From what I remember from my past research on the Magicgate KELF mechanism, there are a two keys to decrypt two main parts of the KELF: The content key (Kc) and the bit table (Kbit). Each KELF has both keys.
Originally Posted by mark_k
The bit table describes the various protected and unprotected sections of the KELF, while I think that the content key is for decrypting the encrypted parts of the KELF. Both keys are obtainable by software means.
The MCID is an unique ID that belongs to each Memory Card. If this ID cannot be retrieved for whatever reason, it will not be a bootable Memory Card the KELF cannot be decrypted.
I suppose that full support for Magicgate by the Memory Card adaptor is required, as operations like retrieving the Memory Card's ID (MCID) and certain (emulated) MECHACON challenges that are used to generate some other keys require a working Magicgate implementation.
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit