ctfe public key default name breaks cosign

[federico-falconieri-form3]

Description

I am not sure if this is a bug or a documentation problem. I'm leaving this here as I imagine that anyone deploying these days probably has the same issue.
I deployed scaffold 0.6.36, including tuf and got stuck with the following error with cosign v2.2.0 when performing signing

**Warning** Missing fallback target ctfe.pub, skipping
Error: getting ctlog public keys: no matching targets by custom metadata, fallbacks not found: ctfe.pub
main.go:74: error during command execution: getting ctlog public keys: no matching targets by custom metadata, fallbacks not found: ctfe.pub
Error: Process completed with exit code 1.

I also noticed that I don't have ctfe.pub in my root targets... I have ctlog_pubkey.

cosign initialize --root redacted/root.json --mirror redacted
Root status: 
 {
        "local": "redacted.../.sigstore/root",
        "remote": "redacted",
        "metadata": {
                "root.json": {
                        "version": 1,
                        "len": redacted,
                        "expiration": "redacted",
                        "error": ""
                },
                "snapshot.json": {
                        "version": 1,
                        "len": redacted,
                        "expiration": "redacted",
                        "error": ""
                },
                "targets.json": {
                        "version": 1,
                        "len": redacted,
                        "expiration": "redacted",
                        "error": ""
                },
                "timestamp.json": {
                        "version": 1,
                        "len": redacted,
                        "expiration": "redacted",
                        "error": ""
                }
        },
        "targets": [
                "rekor-pubkey",
                "ctlog-pubkey",
                "fulcio-cert"
        ]
}

This is different from what I can find in all guides online to deploy sigstore, for instance https://blog.stephane-robert.info/post/devops-cosign-rekor-private/ (it's in french, sorry, scroll down to the cosign -d initialize --root root.json --mirror https://tuf.robert.local)
Cosign does not seem to allow to override the filename, as it is hardcoded in https://github.com/sigstore/cosign/blob/878b6c766e17d59d5624c802a1e196e8e8d47f56/pkg/cosign/ctlog.go#L28.
In the end I was able to resolve this through the env variable SIGSTORE_CT_LOG_PUBLIC_KEY_FILE. But that is annoying because it requires to manually inspect the kubernetes secret to copy the public key...

PS is there a way to fetch that public key like there is for rekor api/v1/log/publicKey?

I do not understand currently if this is caused by configuration of tuf, ctlog, fulcio or the copysecrets jobs

Version

• cosign: v2.2.0
• scaffold: 0.6.36

[bobcallaway]

@kommendorkapten @haydentherapper FYI

[sabre1041]

@federico-falconieri-form3 can you share your values file or the items unique to your deployment?

[federico-falconieri-form3]

@sabre1041

Sure, however I cannot share the fulcio OIDC issuer configuration:

trillian:
  enabled: true
  namespace:
    create: true
  mysql:
    persistence:
      enabled: true

ctlog:
  enabled: true
  namespace:
    create: true

rekor:
  enabled: true
  namespace:
    create: true
  server:
    ingress:
      http:
        enabled: false # I create the ingress manually elsewhere 
    attestation_storage:
      enabled: false

fulcio:
  enabled: true
  namespace:
    create: true
  server:
    args:
      certificateAuthority: fileca
    ingress:
      http:
        enabled: false # I create the ingress manually elsewhere

tuf:
  enabled: true
  namespace:
    create: true
  ingress:
    enabled: false # I create the ingress manually elsewhere

copySecretJob:
  enabled: true

tsa:
  enabled: false

[sabre1041]

@federico-falconieri-form3 if you want to add the following, it should solve the issues that you are facing

tuf:
  secrets:
    fulcio:
      path: fulcio_v1.crt.pem
    rekor:
      path: rekor.pub
    ctlog:
      path: ctfe.pub

These will be the default values moving forward

[kommendorkapten]

Can you share the tuf targets.json config? It seems you are missing the metadata for ctlog-pubkey? Looking at Sigstore's metadata, it looks like this:

...
			"ctfe.pub": {
				"length": 177,
				"hashes": {
					"sha256": "7fcb94a5d0ed541260473b990b99a6c39864c1fb16f3f3e594a5a3cebbfe138a",
					"sha512": "4b20747d1afe2544238ad38cc0cc3010921b177d60ac743767e0ef675b915489bd01a36606c0ff83c06448622d7160f0d866c83d20f0c0f44653dcc3f9aa0bd4"
				},
				"custom": {
					"sigstore": {
						"status": "Active",
						"uri": "https://ctfe.sigstore.dev/test",
						"usage": "CTFE"
					}
				}
			},
...

So the usage attribute is what is being used to search for the correct public key.

[haydentherapper]

@kommendorkapten One issue is I think this is lagging behind some of the updates to the expected Sigstore TUF metadata, it's not setting custom. sigstore/helm-charts#673 should fix this because it uses the fallback names, but a long-term fix is to set the custom metadata too.

[kommendorkapten]

@haydentherapper ah, got it. I'm not very familiar with the scaffolding project and how the TUF repository is configured.