diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/MICToken.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/MICToken.go
new file mode 100644
index 0000000..856412b
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/MICToken.go
@@ -0,0 +1,202 @@
+package gssapi
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+
+	"gopkg.in/jcmturner/gokrb5.v7/crypto"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/keyusage"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+/*
+From RFC 4121, section 4.2.6.1:
+
+   Use of the GSS_GetMIC() call yields a token (referred as the MIC
+   token in this document), separate from the user data being protected,
+   which can be used to verify the integrity of that data as received.
+   The token has the following format:
+
+         Octet no   Name        Description
+         --------------------------------------------------------------
+         0..1     TOK_ID     Identification field.  Tokens emitted by
+                             GSS_GetMIC() contain the hex value 04 04
+                             expressed in big-endian order in this
+                             field.
+         2        Flags      Attributes field, as described in section
+                             4.2.2.
+         3..7     Filler     Contains five octets of hex value FF.
+         8..15    SND_SEQ    Sequence number field in clear text,
+                             expressed in big-endian order.
+         16..last SGN_CKSUM  Checksum of the "to-be-signed" data and
+                             octet 0..15, as described in section 4.2.4.
+
+   The Filler field is included in the checksum calculation for
+   simplicity.
+
+*/
+
+const (
+	// MICTokenFlagSentByAcceptor - this flag indicates the sender is the context acceptor.  When not set, it indicates the sender is the context initiator
+	MICTokenFlagSentByAcceptor = 1 << iota
+	// MICTokenFlagSealed - this flag indicates confidentiality is provided for.  It SHALL NOT be set in MIC tokens
+	MICTokenFlagSealed
+	// MICTokenFlagAcceptorSubkey - a subkey asserted by the context acceptor is used to protect the message
+	MICTokenFlagAcceptorSubkey
+)
+
+const (
+	micHdrLen = 16 // Length of the MIC Token's header
+)
+
+// MICToken represents a GSS API MIC token, as defined in RFC 4121.
+// It contains the header fields, the payload (this is not transmitted) and
+// the checksum, and provides the logic for converting to/from bytes plus
+// computing and verifying checksums
+type MICToken struct {
+	// const GSS Token ID: 0x0404
+	Flags byte // contains three flags: acceptor, sealed, acceptor subkey
+	// const Filler: 0xFF 0xFF 0xFF 0xFF 0xFF
+	SndSeqNum uint64 // sender's sequence number. big-endian
+	Payload   []byte // your data! :)
+	Checksum  []byte // checksum of { payload | header }
+}
+
+// Return the 2 bytes identifying a GSS API MIC token
+func getGSSMICTokenID() *[2]byte {
+	return &[2]byte{0x04, 0x04}
+}
+
+// Return the filler bytes used in header
+func fillerBytes() *[5]byte {
+	return &[5]byte{0xFF, 0xFF, 0xFF, 0xFF, 0xFF}
+}
+
+// Marshal the MICToken into a byte slice.
+// The payload should have been set and the checksum computed, otherwise an error is returned.
+func (mt *MICToken) Marshal() ([]byte, error) {
+	if mt.Checksum == nil {
+		return nil, errors.New("checksum has not been set")
+	}
+
+	bytes := make([]byte, micHdrLen+len(mt.Checksum))
+	copy(bytes[0:micHdrLen], mt.getMICChecksumHeader()[:])
+	copy(bytes[micHdrLen:], mt.Checksum)
+
+	return bytes, nil
+}
+
+// SetChecksum uses the passed encryption key and key usage to compute the checksum over the payload and
+// the header, and sets the Checksum field of this MICToken.
+// If the payload has not been set or the checksum has already been set, an error is returned.
+func (mt *MICToken) SetChecksum(key types.EncryptionKey, keyUsage uint32) error {
+	if mt.Checksum != nil {
+		return errors.New("checksum has already been computed")
+	}
+	checksum, err := mt.checksum(key, keyUsage)
+	if err != nil {
+		return err
+	}
+	mt.Checksum = checksum
+	return nil
+}
+
+// Compute and return the checksum of this token, computed using the passed key and key usage.
+// Confirms to RFC 4121 in that the checksum will be computed over { body | header }.
+// In the context of Kerberos MIC tokens, mostly keyusage GSSAPI_ACCEPTOR_SIGN (=23)
+// and GSSAPI_INITIATOR_SIGN (=25) will be used.
