Service A provides a customized report generating capability. Due to infrastructure limitations, the number of service consumers permitted to access Service A concurrently is strictly controlled. Service A validates request messages based on the supplied credentials (1). If the authentication of the request message is successful, Service A sends a message to Service B (2) to retrieve the required data from Database A (3). Service A stores the response from Service B (4) in memory and then issues a request message to Service C (5). Service C retrieves a different set of data from Database A (6) and sends the result back to Service A (7). Service A consolidates the data received from Services B and C and sends the generated report in the response message to the service consumer (8).

It has been discovered that attackers have been gaining access to confidential data exchanged between Service A and Service B, and between Service A and its service consumers. What changes can be made to this service composition architecture in order to counter this threat?

• A. Apply the Direct Authentication pattern in order to protect message exchanges between Service A and its service consumers and between Service A and Service B.
  This approach will establish a password-based authentication mechanism that relies on a local identity store and will therefore prevent access by attackers.
• B. None of the above
• C. Apply the Service Perimeter Guard pattern in order to protect message exchanges between Service A and its service consumers. Apply the Direct Authentication pattern in order to protect message exchanges between Service A and Service B.
• D. Apply the Data Origin Authentication pattern to protect the final report sent by Service A to its service consumer. Service A can generate a message digest of the final report, after which it can sign the digest with its own private key. It then can send both the final report and the signed message digest to its service consumer. This service consumer can generate its own message digest, decrypt the signed digest using the public key of Service A (which proves that Service A sent the message), and then compare the two digests. If the digests match, it guarantees that the final report was not tampered with during transmission.

• A.
• B. Apply the Data Origin Authentication pattern together with the Data Confidentiality pattern in order to establish message-layer security that guarantees the confidentiality and integrity of messages exchanged by Service Consumer A and Service A.
  Further, a security policy can be created to require that security credentials submitted to Service A must be digitally signed and encrypted and also contain a timestamp to validate the actual time the request was issued. Industry standards that can be used for this solution are WS- Policy, WS-SecurityPolicy, XML-Encryption, and XML-Signature.
• C. Apply the Service Perimeter Guard pattern to establish a perimeter service that can perform security functions on behalf of Service A.
  Next, apply the Data Confidentiality pattern so that the security credential information provided by Service Consumer A with the request message is encrypted with the secret key shared between the perimeter service and Service Consumer A.
  The perimeter service evaluates the credentials and if successfully authenticated, forwards the request message to Service A.
  Transport-layer security is used to protect message exchanges between Service A and Service Consumer
• D. Apply the Trusted Subsystem pattern together with the Data Origin Authentication pattern in order to establish a utility service that performs the security processing on behalf of Service A.
  Service Consumer A must digitally sign all request messages and encrypt the credential information using the public key of the utility service. The utility service can then verify the security credentials and the digital signature to establish the validity of the request message. If the request message is permitted, the utility service establishes a composite trust domain that encompasses Service Consumer A, Service A, Database A, and the legacy system. Because all communications remain within a single trust domain, malicious intermediaries will not be able to gain access to any exchanged data.
• E. Apply the Service Perimeter Guard pattern together with the Trusted Subsystem pattern to establish a perimeter service that can perform security functions on behalf of Service A.
  The utility service can verify the validity of the request messages from Service Consumer A by authenticating the request message against an identity store. If the request message is authenticated, the utility service then sends it to Service A for further processing. All communications between Service A and Service Consumer A can be encrypted using the public key of the intended recipient, and signed using the private key of the sender.
  Industry standards that can be used for this solution are XML-Encryption, XML-Signature, and WS-Trust.