feat: remove experimental on Sigstore bundle and v1.0 SLSA provenance format

README.md

@@ -379,6 +379,32 @@ release tag and `--package-version` to validate the package version. For commit
 SHA validation, use `--print-provenance` and inspect the commit SHA of the
 config source or materials.
 
+### Container-based builds
+
+To verify an artifact produced by the [Container-based builder](https://github.com/slsa-framework/slsa-github-generator/blob/main/internal/builders/docker/README.md), you will first need to run the following command to verify the provenance like the section above for general [Artifacts](#artifacts):
+
+```bash
+$ slsa-verifier verify-artifact slsa-test-linux-amd64 \
+  --provenance-path slsa-test-linux-amd64.sigstore \
+  --source-uri github.com/slsa-framework/slsa-test \
+  --source-tag v1.0.3
+Verified signature against tlog entry index 3189970 at URL: https://rekor.sigstore.dev/api/v1/log/entries/206071d5ca7a2346e4db4dcb19a648c7f13b4957e655f4382b735894059bd199
+Verified build using builder https://github.com/slsa-framework/slsa-github-generator/.github/workflows/builder_container-based_slsa3.yml@refs/tags/v1.7.0 at commit 5bb13ef508b2b8ded49f9264d7712f1316830d10
+PASSED: Verified SLSA provenance
+```
+
+The input provenance is a `.sigstore` file, which is a [Sigstore bundle](https://github.com/sigstore/protobuf-specs/blob/main/protos/sigstore_bundle.proto#L63) that contains the in-toto statement containing the SLSA provenance along with verification material. The verified in-toto statement contained in the bundle may be written to stdout with the `--print-provenance` flag to pipe into policy engines.
+
+To verify the user-specified builder image that was used to produce the artifact, extract the builder image with the following command and validate in a policy engine:
+
+```bash
+$ cat verifier-statement.intoto | jq -r '.predicate.buildDefinition.externalParameters.builderImage'
+```
+
+The builder image is described using an [in-toto Resource Descriptor](https://github.com/in-toto/attestation/blob/main/spec/v1/resource_descriptor.md).
+
+In case the builds are reproducible, you may also use the internal [docker CLI tool](https://github.com/slsa-framework/slsa-github-generator/tree/main/internal/builders/docker#the-verify-command) to verify the artifact by rebuilding the artifact with the provided provenance.
+
 ## Verification for Google Cloud Build
 
 ### Artifacts

cli/slsa-verifier/main_regression_test.go

@@ -1301,7 +1301,6 @@ func Test_runVerifyGCBArtifactImage(t *testing.T) {
 // TODO(#485): Version the test-cases when a version for the builder is released.
 func Test_runVerifyGHAContainerBased(t *testing.T) {
 	// We cannot use t.Setenv due to parallelized tests.
-	os.Setenv("SLSA_VERIFIER_EXPERIMENTAL", "1")
 	os.Setenv("SLSA_VERIFIER_TESTING", "1")
 
 	t.Parallel()

verifiers/internal/gha/verifier.go

@@ -210,9 +210,6 @@ func (v *GHAVerifier) VerifyArtifact(ctx context.Context,
 	builderOpts *options.BuilderOpts,
 ) ([]byte, *utils.TrustedBuilderID, error) {
 	isSigstoreBundle := IsSigstoreBundle(provenance)
-	if isSigstoreBundle && !options.ExperimentalEnabled() {
-		return nil, nil, errors.New("sigstore bundle support is only provided in SLSA_VERIFIER_EXPERIMENTAL mode")
-	}
 
 	// This includes a default retry count of 3.
 	rClient, err := client.GetRekorClient(defaultRekorAddr)