+// Note: This will NOT update the struct's Checksum field.
+func (mt *MICToken) checksum(key types.EncryptionKey, keyUsage uint32) ([]byte, error) {
+	if mt.Payload == nil {
+		return nil, errors.New("cannot compute checksum with uninitialized payload")
+	}
+	d := make([]byte, micHdrLen+len(mt.Payload))
+	copy(d[0:], mt.Payload)
+	copy(d[len(mt.Payload):], mt.getMICChecksumHeader())
+
+	encType, err := crypto.GetEtype(key.KeyType)
+	if err != nil {
+		return nil, err
+	}
+	return encType.GetChecksumHash(key.KeyValue, d, keyUsage)
+}
+
+// Build a header suitable for a checksum computation
+func (mt *MICToken) getMICChecksumHeader() []byte {
+	header := make([]byte, micHdrLen)
+	copy(header[0:2], getGSSMICTokenID()[:])
+	header[2] = mt.Flags
+	copy(header[3:8], fillerBytes()[:])
+	binary.BigEndian.PutUint64(header[8:16], mt.SndSeqNum)
+	return header
+}
+
+// Verify computes the token's checksum with the provided key and usage,
+// and compares it to the checksum present in the token.
+// In case of any failure, (false, err) is returned, with err an explanatory error.
+func (mt *MICToken) Verify(key types.EncryptionKey, keyUsage uint32) (bool, error) {
+	computed, err := mt.checksum(key, keyUsage)
+	if err != nil {
+		return false, err
+	}
+	if !hmac.Equal(computed, mt.Checksum) {
+		return false, fmt.Errorf(
+			"checksum mismatch. Computed: %s, Contained in token: %s",
+			hex.EncodeToString(computed), hex.EncodeToString(mt.Checksum))
+	}
+	return true, nil
+}
+
+// Unmarshal bytes into the corresponding MICToken.
+// If expectFromAcceptor is true we expect the token to have been emitted by the gss acceptor,
+// and will check the according flag, returning an error if the token does not match the expectation.
+func (mt *MICToken) Unmarshal(b []byte, expectFromAcceptor bool) error {
+	if len(b) < micHdrLen {
+		return errors.New("bytes shorter than header length")
+	}
+	if !bytes.Equal(getGSSMICTokenID()[:], b[0:2]) {
+		return fmt.Errorf("wrong Token ID, Expected %s, was %s",
+			hex.EncodeToString(getGSSMICTokenID()[:]),
+			hex.EncodeToString(b[0:2]))
+	}
+	flags := b[2]
+	isFromAcceptor := flags&MICTokenFlagSentByAcceptor != 0
+	if isFromAcceptor && !expectFromAcceptor {
+		return errors.New("unexpected acceptor flag is set: not expecting a token from the acceptor")
+	}
+	if !isFromAcceptor && expectFromAcceptor {
+		return errors.New("unexpected acceptor flag is not set: expecting a token from the acceptor, not in the initiator")
+	}
+	if !bytes.Equal(b[3:8], fillerBytes()[:]) {
+		return fmt.Errorf("unexpected filler bytes: expecting %s, was %s",
+			hex.EncodeToString(fillerBytes()[:]),
+			hex.EncodeToString(b[3:8]))
+	}
+
+	mt.Flags = flags
+	mt.SndSeqNum = binary.BigEndian.Uint64(b[8:16])
+	mt.Checksum = b[micHdrLen:]
+	return nil
+}
+
+// NewInitiatorMICToken builds a new initiator token (acceptor flag will be set to 0) and computes the authenticated checksum.
+// Other flags are set to 0.
+// Note that in certain circumstances you may need to provide a sequence number that has been defined earlier.
+// This is currently not supported.
+func NewInitiatorMICToken(payload []byte, key types.EncryptionKey) (*MICToken, error) {
+	token := MICToken{
+		Flags:     0x00,
+		SndSeqNum: 0,
+		Payload:   payload,
+	}
+
+	if err := token.SetChecksum(key, keyusage.GSSAPI_INITIATOR_SIGN); err != nil {
+		return nil, err
+	}
+
+	return &token, nil
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/README.md b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/README.md
new file mode 100644
index 0000000..8fdcf70
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/README.md
@@ -0,0 +1,20 @@
+# Notes on GSS-API Negotiation Mechanism
+https://tools.ietf.org/html/rfc4178
+
+Client sends an initial negotiation message to the server which specifies the list of mechanisms 
+the client can support in order of decreasing preference.
