notation

type Descriptor struct {
	// MediaType is the media type of the targeted content.
	MediaType string `json:"mediaType"`

	// Digest is the digest of the targeted content.
	Digest digest.Digest `json:"digest"`

	// Size specifies the size in bytes of the blob.
	Size int64 `json:"size"`

	// Annotations contains optional user defined attributes.
	Annotations map[string]string `json:"annotations,omitempty"`
}

type Service interface {
	Signer
	Verifier
}

type SignOptions struct {
	// Expiry identifies the expiration time of the resulted signature.
	Expiry time.Time
}

type Signer interface {
	// Sign signs the artifact described by its descriptor,
	// and returns the signature.
	Sign(ctx context.Context, desc Descriptor, opts SignOptions) ([]byte, error)
}

type Verifier interface {
	// Verify verifies the signature and returns the verified descriptor and
	// metadata of the signed artifact.
	Verify(ctx context.Context, signature []byte, opts VerifyOptions) (Descriptor, error)
}

type VerifyOptions struct{}