feat: add policy, oci, attestation

pkg/attestation/types.go

@@ -0,0 +1,35 @@
+package attestation
+
+import "encoding/base64"
+
+const (
+	DockerDsseExtKind = "application/vnd.docker.attestation-verification.v1+json"
+	RekorTlExtKind    = "Rekor"
+)
+
+var base64Encoding = base64.StdEncoding.Strict()
+
+// 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"`
+}
+type Extension struct {
+	Kind string              `json:"kind"`
+	Ext  DockerDsseExtension `json:"ext"`
+}
+
+type DockerDsseExtension struct {
+	Tl DockerTlExtension `json:"tl"`
+}
+
+type DockerTlExtension struct {
+	Kind string `json:"kind"`
+	Data any    `json:"data"`
+}