+This message is generated with the ``NewNegTokenInitKrb5`` method.
+The message generated by this function specifies only a kerberos v5 mechanism is supported.
+
+The RFC states that this message can optionally contain the initial mechanism token 
+for the preferred mechanism (KRB5 in this case) of the client. The ``NewNegTokenInitKrb5`` 
+includes this in the message.
+
+The server side responds to this message with a one of four messages:
+
+| Message Type/State | Description |
+|--------------------|-------------|
+| accept-completed | indicates that the initiator-selected mechanism was acceptable to the target, and that the security mechanism token embedded in the first negotiation message was sufficient to complete the authentication |
+| accept-incomplete | At least one more message is needed from the client to establish security context. |
+| reject | Negotiation is being terminated. |
+| request-mic | (this state can only be present in the first reply message from the target) indicates that the MIC token exchange is REQUIRED if per-message integrity services are available |
\ No newline at end of file
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/contextFlags.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/contextFlags.go
new file mode 100644
index 0000000..6634c6d
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/contextFlags.go
@@ -0,0 +1,25 @@
+package gssapi
+
+import "github.com/jcmturner/gofork/encoding/asn1"
+
+// GSS-API context flags assigned numbers.
+const (
+	ContextFlagDeleg    = 1
+	ContextFlagMutual   = 2
+	ContextFlagReplay   = 4
+	ContextFlagSequence = 8
+	ContextFlagConf     = 16
+	ContextFlagInteg    = 32
+	ContextFlagAnon     = 64
+)
+
+// ContextFlags flags for GSSAPI
+type ContextFlags asn1.BitString
+
+// NewContextFlags creates a new ContextFlags instance.
+func NewContextFlags() ContextFlags {
+	var c ContextFlags
+	c.BitLength = 32
+	c.Bytes = make([]byte, 4)
+	return c
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/gssapi.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/gssapi.go
new file mode 100644
index 0000000..47754d7
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/gssapi.go
@@ -0,0 +1,199 @@
+// Package gssapi implements Generic Security Services Application Program Interface required for SPNEGO kerberos authentication.
+package gssapi
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jcmturner/gofork/encoding/asn1"
+)
+
+// GSS-API OID names
+const (
+	// GSS-API OID names
+	OIDKRB5         OIDName = "KRB5"         // MechType OID for Kerberos 5
+	OIDMSLegacyKRB5 OIDName = "MSLegacyKRB5" // MechType OID for Kerberos 5
+	OIDSPNEGO       OIDName = "SPNEGO"
+)
+
+// GSS-API status values
+const (
+	StatusBadBindings = 1 << iota
+	StatusBadMech
+	StatusBadName
+	StatusBadNameType
+	StatusBadStatus
+	StatusBadSig
+	StatusBadMIC
+	StatusContextExpired
+	StatusCredentialsExpired
+	StatusDefectiveCredential
+	StatusDefectiveToken
+	StatusFailure
+	StatusNoContext
+	StatusNoCred
+	StatusBadQOP
+	StatusUnauthorized
+	StatusUnavailable
+	StatusDuplicateElement
+	StatusNameNotMN
+	StatusComplete
+	StatusContinueNeeded
+	StatusDuplicateToken
+	StatusOldToken
+	StatusUnseqToken
+	StatusGapToken
+)
+
+// ContextToken is an interface for a GSS-API context token.
