IOCTL_AACS_SEND_CHALLENGE_KEY control code
Sends the host's challenge key to the logical unit. The host's challenge key consists of a point on an elliptic curve and its associated signature.
The buffer at Irp->AssociatedIrp.SystemBuffer contains a AACS_SEND_CHALLENGE_KEY structure.
The Information field is set to the number of bytes transferred. The Status field is set to STATUS_SUCCESS or possibly STATUS_INSUFFICIENT_RESOURCES.
The IOCTL_AACS_SEND_CHALLENGE_KEY request corresponds to the step in the Advanced Access Content System (AACS) authentication algorithm (AACS-Auth) in which the host provides the drive a point on the curve. For a complete description of AACS-Auth, see the Advanced Access Content System, Introduction and Common Cryptographic Elements specification that is published by Advanced Access Content System Licensing Administrator (AACS LA).