1. Building Defense in Depth using the Full Spectrum of SQL Server Encryption
Michael Keleher
Database Administrator
Hays Consultant at PwC

2. Presented by Mike Keleher
20 years of software development experience
7 years DBA experience
MIS Degree from University of South Florida

3. "Cybersecurity must mean more than protecting the system -- it must also include protecting data," said John Cohen, former acting undersecretary for intelligence and analysis at DHS. "If information contained within government and private-sector systems is encrypted, then the harm caused by cyberattacks such as this one would be minimal."
Security experts: OPM breach shows Einstein isn't enough
FCW.com
Article dated 6/15/2015

4. Topics Encryption terminology Column level encryption Code encryption
SQL Server connection encryption
Transparent Data encryption
Reporting Services encryption
TLS and SSL
Problems and solutions
SQL Server 2016 Always Encrypted

5. Keys A value supplied to an algorithm to encrypt or decrypt data
Symmetric keys
Uses only one key to both encrypt and decrypt data
Asymmetric keys
Uses a pair of mathematically related keys named private key\public key
One key can decrypt what the other key encrypts

6. Algorithms
A mathematical function used with a key to encrypt or decrypt a message
AES (widely endorsed as the most secure selection)
Triple DES
RSA
BLOWFISH

7. Hash function
A hash function takes in data and returns back a fixed length block of bits such that any change to the data should result in a different block.

8. Certificates
A package that contains a user's Public Key, which has been signed and encrypted using the private key of a well- known Certificate Authority and based on the x standard. 
Enables SSL

9. Certificate Authority
Certificate Authority is the issuer of the certificate. It is denoted in the “Issued by” section of the certificate and can be based on one of the following
Self signed
Domain certificate
Public CA certificate

10. Certificate Trust and trust chains
There are two types of certificate authorities (CAs), root CAs and intermediate CAs
To facilitate this process of verifying a chain of trust, every certificate includes the fields «Issued To» and «Issued By»
Certificate validation commonly called “Walking the certificate chain”

11. Key protection hierarchy
Based on ANSI X9.17

12. Key scheme in SQL Server
1. Service Master Key
Symmetric key in the master database encrypted by the Windows Data Protection API. Used to encrypt linked server connection information, credentials and proxy accounts.
2. Database Master Key
Symmetric key created within a database and encrypted by password supplied during creation using AES_256 algorithm for and above, triple DES for earlier versions
3. Asymmetric keys and Certificates
Use public\private key pairs. Certificates generated within SQL are all self signed. Private key encrypted by password or Database Master Key.
4. Symmetric keys
Can be encrypted by password, certificate, asymmetric key, another symmetric key, or Extensible Key Management provider. Can’t be protected directly by the DMK.

13. Service master Key
Created automatically by SQL Server the first time there is a need for it
Can only be opened by the service account
Regenerating or restoring is resource intensive
Protects linked server logins and credentials
Not accessible by the server if you restore master database to a different system and change service accounts

14. Database master key Encrypted by Service Master Key using AES 256
Two copies exist. One in the user database and one in the master

15. Asymmetric key
Can be encrypted by password, certificate or symmetric key
Can be created from a file
Cannot be backed up separately from the database
It is possible to use ALTER to remove the private key so the Asymmetric key can only be used to encrypt and not decrypt

16. Certificates
By default, certificate private key is encrypted by Database Master Key
Can be altered to remove private key
Certificate and private key backed up to separate files
Every Certificate in SQL Server is a self signed certificate that adheres to the x.509 standard
Can be used to encrypt data

17. Symmetric key No backup No private key removal
Can be reproduced on different servers from script
SQL Server will allow changes to methods for encrypting the key, but will never allow the key to be unencrypted on the server

18. Certificate Encryption Example

19. Certificate Encryption Example

20. Extensible Key Management
Provides an interface for Hardware Security Modules to perform cryptography
Introduced in 2008
Only available in … Enterprise Edition

21. Encryption System tables

22. Example Encryption function
Each key has a key guid that must be used
Encryption and decryption functions can have authenticators

23. Authenticators Helps deter whole value substitution
Integrated into the encrypted column and required to decrypt

24. Column Encryption Encrypted data must be stored in Varbinary column
Remains encrypted in memory and in storage

25. Anatomy of an encrypted column
Symmetric key cipher text message format

26. Indexing encrypted columns
Encryption functions on server are non-deterministic, therefore the output is not repeatable

27. Indexing that won’t work
EncryptByKey returns different values for the same message

28. Resolving the indexing problem
Be careful. If a workaround is implemented incorrectly it could compromise the encrypted data
Hashing the message makes it output predictable and can lead to a dictionary attack

29. Replicating Encrypted Columns
Transfer data without decrypting
Data is encrypted on publisher, in transit and at subscriber and only decrypted when used.
Same symmetric or asymmetric key must be created on both databases

30. Permissions needed to decrypt
Grant REFERENCES on symmetric keys
Grant CONTROL to those who will manage these objects
Anyone with CONTROL can run BACKUP CERTIFICATE
CONTROL permission on a certificate is required to use it for decryption either directly or indirectly
Warning: The db_owner role, db_securityadmin and the db_ddladmin role have CONTROL permissions on certificates and the db_backupoperator role can back up the database.

