Error in offline validation when using additional annotations

[cck1860]

Description

When using annotations, I am able to validate them by using the signature being stored in the registry but not when using the offline validation capability.

For being able to recreate the tasks I did:

cosign sign --upload=false --key awskms:///arn:aws:kms:eu-west-3:xxxxxx:alias/cosign-key -a appname=myapp --output-signature=mysig1.sig xxx/yyy:latest

cosign verify -a appname=myapp --key cosign.pub --signature mysig1.sig xxx/yyy:latest

I'm getting the following error message:
WARNING: using obsolete implied signature payload data (with digested reference index.docker.io/xxx/bla@sha256:db071ebcec3e74bfb9a6e0358a233f7b4cc38585d3201239b9239d2e287d7e9a); specify it explicitly with --payload instead
Error: no matching signatures: searching log query: [POST /api/v1/log/entries/retrieve][400] searchLogQueryBadRequest &{Code:400 Message:verifying signature: crypto/rsa: verification error}
main.go:69: error during command execution: no matching signatures: searching log query: [POST /api/v1/log/entries/retrieve][400] searchLogQueryBadRequest &{Code:400 Message:verifying signature: crypto/rsa: verification error}

When doing the validation online without having specified --upload=false or not specifying any annotation and doing then the offline validation by using --signature=mysig1.sig the validation is successful.

I am not sure if this is actually a bug but when reading the documentation my expectation is that cosign verify -a appname=myapp --key cosign.pub --signature mysig1.sig xxx/yyy:latest should work in general.

Version

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cosign: A tool for Container Signing, Verification and Storage in an OCI registry.

GitVersion: 2.4.1
GitCommit: 9a4cfe1
GitTreeState: "clean"
BuildDate: 2024-10-03T17:01:50Z
GoVersion: go1.23.2
Compiler: gc
Platform: darwin/arm64