diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/encryption.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/encryption.go
new file mode 100644
index 0000000..0ec8b99
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/encryption.go
@@ -0,0 +1,80 @@
+// Package rfc4757 provides encryption and checksum methods as specified in RFC 4757
+package rfc4757
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/rc4"
+	"errors"
+	"fmt"
+
+	"gopkg.in/jcmturner/gokrb5.v7/crypto/etype"
+)
+
+// EncryptData encrypts the data provided using methods specific to the etype provided as defined in RFC 4757.
+func EncryptData(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))
+	}
+	rc4Cipher, err := rc4.NewCipher(key)
+	if err != nil {
+		return []byte{}, fmt.Errorf("error creating RC4 cipher: %v", err)
+	}
+	ed := make([]byte, len(data))
+	copy(ed, data)
+	rc4Cipher.XORKeyStream(ed, ed)
+	rc4Cipher.Reset()
+	return ed, nil
+}
+
+// DecryptData decrypts the data provided using the methods specific to the etype provided as defined in RFC 4757.
+func DecryptData(key, data []byte, e etype.EType) ([]byte, error) {
+	return EncryptData(key, data, e)
+}
+
+// EncryptMessage encrypts the message provided using the methods specific to the etype provided as defined in RFC 4757.
+// The encrypted data is concatenated with its RC4 header containing integrity checksum and confounder to create an encrypted message.
+func EncryptMessage(key, data []byte, usage uint32, export bool, e etype.EType) ([]byte, error) {
+	confounder := make([]byte, e.GetConfounderByteSize()) // size = 8
+	_, err := rand.Read(confounder)
+	if err != nil {
+		return []byte{}, fmt.Errorf("error generating confounder: %v", err)
+	}
+	k1 := key
+	k2 := HMAC(k1, UsageToMSMsgType(usage))
+	toenc := append(confounder, data...)
+	chksum := HMAC(k2, toenc)
+	k3 := HMAC(k2, chksum)
+
+	ed, err := EncryptData(k3, toenc, e)
+	if err != nil {
+		return []byte{}, fmt.Errorf("error encrypting data: %v", err)
+	}
+
+	msg := append(chksum, ed...)
+	return msg, nil
+}
+
+// DecryptMessage decrypts the message provided using the methods specific to the etype provided as defined in RFC 4757.
+// The integrity of the message is also verified.
+func DecryptMessage(key, data []byte, usage uint32, export bool, e etype.EType) ([]byte, error) {
+	checksum := data[:e.GetHMACBitLength()/8]
+	ct := data[e.GetHMACBitLength()/8:]
+	_, k2, k3 := deriveKeys(key, checksum, usage, export)
+
+	pt, err := DecryptData(k3, ct, e)
+	if err != nil {
+		return []byte{}, fmt.Errorf("error decrypting data: %v", err)
+	}
+
+	if !VerifyIntegrity(k2, pt, data, e) {
+		return []byte{}, errors.New("integrity checksum incorrect")
+	}
+	return pt[e.GetConfounderByteSize():], nil
+}
+
+// VerifyIntegrity checks the integrity checksum of the data matches that calculated from the decrypted data.
+func VerifyIntegrity(key, pt, data []byte, e etype.EType) bool {
+	chksum := HMAC(key, pt)
+	return hmac.Equal(chksum, data[:e.GetHMACBitLength()/8])
+}