Image encryption/decryption support in skopeo

Signed-off-by: Harshal Patil <harshal.patil@in.ibm.com>
Signed-off-by: Brandon Lum <lumjjb@gmail.com>

vendor/github.com/containers/ocicrypt/keywrap/keywrap.go

@@ -0,0 +1,40 @@
+/*
+   Copyright The ocicrypt 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 keywrap
+
+import (
+	"github.com/containers/ocicrypt/config"
+)
+
+// KeyWrapper is the interface used for wrapping keys using
+// a specific encryption technology (pgp, jwe)
+type KeyWrapper interface {
+	WrapKeys(ec *config.EncryptConfig, optsData []byte) ([]byte, error)
+	UnwrapKey(dc *config.DecryptConfig, annotation []byte) ([]byte, error)
+	GetAnnotationID() string
+	// GetPrivateKeys (optional) gets the array of private keys. It is an optional implementation
+	// as in some key services, a private key may not be exportable (i.e. HSM)
+	GetPrivateKeys(dcparameters map[string][][]byte) [][]byte
+
+	// GetKeyIdsFromPacket (optional) gets a list of key IDs. This is optional as some encryption
+	// schemes may not have a notion of key IDs
+	GetKeyIdsFromPacket(packet string) ([]uint64, error)
+
+	// GetRecipients (optional) gets a list of recipients. It is optional due to the validity of
+	// recipients in a particular encryptiong scheme
+	GetRecipients(packet string) ([]string, error)
+}