ESP32S3 Pico HSM freezes when generating RSA or ECC keys after importing DKEK

[rrottmann]

Steps to reproduce:

1. Initialize ESP32S3 Pico HSM using pico-hsm-tool.py.
2. Reinitialize the HSM using the default SO-PIN with scsh3 and set up a "standard" layout with 4 Key Domains and a single DKEK share, storing it as an encrypted file.
3. Import the DKEK into a Key Domain.
4. Attempt to generate an RSA or ECC key in the Key Domain.

Expected behavior:
The key generation process should complete successfully.

Actual behavior:
The key generation hangs indefinitely, displaying a message indicating that it may take a minute. (I know that random pool might run dry and operations might take longer on ESP32S3). The Pico HSM appears to freeze, requiring a physical disconnect to recover.

Additional information:
scsh3 APDU trace does not show any unusual activity.
No error messages are present in dmesg regarding key disconnection.

[fastchain]

+1. Seen similar behavior, but during the import of a key with dkek (not generation).

[polhenarejos]

@rrottmann Do you generate ECC or RSA? RSA is extremely slow.
I followed your setup 1-4 but I cannot reproduce it.

I'm using SCS3 3.17.566 and generated a brainpool256r1 ECC keypair.

I'll try with importing.

EDIT: I tried generating a RSA 1024 in the Keydomain 1 and it took 25 minutes. RSA 20248 would take hours.

[polhenarejos]

@fastchain I tried importing ECC and RSA keys with the previous setup and it worked correctly. Do you have a guide step by step to reproduce it?
Also, which boards do you use?

[rrottmann]

I believe the problem is related to the hardware. I tested it with a Waveshare module, and it functions properly, but with a module from Aliexpress, I can only generate ECC keys without Key Domains.

Using the Waveshare, RSA 2048 was generated in 1-2 minutes. I use the Pico Key patched SCS3 3.18.39 with Debian 12.8 and openjdk-17 on aarch64.

The Aliexpress ESP32S3 kinda works but not with imported DKEK:

[polhenarejos]

KCV is 00000, which means is not properly loaded. It usually appears when no PIN is introduced, but I see you are already logged.
Which curve are you trying to import?
Are you importing a wky file or a pkcs12?
If you are using wky, it has to be exported from a key domain with the same DKEK. You cannot import wky of a key that belongs to another key domain.

[fastchain]

@polhenarejos
I made few more tests and it looks I have a slightly different problem, so I opened separate issue
#68