rust-ccatoken

rust-ccatoken is an implementation of the Arm CCA attestation token (§A.7 of the Realm Management Monitor (RMM) Specification) in Rust.

The library implements interfaces to:

• Decode a CBOR-encoded CCA token
• Verify the CCA token (Platform, Realm and their binding)
• Appraise CCA evidence using user-supplied reference values and endorsements

ccatoken CLI

Alongside the library code, this crate provides a CLI to manipulate CCA tokens.

All the examples below assume all paths are relative to the root of this repository, and that the ccatoken executable is reachable via the shell PATH. I.e.:

export PATH=$PATH:"$PWD/target/debug"

ccatoken golden

The golden command creates reference values and trust anchor for the given token and CPAK. If the token is not successfully verified with CPAK no values are extracted.

ccatoken golden \
    -e testdata/cca-token.cbor \
    -c testdata/cpak.json \
    -t golden-tastore.json \
    -r golden-rvstore.json

On success:

golden values extraction successful

the two "golden" stores are saved on disk. The contents can be pretty-printed using jq(1) as follows:

jq . golden-*.json

which should produce an output similar to the following:

{
  "platform": [
    {
      "implementation-id": "7f454c4602010100000000000000000003003e00010000005058000000000000",
      "sw-components": [
        {
          "measurement-value": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "signer-id": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "version": "3.4.2",
          "component-type": "BL"
        },
        {
          "measurement-value": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "signer-id": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "version": "1.2",
          "component-type": "M1"
        },
        {
          "measurement-value": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "signer-id": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "version": "1.2.3",
          "component-type": "M2"
        },
        {
          "measurement-value": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "signer-id": "07060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918",
          "version": "1",
          "component-type": "M3"
        }
      ],
      "platform-configuration": "0107060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918"
    }
  ],
  "realm": [
    {
      "initial-measurement": "0000000000000000000000000000000000000000000000000000000000000000",
      "rak-hash-algorithm": "sha-256",
      "extensible-measurements": [
        "0000000000000000000000000000000000000000000000000000000000000000",
        "0000000000000000000000000000000000000000000000000000000000000000",
        "0000000000000000000000000000000000000000000000000000000000000000",
        "0000000000000000000000000000000000000000000000000000000000000000"
      ],
      "personalization-value": "54686520717569636b2062726f776e20666f78206a756d7073206f766572203133206c617a7920646f67732e54686520717569636b2062726f776e20666f7820"
    }
  ]
}
[
  {
    "pkey": {
      "crv": "P-384",
      "kty": "EC",
      "x": "IShnxS4rlQiwpCCpBWDzlNLfqiG911FP8akBr-fh94uxHU5m-Kijivp2r2oxxN6M",
      "y": "hM4tr8mWQli1P61xh3T0ViDREbF26DGOEYfbAjWjGNN7pZf-6A4OTHYqEryz6m7U"
    },
    "implementation-id": "7f454c4602010100000000000000000003003e00010000005058000000000000",
    "instance-id": "0107060504030201000f0e0d0c0b0a090817161514131211101f1e1d1c1b1a1918"
  }
]

ccatoken appraise

The appraise command tries to match the supplied CCA token and reference values.

ccatoken appraise \
    -e testdata/cca-token.cbor \
    -r golden-rvstore.json

On successful completion, the computed trust vectors for the platform and realm are printed to stdout:

appraisal completed
platform trust vector: {
  "instance-identity": 2,
  "configuration": 2,
  "executables": 3,
  "hardware": 2,
  "runtime-opaque": 32
}
realm trust vector: {
  "executables": 2
}

ccatoken verify

The verify command cryptographically verifies the supplied CCA token using a matching CPAK from the trust anchor store.

ccatoken verify \
    -e testdata/cca-token.cbor \
    -t golden-tastore.json

On successful completion, the computed trust vectors for the platform and realm are printed to stdout:

verification completed
platform trust vector: {
  "instance-identity": 2
}
realm trust vector: {
  "instance-identity": 2
}