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Configure decryption methods to protect message confidentiality using the WSS APIs

We can configure decryption method information for the response consumer (client side) section of the binding file. Decryption information is used to specify how the consumers (receivers) decrypt incoming SOAP messages. To configure decryption, specify which message parts to decrypt and specify which algorithm methods and security tokens are to be used for decryption.

Confidentiality refers to encryption while integrity refers to digital signing. Confidentiality reduces the risk of someone understanding the message flowing across the Internet. With confidentiality specifications, the message is encrypted before it is sent and decrypted when it is received at the correct target. Prior to configuring decryption, familiarize yourself with XML encryption.

For decryption, specify the following:

To configure decryption and decrypted parts on the client side, use the WSSDecryption and WSSDecryptPart APIs, or configure policy sets using the console.

WebSphere Application Server provides default values for bindings. However, an administrator must modify the defaults for a production environment.

WAS uses decryption information for the default consumer to decrypt parts of the SOAP message. The WSSDecryption API configures the following required parts as decrypted parts.

decrypted parts. Use the decryption information to specify
Decryption parts Description
Keywords Keywords are used to add the decrypted parts to the SOAP message.
XPath expression XPath expressions are used to add the decrypted parts to the SOAP message.
WSSDencryptPart object This object adds the decrypted parts to the SOAP message.
WSSVerification object This object adds the signature verification component as a decrypted part.
Header This part adds the header in the SOAP header, specified by QName, as a decrypted part.
Security token object This object adds the security token as a decrypted part.

Web Services Security API (WSS API) supports symmetric encryption, by using a shared key, only when Web Services Secure Conversation (WS-SecureConversation) is used.

The WSS APIs allow the use of either keywords or an XPath expression to specify the parts of the SOAP message that are to be decrypted. WebSphere Application Server supports the use of the following keywords:

Keyword References
BODY_CONTENT The keyword for the body contents of the SOAP message body as a decryption target.
SIGNATURE The keyword for the signature element as a decryption target.
USERNAME_TOKEN, The keyword for the Username token element as a decryption target.

If configuring using the WSS APIs, the WSSDecryption and WSSDecryptPart APIs complete these high-level steps:

  1. Use the WSSDecryption API to configure encryption. The WSSDecryption API performs these tasks by default:

    1. Generates the callback handler.

    2. Generates the consumer security token object.

    3. Add the security token reference type.

    4. Add the WSSEncryptPart object.

    5. Add the parts to be encrypted. Adds the default parts for decryption by using keywords and XPath expressions.

    6. Add the verification component.

    7. Add the header in the SOAP message, specified by QName.

    8. Sets the default data encryption method.

    9. Whether the key is to be decrypted using a Boolean value. Calls this method when the shared key is encrypted.

    10. Sets the default key encryption method.

  2. Use the WSSEncryptPart API to configure encrypted parts or add a transform method. The WSSEncryptPart API performs these tasks by default:

    1. Sets the encrypted parts specified by using keywords or an XPath expression.

    2. Sets the encrypted parts specified by an XPath expression.

    3. Sets the signature component object, WSSSignature.

    4. Sets the header in the SOAP message, specified by QName.

    5. Sets the generator security token.

    6. Add the transform method, if needed.

  3. Change from the default values for algorithm or message parts, as needed. For example: you could change one or more of the following items:

    • Add USERNAME_TOKEN as a target of decryption.

    • Change the data encryption algorithm from the default value of AES 128.

    • Change the key encryption algorithm from the default value of KW_RSA_OAEP.

    • Specify to not encrypt the encryption key (false).

    • Change the security token type from the default value of X.509 token.

    • Only use BODY_CONTENT as an encryption part and not use SIGNATURE also.


Results

The decryption information is configured for the consumer binding.


Example

The following is an example of the WSSDecryption API: 

WSSFactory factory = WSSFactory.getInstance();
WSSConsumingContext concont = factory.newWSSConsumingContext();
    X509ConsumeCallbackHandler callbackhandler = generateCallbackHandler();
// see X509ConsumeCallbackHandler
    WSSDecryption dec = factory.newWSSDecryption(X509Token.class, 
        callbackhandler);
    
 concont.add(dec);


What to do next

We must configure similar encryption information for the client-side request generator (sender) bindings, if we have not already configured the information.

Next, review the WSSDecryption API process.


Subtopics


Related concepts

  • XML encryption


    Related tasks

  • Signing and encrypting message parts using policy sets
  • Configure encryption to protect message confidentiality using the WSS APIs