Fetch an Opaque Object from device.
Retrieve an Opaque Object (like an X.509 certificate) from the device.
Fetch Opaque Object 0xe255 and store in the file cert.der:
0xe255
cert.der
yubihsm> get opaque 0 0xe255 cert.der
Tc = 0x43
Lc = 2
Vc = I
I := Object ID (2 bytes)
Tr = 0xc3
Lr = LD
Vr = D
D := Data