Windows C User Exits › Windows Client Middleware User Exits › Communications Bridge - Windows User Exits › DECRYPT—Cooperative Flow Decryption Exit (Windows) › Purpose

Purpose

The CFB data transmitted from a DPC application can optionally be encrypted. A flag byte in the CFB header notifies the receiver of the CFB that the CFB has been encrypted. It is the receiver's responsibility to decrypt the CFB prior to using it.

With respect to the Comm. Bridge, the data in the CFB will only need to be decrypted if the security data located in the security offset section is to be used when sending the cooperative flow request to a target server. The Comm. Bridge uses the CMUseSecure CFB flag to determine if the data in the security offset should be used.

The CMUseSecure flag is set by the client runtime if its invocation of the client side security exit returns a TRUE for the bClntMgrSecurity flag. Therefore, the following considerations must be met before the Comm. Bridge invokes its decryption user exit:

1. The CFB's CMUseSecure flag is set, indicating that the requesting client requires the Comm. Bridge use the security data it placed into the security offset section when handling the cooperative flow.
2. The CFB encryption flag byte indicates that it has been encrypted.

If the preceding conditions are met, the Comm. Bridge must invoke its decryption user exit.