How to store a 256 bit key in /sys/fsl_otp/HW_OCOTP_HDCP_KEY*

[DavisRoman]

Hello,

Our product currently uses a i.mx6solo and I have been asked to store a 256 bit key in the i.mx6 fuses.

In userspace, i see that there is an interface for accessing these fuses via /sys/fsl_otp,

More important, I see that there are a bunch of fields ( HW_OCOTP_HDCP_KEY* ) available.

I was reading about these fuses in the reference manual and they seems to be related to digital rights management.

Since we’re not using this feature in our product, my belief is that we should be able to store our key in these fuses.

( Even if we have to split up this 256 bit key into multiple fields would be ok too )

However, if I echo a value into one of these fuses, the value doesn't persist across reboot.

In fact, I'm not able to cat any of the values from any fuses. (Perhaps this occurs because I'm performing an illegal write, I'm not sure.)

Any suggestions?

P.S. burning the fuses via u-boot or the freescale manufacturing tool is not an option. It would have to be via the userspace /sys/fsl_otp interface.

Thanks,

Davis

[Yuri]

  As for HDCP and DTCP keys  -  generally special fuses are reserved for it. By default, the HDCP feature

in the i.MX6 HDMI transceiver is disabled and the fuses are not visible / available (however, the HDMI interface

still can be used without this) . This feature must be separately configured and requires a separate HDCP license.

Please contact your local Freescale FAE/representative for more information on HDCP.

Have a great day,
Yuri

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