1. Andrew J. Hewatt, Gayatri Swamynathan and Michael T. Wen Department of Computer Science, UC-Santa Barbara A Case Study of the WS-Security Framework

2. 06.03.2005 2  Security in the web services industry is of great importance and a deciding factor for many corporations when moving to a web services software architecture.  The WS-Framework was created by a collection of industry leaders to be the solution to this.  Our case study focuses on the security of the WS-Framework and its extensions to determine if they are indeed adequate. Why talk about security? Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

3. 06.03.2005 3  The Framework and it’s extensions were meant to enable two parties to securely communicate via SOAP messaging.  There are currently six extensions that reside on top of WS-Security and SOAP. Two of these have been defined but are not yet published.  We chose to focus on the WS-Security, WS-Trust, WS-Policy and WS-Secure Conversation modules. These we feel encompass most of the security areas within our scenario. WS-Framework Defined Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

4. 06.03.2005 4 WS-Framework Overview Soap Foundation XML Encryption XML Digital Signature Security Extensions WS-Security XKMSSAMLXACMLSPML WS-PolicyWS-TrustWS-Privacy WS- Secure Conversation WS- Federation WS- Authorization Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

5. 06.03.2005 5  A single client will send a request with a loan amount and time period to a loan bidding website.  The website will then iterate this query to all selected banks who will then formulate a response.  The website will gather all responses and display the corresponding interest rates to the user. Defining The Scenario Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

6. 06.03.2005 6 Module Interactions Client Loan Website Bank ABank ZBank Y Loan Services Commodity Trading Risk Management Partner Interface NYSE Trading Services Partner B Partner A Partner C Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

7. 06.03.2005 7 Security Interactions Client Loan Website Bank ABank ZBank Y Loan Services Commodity Trading Risk Management Security Module Partner Interface NYSE Trading Services Partner B Partner A Partner C Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

8. 06.03.2005 8  Identity Management: Each entity must be able to identity itself to the party it wants to communicate with  Policy Management: Each entity enforces policies with other entities. E.g. message format, who has access to what, what one needs to process.  Secure Messaging: authentication, confidentiality, integrity, non-repudiation Security Requirements Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

9. 06.03.2005 9  Goal: provide message-level security which addresses confidentiality, integrity, and single message authentication.  Non-Goals:  Establishing a security context that requires multiple exchanges  Key exchange and derived keys  How trust is established or determined  Two main parts – encrypted message and signature. WS-Security Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

10. 06.03.2005 10 ID=“MyToken” … … … Security Message Key used for the signature Key used to encrypt message Contains signature algorithm, key info, and signature value Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Trust WS-Policy WS-Secure Conversation Conclusions

11. 06.03.2005 11  WS-Security alone is not enough to address the security issues  Scenario: An eavesdropper is listening to the traffic of messages between two parties. After a while he or she may be able to crack the symmetric key and hijack the traffic.  Solution: This is handled by WS- SecureConversation. A Bad Example Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Trust WS-Policy WS-Secure Conversation Conclusions

12. 06.03.2005 12  A policy is comprised of a collection of policy alternatives.  Each policy alternative is a collection of policy assertions that represent an individual requirement, capability of other property of a behavior.  Example: Assertions “exactlyOne” Kerberosv5TGT or X509v3  Policy intersection (involves domain-specific processing!)  Assertions should be digitally signed. WS-Policy Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

13. 06.03.2005 13  Enables the issuance and dissemination of credentials within different trust domains  If a message arrives without having the required proof of claims, the service should ignore or reject the message. WS-Trust Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions Loan Website Bank A

14. 06.03.2005 14  Token issuance  Token renewal  Token cancellation  Token validation Security Token Service Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions Loan Website 1. Loan Request 2. wst:RequestSecurityToken 3. wst:RequestSecurityTokenResponse with embedded challenge 4. wst:RequestSecurityTokenResponse with answer to the challenge 5. wst:RequestSecurityTokenResponse with issued security token Bank A

15. 06.03.2005 15  The WS-SecureConversation extension defines two main additions, namely a security context and derived keys.  Establishing a security context is more beneficial for a series of messages between two parties because it is shared for the lifetime of the conversation.  Derived keys allows the involved parties to keep security fresh during interaction instead of relying on just one secret.  Possible need for further extensions… WS-SecureConversation Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions

16. 06.03.2005 16  WS-Framework is adequate for our scenario but may be too flexible.  We feel the WS-Security framework should be more rigid by enforcing further rules that will govern which parts of each extension are to be used with one another.  WS-Security framework satisfies Identity Management, Policy Management, and Secure Messaging but may need extra extensions. Conclusions Introduction WS-Framework Loan Bidding Scenario Security Requirements WS-Security WS-Policy WS-Trust WS-Secure Conversation Conclusions