Function messageBlock

pkg/provenance/sign.go:291–318

messageBlock creates a message block from archive data and pre-marshalled metadata

(archiveData []byte, filename string, metadataBytes []byte)

// messageBlock creates a message block from archive data and pre-marshalled metadata
func messageBlock(archiveData []byte, filename string, metadataBytes []byte) (*bytes.Buffer, error) {
	// Checksum the archive data
	chash, err := Digest(bytes.NewBuffer(archiveData))
	if err != nil {
		return nil, err
	}

	sums := &SumCollection{
		Files: map[string]string{
			filename: "sha256:" + chash,
		},
	}

	// Buffer the metadata + checksums YAML file
	// FIXME: YAML uses ---\n as a file start indicator, but this is not legal in a PGP
	// clearsign block. So we use ...\n, which is the YAML document end marker.
	// http://yaml.org/spec/1.2/spec.html#id2800168
	b := bytes.NewBuffer(metadataBytes)
	b.WriteString("\n...\n")

	data, err := yaml.Marshal(sums)
	if err != nil {
		return nil, err
	}
	b.Write(data)

	return b, nil
}

// parseMessageBlock parses a message block and returns only checksums (metadata ignored like upstream)
func parseMessageBlock(data []byte) (*SumCollection, error) {