 'pGFD4bb925DGvbd2439587y'  
   WITH SUBJECT = 'Sammamish Shipping Records',   
   EXPIRY_DATE = '20201031';  
GO  

CREATE SYMMETRIC KEY #SymKey   
WITH ALGORITHM = AES_128 
ENCRYPTION BY CERTIFICATE Test04;  
GO  

create Table #TestData
(
    Id int,
    Code varchar(10)
)

Insert into #TestData
(
    Id,
    Code
)
SELECT 1,'AA'
UNION 
SELECT 2,'BB'
UNION 
SELECT 3,'CC'
UNION 
SELECT 4,'DD'
UNION 
SELECT 5,'EE'
UNION 
SELECT 6,'FF'

SELECT * FROM #TestData

OPEN SYMMETRIC KEY #SymKey DECRYPTION BY CERTIFICATE Test04 WITH PASSWORD='pGFD4bb925DGvbd2439587y'

ALTER TABLE #TestData 
 ADD idencry VARBINARY(128) NULL  


UPDATE #TestData 
SET idencry = ENCRYPTBYKEY(KEY_GUID('#SymKey'), CONVERT(varbinary, Id))



SELECT * FROM #TestData


OPEN SYMMETRIC KEY #SymKey DECRYPTION BY CERTIFICATE Test04 WITH PASSWORD='pGFD4bb925DGvbd2439587y'

SELECT 
    Id,
    CONVERT(int, DECRYPTBYKEY(idencry)) AS 'IdDecrypted', * 
FROM 
    #TestData


DROP TABLE  #TestData 

DROP SYMMETRIC KEY #SymKey   

DROP CERTIFICATE Test04

I think you have to CAST to the source type when you using decryptbykey

 CONVERT(NVARCHAR(60), DECRYPTBYKEY(idencry )), * 

What is your "Id" column type ?

Can you try :

CONVERT(INT, DECRYPTBYKEY(idencry )), *