Literal values in `c2pa.types.X`

[guiyrt]

In the context of text-to-image generative models, I was looking into incorporating the ingredients c2pa.types.generator.seed and c2pa.types.generator.prompt for reproducibility. I couldn't find tests or examples for seed, so I ended up using "text/plain" for both. My questions are:

1. Can ingredients not be associated with resources? I wanted to pass seed as 64-bit integer, for example, which doesn't need to be a resource, as it won't have a manifest to be verified (same applied to prompt text to some degree).
2. In the manifest examples that I saw, many of them had action with the field ingredients in parameters, but I couldn't tell if that was the final generated manifest or input manifest. Can ingredients be pre-defined inside each action?

Code using Python API

import os
import io
import c2pa

# set up paths to the files we we are using
testFile = os.path.join("A.jpg")
pemFile = os.path.join("es256_certs.pem")
keyFile = os.path.join("es256_private.key")
testOutputFile = os.path.join("dnt.jpg")

# define a manifest with the do not train assertion
manifest_json = {
    "claim_generator_info": [{
        "name": "MyProgram",
        "version": "0.0.1"
    }],
    "title": "AI-generated Image",
    "assertions": [
        {
            "label": "c2pa.training-mining",
            "data": {
                "entries": {
                "c2pa.ai_generative_training": {"use": "allowed"},
                "c2pa.ai_inference": {"use": "allowed"},
                "c2pa.ai_training": {"use": "allowed"},
                "c2pa.data_mining": {"use": "allowed"}
                }
            }
        },
        {
            "label": "c2pa.actions",
            "data": {
                "actions": [
                    {
                        "action": "c2pa.created",
                        "digitalSourceType": "http://cv.iptc.org/newscodes/digitalsourcetype/trainedAlgorithmicMedia",
                    }
                ]
            }
        }
    ],
    "ingredients": [
        {
            "title": "Prompt",
            "format": "text/plain",
            "relationship": "inputTo",
            "data": {
                "format": "text/plain",
                "identifier": "prompt",
                "data_types": [{"type": "c2pa.types.generator.prompt"}]
            }
        },
        {
            "title": "Seed",
            "format": "text/plain",
            "relationship": "inputTo",
            "data": {
                "format": "text/plain",
                "identifier": "seed",
                "data_types": [{"type": "c2pa.types.generator.seed"}]
            }
        }
    ]
}

# This could be implemented on a server using an HSM
key = open("ps256.pem","rb").read()
certs = open("ps256.pub","rb").read()

# Create a signer from a certificate pem file
builder = c2pa.Builder(manifest_json)

builder.add_resource("prompt", io.BytesIO(b"This is my prompt!"))
builder.add_resource("seed", io.BytesIO(b"42"))

if os.path.exists(testOutputFile):
    os.remove(testOutputFile)

signer = c2pa.create_signer(lambda data: c2pa.sign_ps256(data, key), c2pa.SigningAlg.PS256, certs, "http://timestamp.digicert.com")
result = builder.sign_file(signer, testFile, testOutputFile)