WIP [VOL-2811] - Incorporate preliminary onu-adapter-go code into opencord repo

- reason "discovery-mibsync-complete" reached (via full MibUpload only, received data won't be stored yet)
- first review comments of patchset #4 considered
 (please have a look into our inline-comments in Gerrit to know more about the current state)
- no refactoring done yet

Change-Id: Iac47817f8ce4bd28dd8132f530b0570d57ae99b8
Signed-off-by: Holger Hildebrandt <holger.hildebrandt@adtran.com>
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc3962/encryption.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc3962/encryption.go
new file mode 100644
index 0000000..2be2fde
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc3962/encryption.go
@@ -0,0 +1,89 @@
+// Package rfc3962 provides encryption and checksum methods as specified in RFC 3962
+package rfc3962
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+
+	"gopkg.in/jcmturner/aescts.v1"
+	"gopkg.in/jcmturner/gokrb5.v7/crypto/common"
+	"gopkg.in/jcmturner/gokrb5.v7/crypto/etype"
+)
+
+// EncryptData encrypts the data provided using methods specific to the etype provided as defined in RFC 3962.
+func EncryptData(key, data []byte, e etype.EType) ([]byte, []byte, error) {
+	if len(key) != e.GetKeyByteSize() {
+		return []byte{}, []byte{}, fmt.Errorf("incorrect keysize: expected: %v actual: %v", e.GetKeyByteSize(), len(key))
+	}
+	ivz := make([]byte, e.GetCypherBlockBitLength()/8)
+	return aescts.Encrypt(key, ivz, data)
+}
+
+// EncryptMessage encrypts the message provided using the methods specific to the etype provided as defined in RFC 3962.
+// The encrypted data is concatenated with its integrity hash to create an encrypted message.
+func EncryptMessage(key, message []byte, usage uint32, e etype.EType) ([]byte, []byte, error) {
+	if len(key) != e.GetKeyByteSize() {
+		return []byte{}, []byte{}, fmt.Errorf("incorrect keysize: expected: %v actual: %v", e.GetKeyByteSize(), len(key))
+	}
+	//confounder
+	c := make([]byte, e.GetConfounderByteSize())
+	_, err := rand.Read(c)
+	if err != nil {
+		return []byte{}, []byte{}, fmt.Errorf("could not generate random confounder: %v", err)
+	}
+	plainBytes := append(c, message...)
+
+	// Derive key for encryption from usage
+	var k []byte
+	if usage != 0 {
+		k, err = e.DeriveKey(key, common.GetUsageKe(usage))
+		if err != nil {
+			return []byte{}, []byte{}, fmt.Errorf("error deriving key for encryption: %v", err)
+		}
+	}
+
+	// Encrypt the data
+	iv, b, err := e.EncryptData(k, plainBytes)
+	if err != nil {
+		return iv, b, fmt.Errorf("error encrypting data: %v", err)
+	}
+
+	// Generate and append integrity hash
+	ih, err := common.GetIntegrityHash(plainBytes, key, usage, e)
+	if err != nil {
+		return iv, b, fmt.Errorf("error encrypting data: %v", err)
+	}
+	b = append(b, ih...)
+	return iv, b, nil
+}
+
+// DecryptData decrypts the data provided using the methods specific to the etype provided as defined in RFC 3962.
+func DecryptData(key, data []byte, e etype.EType) ([]byte, error) {
+	if len(key) != e.GetKeyByteSize() {
+		return []byte{}, fmt.Errorf("incorrect keysize: expected: %v actual: %v", e.GetKeyByteSize(), len(key))
+	}
+	ivz := make([]byte, e.GetCypherBlockBitLength()/8)
+	return aescts.Decrypt(key, ivz, data)
+}
+
+// DecryptMessage decrypts the message provided using the methods specific to the etype provided as defined in RFC 3962.
+// The integrity of the message is also verified.
+func DecryptMessage(key, ciphertext []byte, usage uint32, e etype.EType) ([]byte, error) {
+	//Derive the key
+	k, err := e.DeriveKey(key, common.GetUsageKe(usage))
+	if err != nil {
+		return nil, fmt.Errorf("error deriving key: %v", err)
+	}
+	// Strip off the checksum from the end
+	b, err := e.DecryptData(k, ciphertext[:len(ciphertext)-e.GetHMACBitLength()/8])
+	if err != nil {
+		return nil, err
+	}
+	//Verify checksum
+	if !e.VerifyIntegrity(key, ciphertext, b, usage) {
+		return nil, errors.New("integrity verification failed")
+	}
+	//Remove the confounder bytes
+	return b[e.GetConfounderByteSize():], nil
+}