i.Mx8MP Fast Auth HAB errors

[jd-bootlin]

Hello,

I'm trying to implement secure boot on an i.MX8MP-based custom platform. The board design is very similar to the i.MX8MP devkit.

I want to use the Fast Authentication feature. So far, I've burnt the key hash into the SoC and I got the following HAB errors:

u-boot=> hab_status

Secure boot disabled

HAB Configuration: 0xf0, HAB State: 0x66

--------- HAB Event 1 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x1d 0xc0 0x00
0xca 0x00 0x0c 0x00 0x01 0xc5 0x1d 0x00
0x00 0x00 0x10 0xe8

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_KEY (0x1D)
CTX = HAB_CTX_COMMAND (0xC0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 2 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x1d 0xc0 0x00
0xca 0x00 0x0c 0x00 0x01 0xc5 0x1d 0x00
0x00 0x00 0x10 0xe8

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_KEY (0x1D)
CTX = HAB_CTX_COMMAND (0xC0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 3 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x1d 0xc0 0x00
0xca 0x00 0x0c 0x00 0x01 0xc5 0x1d 0x00
0x00 0x00 0x10 0xd0

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_KEY (0x1D)
CTX = HAB_CTX_COMMAND (0xC0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 4 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x1d 0xc0 0x00
0xca 0x00 0x0c 0x00 0x01 0xc5 0x1d 0x00
0x00 0x00 0x10 0xd0

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_KEY (0x1D)
CTX = HAB_CTX_COMMAND (0xC0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 5 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x0c 0xa0 0x00
0x00 0x00 0x00 0x00 0x00 0x91 0xff 0xc0
0x00 0x00 0x00 0x20

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_ASSERTION (0x0C)
CTX = HAB_CTX_ASSERT (0xA0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 6 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x0c 0xa0 0x00
0x00 0x00 0x00 0x00 0x00 0x91 0xff 0xe0
0x00 0x00 0x00 0x0c

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_ASSERTION (0x0C)
CTX = HAB_CTX_ASSERT (0xA0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 7 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x0c 0xa0 0x00
0x00 0x00 0x00 0x00 0x00 0x92 0x00 0x00
0x00 0x00 0x00 0x04

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_ASSERTION (0x0C)
CTX = HAB_CTX_ASSERT (0xA0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 8 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x0c 0xa0 0x00
0x00 0x00 0x00 0x00 0x40 0x1f 0xbd 0xc0
0x00 0x00 0x00 0x20

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_ASSERTION (0x0C)
CTX = HAB_CTX_ASSERT (0xA0)
ENG = HAB_ENG_ANY (0x00)


--------- HAB Event 9 -----------------
event data:
0xdb 0x00 0x14 0x45 0x33 0x0c 0xa0 0x00
0x00 0x00 0x00 0x00 0x40 0x1f 0xad 0xc0
0x00 0x00 0x00 0x04

STS = HAB_FAILURE (0x33)
RSN = HAB_INV_ASSERTION (0x0C)
CTX = HAB_CTX_ASSERT (0xA0)
ENG = HAB_ENG_ANY (0x00)

It looks like my key is invalid. I double checked that I fused the correct keys and it looks good to me.

Here is my full procedure, if you see something wrong:

PKI tree generation:

$ ./keys/hab4_pki_tree.sh 
Do you want to use an existing CA key (y/n)?: n

Key type options (confirm targeted device supports desired key type):
Select the key type (possible values: rsa, rsa-pss, ecc)?: rsa-pss
Enter key length in bits for PKI tree: 4096
Enter PKI tree duration (years): 5
How many Super Root Keys should be generated? 4
Do you want the SRK certificates to have the CA flag set? (y/n)?: n

 SRK table/fuse generation:

$ ./linux64/bin/srktool -h 4 -t SRK_1_2_3_4_table.bin -e SRK_1_2_3_4_fuse.bin -d sha256 -c crts/SRK1_sha256_4096_65537_v3_usr_crt.pem,crts/SRK2_sha256_4096_65537_v3_usr_crt.pem,crts/SRK3_sha256_4096_65537_v3_usr_crt.pem,crts/SRK4_sha256_4096_65537_v3_usr_crt.pem
Number of certificates    = 4
SRK table binary filename = SRK_1_2_3_4_table.bin
SRK Fuse binary filename  = SRK_1_2_3_4_fuse.bin
SRK Fuse binary dump:
SRKH[0] = 0xCC68B1A5
SRKH[1] = 0xFC739529
SRKH[2] = 0xC2A266D4
SRKH[3] = 0x565ED742
SRKH[4] = 0xD85265D5
SRKH[5] = 0x2E4D871A
SRKH[6] = 0x6AAF0D93
SRKH[7] = 0x21C75F71

Hexdump output:

$ hexdump -e '/4 "0x"' -e '/4 "%X""\n"' SRK_1_2_3_4_fuse.bin
0xCC68B1A5
0xFC739529
0xC2A266D4
0x565ED742
0xD85265D5
0x2E4D871A
0x6AAF0D93
0x21C75F71

Fuse reads on target after being burnt:

u-boot=> fuse read 6 0 4
Reading bank 6:

Word 0x00000000: cc68b1a5 fc739529 c2a266d4 565ed742
u-boot=> fuse read 7 0 4
Reading bank 7:

Word 0x00000000: d85265d5 2e4d871a 6aaf0d93 21c75f71

For the signing procedure, you'll find attached my CSF templates and imx-mkimage build logs.

I'm using CST version 4.0.0.

And for the CSF binaries generation and injection:

$ ./linux64/bin/cst -i cst_spl.txt -o cst_spl.bin
CSF Processed successfully and signed data available in cst_spl.bin

$ ./linux64/bin/cst -i cst_fit.txt -o cst_fit.bin
CSF Processed successfully and signed data available in cst_fit.bin

$ cp flash.bin signed_flash.bin

$ dd if=cst_spl.bin of=signed_flash.bin seek=$((0x36c00)) bs=1 conv=notrunc

$ dd if=cst_fit.bin of=signed_flash.bin seek=$((0x59020)) bs=1 conv=notrunc

$ sudo dd if=signed_flash.bin of=/dev/sdb bs=1K seek=32 && sync

[Harvey021 · Accepted solution]

Hello @jd-bootlin 

The i.MX8MP doesn't support RSA-PSS key for HAB. Suggest to Key Type - RSA.

Regards

Harvey

[jd-bootlin]

Hello @Harvey021, thanks for your feedback!
Do you know if it is written somewhere? I read multiple times the official CST doc and I did not find this information.

[Harvey021]

For its detailed information, recommend to have a reference to the section <HAB Feature summary> of SRM. 

Regards

Harvey

[jd-bootlin]

After decoding the first HAB event using the HABv4 API document, it looks like the reason is "specified key is identified as a CA key." I double checked my keys and they don't have the CA flag set, I'm a little bit more confused now.