Genuine need to hack.

Hi, 

SQL 2012

I have been tasked with re-writing a password store from classic ASP/VB (CodeCharge 4) into ASP.net/C#.  The company has "lost" the source code but I do have access to the IIS root so can see some of it. 

The password column in the database is encrypted using a symmetric key and at the point of encryption this command is issued: 

OPEN SYMMETRIC KEY akey  DECRYPTION BY CERTIFICATE acert;

I don't want to make matters worse by breaking the key so I backed up/restored to a different server.  As I have both the key and cert will I be able to decrypt the column values.  When I run this on my test server I get an error about a db master key, is it just a case of creating one of those. 

Thanks in advance.