EccKey

A P-256 key pair, in the shape PlayReady stores them.

A device's group, signing and encryption keys are all of this form. On disk they appear as zgpriv.dat, zprivsig.dat and zprivencr.dat, and inside a .prd as fixed 96-byte slots.

The public point is always derived from the private scalar rather than read from the blob, so a .prd whose stored public half disagrees with its private half cannot produce a key pair that fails silently later.