refactor! remove pkg directory (#145)

* refactor!: remove pkg directory

* chore: include breaking changes in draft

attestation/types.go

@@ -0,0 +1,113 @@
+package attestation
+
+import (
+	"encoding/base64"
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	v02 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v0.2"
+	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+const (
+	DockerReferenceType           = "vnd.docker.reference.type"
+	AttestationManifestType       = "attestation-manifest"
+	InTotoPredicateType           = "in-toto.io/predicate-type"
+	DockerReferenceDigest         = "vnd.docker.reference.digest"
+	DockerDSSEExtKind             = "application/vnd.docker.attestation-verification.v1+json"
+	RekorTLExtKind                = "Rekor"
+	OCIDescriptorDSSEMediaType    = ociv1.MediaTypeDescriptor + "+dsse"
+	InTotoReferenceLifecycleStage = "vnd.docker.lifecycle-stage"
+	LifecycleStageExperimental    = "experimental"
+)
+
+var base64Encoding = base64.StdEncoding.Strict()
+
+type Layer struct {
+	Statement   *intoto.Statement
+	Layer       v1.Layer
+	Annotations map[string]string
+}
+
+type Manifest struct {
+	OriginalDescriptor *v1.Descriptor
+	OriginalLayers     []*Layer
+
+	// accumulated during signing
+	SignedLayers []*Layer
+	// details of subject image
+	SubjectName       string
+	SubjectDescriptor *v1.Descriptor
+}
+
+type ManifestImageOptions struct {
+	// how to output the image
+	skipSubject   bool
+	replaceLayers bool
+	laxReferrers  bool
+}
+
+// the following types are needed until https://github.com/secure-systems-lab/dsse/pull/61 is merged.
+type Envelope struct {
+	PayloadType string       `json:"payloadType"`
+	Payload     string       `json:"payload"`
+	Signatures  []*Signature `json:"signatures"`
+}
+type Signature struct {
+	KeyID     string     `json:"keyid"`
+	Sig       string     `json:"sig"`
+	Extension *Extension `json:"extension,omitempty"`
+}
+type Extension struct {
+	Kind string               `json:"kind"`
+	Ext  *DockerDSSEExtension `json:"ext"`
+}
+
+type AnnotatedStatement struct {
+	OCIDescriptor   *v1.Descriptor
+	InTotoStatement *intoto.Statement
+	Annotations     map[string]string
+}
+
+type DockerDSSEExtension struct {
+	TL *DockerTLExtension `json:"tl"`
+}
+
+type DockerTLExtension struct {
+	Kind string `json:"kind"`
+	Data any    `json:"data"`
+}
+
+type VerifyOptions struct {
+	Keys   []*KeyMetadata `json:"keys"`
+	SkipTL bool           `json:"skip_tl"`
+}
+
+type SigningOptions struct {
+	// don't log to the configured transparency log
+	SkipTL bool
+}
+
+type Options struct {
+	NoReferrers   bool
+	Attach        bool
+	ReferrersRepo string
+}
+
+func DSSEMediaType(predicateType string) (string, error) {
+	var predicateName string
+	switch predicateType {
+	case v02.PredicateSLSAProvenance:
+		predicateName = "provenance"
+	case intoto.PredicateSPDX:
+		predicateName = "spdx"
+	case VSAPredicateType:
+		predicateName = "verification_summary"
+
+	default:
+		return "", fmt.Errorf("unknown predicate type %q", predicateType)
+	}
+
+	return fmt.Sprintf("application/vnd.in-toto.%s+dsse", predicateName), nil
+}