diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/checksum.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/checksum.go
new file mode 100644
index 0000000..45276e9
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/checksum.go
@@ -0,0 +1,40 @@
+package rfc4757
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/md5"
+	"io"
+)
+
+// Checksum returns a hash of the data in accordance with RFC 4757
+func Checksum(key []byte, usage uint32, data []byte) ([]byte, error) {
+	// Create hashing key
+	s := append([]byte(`signaturekey`), byte(0x00)) //includes zero octet at end
+	mac := hmac.New(md5.New, key)
+	mac.Write(s)
+	Ksign := mac.Sum(nil)
+
+	// Format data
+	tb := UsageToMSMsgType(usage)
+	p := append(tb, data...)
+	h := md5.New()
+	rb := bytes.NewReader(p)
+	_, err := io.Copy(h, rb)
+	if err != nil {
+		return []byte{}, err
+	}
+	tmp := h.Sum(nil)
+
+	// Generate HMAC
+	mac = hmac.New(md5.New, Ksign)
+	mac.Write(tmp)
+	return mac.Sum(nil), nil
+}
+
+// HMAC returns a keyed MD5 checksum of the data
+func HMAC(key []byte, data []byte) []byte {
+	mac := hmac.New(md5.New, key)
+	mac.Write(data)
+	return mac.Sum(nil)
+}
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])
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/keyDerivation.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/keyDerivation.go
new file mode 100644
index 0000000..5e7ec48
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/keyDerivation.go
@@ -0,0 +1,55 @@
+package rfc4757
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+
+	"golang.org/x/crypto/md4"
+)
+
+// StringToKey returns a key derived from the string provided according to the definition in RFC 4757.
+func StringToKey(secret string) ([]byte, error) {
+	b := make([]byte, len(secret)*2, len(secret)*2)
+	for i, r := range secret {
+		u := fmt.Sprintf("%04x", r)
+		c, err := hex.DecodeString(u)
+		if err != nil {
+			return []byte{}, errors.New("character could not be encoded")
+		}
+		// Swap round the two bytes to make little endian as we put into byte slice
+		b[2*i] = c[1]
+		b[2*i+1] = c[0]
+	}
+	r := bytes.NewReader(b)
+	h := md4.New()
+	_, err := io.Copy(h, r)
+	if err != nil {
+		return []byte{}, err
+	}
+	return h.Sum(nil), nil
+}
+
+func deriveKeys(key, checksum []byte, usage uint32, export bool) (k1, k2, k3 []byte) {
+	//if export {
+	//	L40 := make([]byte, 14, 14)
+	//	copy(L40, []byte(`fortybits`))
+	//	k1 = HMAC(key, L40)
+	//} else {
+	//	tb := MessageTypeBytes(usage)
+	//	k1 = HMAC(key, tb)
+	//}
+	//k2 = k1[:16]
+	//if export {
+	//	mask := []byte{0xAB,0xAB,0xAB,0xAB,0xAB,0xAB,0xAB,0xAB,0xAB}
+	//	copy(k1[7:16], mask)
+	//}
+	//k3 = HMAC(k1, checksum)
+	//return
+	k1 = key
+	k2 = HMAC(k1, UsageToMSMsgType(usage))
+	k3 = HMAC(k2, checksum)
+	return
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/msgtype.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/msgtype.go
new file mode 100644
index 0000000..068588d
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/crypto/rfc4757/msgtype.go
@@ -0,0 +1,20 @@
+package rfc4757
+
+import "encoding/binary"
+
+// UsageToMSMsgType converts Kerberos key usage numbers to Microsoft message type encoded as a little-endian four byte slice.
+func UsageToMSMsgType(usage uint32) []byte {
+	// Translate usage numbers to the Microsoft T numbers
+	switch usage {
+	case 3:
+		usage = 8
+	case 9:
+		usage = 8
+	case 23:
+		usage = 13
+	}
+	// Now convert to bytes
+	tb := make([]byte, 4) // We force an int32 input so we can't go over 4 bytes
+	binary.PutUvarint(tb, uint64(usage))
+	return tb
+}