31. Procedure Code signing with Certificates
Can generally be used to solve some granular permission issues
There are five steps of module signing:
Create a signing certificate
Sign the module using the signing certificate
Create a certificate user and map to the certificate
Grant the permissions to the certificate user
Grant permission to the module for the users/groups

32. Code signing example Create a signing certificate
Sign the module using the signing certificate
Create a certificate user and map to the certificate
Grant the permissions to the certificate user
Grant permission to the module for the users/groups

33. Results

34. Code signing concept
It’s like telling the user “You don’t have permissions to operate the motor, but you do have permission to knock over the first domino”

35. Where is my encryption?
using System views to find encryption artifacts

36. Stored procedure encryption
Only available in SQL Server 2005 and above
Converts text of procedures to obfuscated form, even in system tables
Encrypted procedures can’t be replicated
Text still available to administrators using the Dedicated Administrative Connection
Can be used with functions, procedures and triggers

37. Connection encryption
Install Certificate on Server
Configure server to use Certificate and force connection encryption using SQL Server Configuration Manager

38. SQL Server Connection Encryption Certificate Configuration
Certificate must be created for Server Authentication
Highly recommend Domain or public CA
SQL Server will only use certificates from the Computer certificate store for Windows
Assigning permissions on the private key to the Virtual Service account using the Manage Private Keys option for the SQL Server service is highly recommended

39. Man in the middle Attack
Possible when using self-signed certificates or certificate obtained using identity theft

40. Potential issues with Connection Encryption
Java VMs handle their own connection encryption
Replication agents can be affected
Set trust server certificate to yes and use the encryptionlevel option for the distributor

41. Transparent Data Encryption
Encrypts Data files and log files
Only available in ... Enterprise Edition, however, backup encryption is available on all versions of SQL Server starting in 2014
To implement, create a Database Master Key and Certificate in the master database, then create a Database Encryption Key in the user database and set the user database encryption property to ON.

42. Backup Encryption
Available in all versions of SQL Server starting in 2014

43. Reporting Services Encryption
If you have any instances of Reporting Services, then the encryption keys and password needs to be backed up

44. TLS and SSL How channel encryption is negotiated between systems
Determine the highest level protocol mutually supported by the client and the server.
The currently recognized protocols are, from highest to lowest: TLS1.2,TLS1.1, TLS1.0, SSL3.0, SSL2.0 

45. How to cause Trouble...
and recover from it

46. Changing systems and service accounts in one move
Changing systems and service accounts during a restore of master, msdb and user databases will cause the Service Master Key to be inaccessible
What you will lose if you can't recover:
a. Encrypted backups
b. TDE Encrypted files
c. Encrypted Column data
d. Linked Server Logins
e. Credentials

47. Service Master Key recovery
If your system reports a problem…
There is a way to recover…
2012 and earlier
2014 and later use SSCM
Warning: Do not regenerate the Service Master Key Until you have recovered it first

48. Only taking backups of databases without backups of keys and certificates
Inhibits recovering user database to other servers
Solutions
restore problematic user databases from a good backup to same server under a different name
Build a new server, restore master, msdb and user databases and it's imperative to use the same service account and password
Warning: If you don’t backup either the master database or the Service Master Key you could lose it all

49. Changing the service account outside of the SQL Server Configuration Manager
SQL Server will re-encrypt the Service Master Key when the account information is changed using SQL Server Configuration Manger.
Do not use Computer Manager or other command line options as they are not aware of the encryption requirements
Back up the Service Master Key
Warning: If you change the password for the service account outside of SQL Server Configuration Manager and the server crashes before it can be restarted, you could lose access to the Service Master Key

50. A Practical Example of Solving Encryption Problems
The Scenario
A SQL Server instance implemented by a group outside of IT had their instance crash
Unrecoverable system board error occurred
You are a Database Administrator assigned to rebuilding the instance and provided with the following facts
One of their team members decided to encrypt a substantial number of columns in a mission critical database
The person who set up the instance had a backup job that ran every day. It deleted the previous days backups and created a current backup set.
They have the domain user and password used as the service account
However, they only backed up the user databases and not the master database.

51. More Details about the situation
When you inquire about how the encryption was implemented, you are sent a hyperlink to an StackOverflow blog page and were told that they copied the script from this page, changed the values and ran it.
... no one saved the script
He did mention that he changed all of the parameters, but forgot to change the Key_Source

52. Documentation for symmetric key

53. The Solution
We can solve this by applying knowledge of the key Hierarchy, system tables and format of the encrypted data
Facts we know
We have a backup of the user database
We know the script that was used to create the keys
We also know that they Key_Source is used to create the symmetric key
We know that the symmetric key was encrypted by the certificate
We know the format of the encrypted column

54. Decryption attempt

55. If you only had the password for the database master key
… but you don’t in this situation

56. The scripted solution

57. One last item before we can decrypt

58. SQL Server 2016 Always Encrypted

59. Back up Keys and certificates
Back up all Database Master Keys, Service Master Keys and Certificates
Symmetric and Asymmetric keys are backed up with the database, however, if you want to share a symmetric key among several systems it can be created from a file or using the algorithm, key_source and identity_value parameters
If you have any column encryption, it is important to back up the Database Master Key and keep the password used to encrypt it safe and accessible

60. Reference material Raul Garcia’s Blog Channel 9 Always Encrypted Video
Indexing Encrypted Columns
Encrypted Message Description
Channel 9 Always Encrypted Video
Technet SQL Server Encryption
MSDN SQL Server Encryption
X.509 Certificate Format and Validation
How to Crack the Symmetric Keys in the Database Wide Open

61. Contact Information
LinkedIn: Michael Keleher

62. Thank you for attending