Fix offline verification marshalling, add e2e tests. (#330)

e2e verification was failing because we were using the wrong body to
recreate the tlog message.

To test this, this also adds an e2e test that verifies a real commit
only using offline verification. This is a bit brittle at the moment
because it will mutate the local TUF client state, but this will
hopefully be improved once the TUF client changes land in
sigstore/client-go.

Signed-off-by: Billy Lynch <[email protected]>

.github/workflows/ci.yaml

@@ -25,3 +25,6 @@ jobs:
 
     - name: Unit Tests
       run: make unit-test
+
+    - name: Live dependency tests
+      run: make e2e-test

Makefile

@@ -42,3 +42,8 @@ install-all: install-gitsign install-credential-cache
 .PHONY: unit-test
 unit-test:
 	go test -v ./...
+
+# These tests use live dependencies, and may otherwise modify state.
+.PHONY: e2e-test
+e2e-test:
+	go test -tags e2e -v ./...

internal/e2e/offline_test.go

@@ -0,0 +1,65 @@
+// Copyright 2023 The Sigstore Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build e2e
+// +build e2e
+
+package e2e
+
+import (
+	"context"
+	"crypto/x509"
+	"testing"
+
+	"github.com/sigstore/gitsign/internal/fulcio/fulcioroots"
+	"github.com/sigstore/gitsign/internal/git/gittest"
+	"github.com/sigstore/gitsign/pkg/git"
+	"github.com/sigstore/gitsign/pkg/rekor"
+	"github.com/sigstore/sigstore/pkg/tuf"
+)
+
+func TestVerifyOffline(t *testing.T) {
+	ctx := context.Background()
+
+	// Initialize to prod root.
+	tuf.Initialize(ctx, tuf.DefaultRemoteRoot, nil)
+	root, intermediate, err := fulcioroots.New(x509.NewCertPool(), fulcioroots.FromTUF(ctx))
+	if err != nil {
+		t.Fatalf("error getting certificate root: %v", err)
+	}
+
+	client, err := rekor.New("https://rekor.sigstore.dev")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	commit := gittest.ParseCommit(t, "testdata/offline.commit")
+	body := gittest.MarshalCommitBody(t, commit)
+	sig := []byte(commit.PGPSignature)
+
+	verifier, err := git.NewCertVerifier(git.WithRootPool(root), git.WithIntermediatePool(intermediate))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cert, err := verifier.Verify(ctx, body, sig, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tlog, err := client.VerifyInclusion(ctx, sig, cert)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(*tlog.LogIndex)
+}

internal/e2e/testdata/offline.commit

@@ -0,0 +1,47 @@
+tree 045f683042529876c1fe28f97f416c1501ffa433
+parent 74f0d242677d95a477f953260a2686712846c619
+author Billy Lynch <[email protected]> 1685981477 -0400
+committer Billy Lynch <[email protected]> 1685981477 -0400
+gpgsig -----BEGIN SIGNED MESSAGE-----
+ MIIHPQYJKoZIhvcNAQcCoIIHLjCCByoCAQExDTALBglghkgBZQMEAgEwCwYJKoZI
+ hvcNAQcBoIIC0DCCAswwggJSoAMCAQICFAG6/a9VuUO5SlyJA02E3aCq+I7nMAoG
+ CCqGSM49BAMDMDcxFTATBgNVBAoTDHNpZ3N0b3JlLmRldjEeMBwGA1UEAxMVc2ln
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+ lVMl0NAe/AWmTBlo1LsuuVEnTnqXvagu9a1+USZ5MAoGCCqGSM49BAMCBEcwRQIg
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+ nLMhBKbUH7L3yIxCXXioSlMbbaGCAwowggMGBgorBgEEAYO/MAMBMYIC9gSCAvII
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+ 0iwYHUwKJGUY56miIL32Qyr+AQr7AXJla29yLnNpZ3N0b3JlLmRldiAtIDI2MDU3
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+ TnYrWHV2TWlyVGdmQlNaS250cz0KVGltZXN0YW1wOiAxNjg1OTgxNDgwMTg3Mzc4
+ MzQ5CgrigJQgcmVrb3Iuc2lnc3RvcmUuZGV2IHdOSTlhakJFQWlBTTE2enROTGtN
+ azRtUzNqWW02TGVKLy9CdFhkV3VXZEpjd1JQMWtLeXYwUUlnSXB1Zm15MWVHNExF
+ TGh5RjJXbVJmVHdXbldXaGJnMzlxeE5IWWpEY0x6dz0K
+ -----END SIGNED MESSAGE-----
+
+Mon Jun  5 12:11:17 EDT 2023

internal/git/gittest/testing.go

@@ -0,0 +1,67 @@
+// Copyright 2023 The Sigstore Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package gittest
+
+import (
+	"io"
+	"os"
+	"testing"
+
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/go-git/go-git/v5/storage/memory"
+)
+
+func ParseCommit(t *testing.T, path string) *object.Commit {
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("error reading input: %v", err)
+	}
+
+	storage := memory.NewStorage()
+	obj := storage.NewEncodedObject()
+	obj.SetType(plumbing.CommitObject)
+	w, err := obj.Writer()
+	if err != nil {
+		t.Fatalf("error getting git object writer: %v", err)
+	}
+	if _, err := w.Write(raw); err != nil {
+		t.Fatalf("error writing git commit: %v", err)
+	}
+
+	c, err := object.DecodeCommit(storage, obj)
+	if err != nil {
+		t.Fatalf("error decoding commit: %v", err)
+	}
+	return c
+}
+
+func MarshalCommitBody(t *testing.T, commit *object.Commit) []byte {
+	t.Helper()
+	storage := memory.NewStorage()
+	obj := storage.NewEncodedObject()
+	if err := commit.EncodeWithoutSignature(obj); err != nil {
+		t.Fatal(err)
+	}
+	r, err := obj.Reader()
+	if err != nil {
+		t.Fatal(err)
+	}
+	body, err := io.ReadAll(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return body
+}

pkg/rekor/rekor.go

@@ -280,7 +280,7 @@ func (c *Client) VerifyInclusion(ctx context.Context, sig []byte, cert *x509.Cer
 	// Get HashedRekord body from the signature.
 	// We are assuming here that the signature has already been authenticated against the
 	// cert, so it is okay to rely the precomputed checksum in the SignerInfo.
-	message, err := si.GetMessageDigestAttribute()
+	message, err := si.SignedAttrs.MarshaledForVerification()
 	if err != nil {
 		return nil, err
 	}