+type ContextToken interface {
+	Marshal() ([]byte, error)
+	Unmarshal(b []byte) error
+	Verify() (bool, Status)
+	Context() context.Context
+}
+
+/*
+CREDENTIAL MANAGEMENT
+
+GSS_Acquire_cred             acquire credentials for use
+GSS_Release_cred             release credentials after use
+GSS_Inquire_cred             display information about credentials
+GSS_Add_cred                 construct credentials incrementally
+GSS_Inquire_cred_by_mech     display per-mechanism credential information
+
+CONTEXT-LEVEL CALLS
+
+GSS_Init_sec_context         initiate outbound security context
+GSS_Accept_sec_context       accept inbound security context
+GSS_Delete_sec_context       flush context when no longer needed
+GSS_Process_context_token    process received control token on context
+GSS_Context_time             indicate validity time remaining on context
+GSS_Inquire_context          display information about context
+GSS_Wrap_size_limit          determine GSS_Wrap token size limit
+GSS_Export_sec_context       transfer context to other process
+GSS_Import_sec_context       import transferred context
+
+PER-MESSAGE CALLS
+
+GSS_GetMIC                   apply integrity check, receive as token separate from message
+GSS_VerifyMIC                validate integrity check token along with message
+GSS_Wrap                     sign, optionally encrypt, encapsulate
+GSS_Unwrap                   decapsulate, decrypt if needed, validate integrity check
+
+SUPPORT CALLS
+
+GSS_Display_status           translate status codes to printable form
+GSS_Indicate_mechs           indicate mech_types supported on local system
+GSS_Compare_name             compare two names for equality
+GSS_Display_name             translate name to printable form
+GSS_Import_name              convert printable name to normalized form
+GSS_Release_name             free storage of normalized-form name
+GSS_Release_buffer           free storage of general GSS-allocated object
+GSS_Release_OID_set          free storage of OID set object
+GSS_Create_empty_OID_set     create empty OID set
+GSS_Add_OID_set_member       add member to OID set
+GSS_Test_OID_set_member      test if OID is member of OID set
+GSS_Inquire_names_for_mech   indicate name types supported by mechanism
+GSS_Inquire_mechs_for_name   indicates mechanisms supporting name type
+GSS_Canonicalize_name        translate name to per-mechanism form
+GSS_Export_name              externalize per-mechanism name
+GSS_Duplicate_name           duplicate name object
+*/
+
+// Mechanism is the GSS-API interface for authentication mechanisms.
+type Mechanism interface {
+	OID() asn1.ObjectIdentifier
+	AcquireCred() error                                               // acquire credentials for use (eg. AS exchange for KRB5)
+	InitSecContext() (ContextToken, error)                            // initiate outbound security context (eg TGS exchange builds AP_REQ to go into ContextToken to send to service)
+	AcceptSecContext(ct ContextToken) (bool, context.Context, Status) // service verifies the token server side to establish a context
+	MIC() MICToken                                                    // apply integrity check, receive as token separate from message
+	VerifyMIC(mt MICToken) (bool, error)                              // validate integrity check token along with message
+	Wrap(msg []byte) WrapToken                                        // sign, optionally encrypt, encapsulate
+	Unwrap(wt WrapToken) []byte                                       // decapsulate, decrypt if needed, validate integrity check
+}
+
+// OIDName is the type for defined GSS-API OIDs.
+type OIDName string
+
+// OID returns the OID for the provided OID name.
+func OID(o OIDName) asn1.ObjectIdentifier {
+	switch o {
+	case OIDSPNEGO:
+		return asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 2}
+	case OIDKRB5:
+		return asn1.ObjectIdentifier{1, 2, 840, 113554, 1, 2, 2}
+	case OIDMSLegacyKRB5:
+		return asn1.ObjectIdentifier{1, 2, 840, 48018, 1, 2, 2}
+	}
+	return asn1.ObjectIdentifier{}
+}
+
+// Status is the GSS-API status and implements the error interface.
+type Status struct {
+	Code    int
+	Message string
+}
+
+// Error returns the Status description.
+func (s Status) Error() string {
+	var str string
+	switch s.Code {
+	case StatusBadBindings:
+		str = "channel binding mismatch"
+	case StatusBadMech:
+		str = "unsupported mechanism requested"
+	case StatusBadName:
+		str = "invalid name provided"
+	case StatusBadNameType:
+		str = "name of unsupported type provided"
+	case StatusBadStatus:
+		str = "invalid input status selector"
+	case StatusBadSig:
+		str = "token had invalid integrity check"
+	case StatusBadMIC:
+		str = "preferred alias for GSS_S_BAD_SIG"
+	case StatusContextExpired:
+		str = "specified security context expired"
+	case StatusCredentialsExpired:
+		str = "expired credentials detected"
+	case StatusDefectiveCredential:
+		str = "defective credential detected"
+	case StatusDefectiveToken:
+		str = "defective token detected"
+	case StatusFailure:
+		str = "failure, unspecified at GSS-API level"
+	case StatusNoContext:
+		str = "no valid security context specified"
+	case StatusNoCred:
+		str = "no valid credentials provided"
+	case StatusBadQOP:
+		str = "unsupported QOP valu"
+	case StatusUnauthorized:
+		str = "operation unauthorized"
+	case StatusUnavailable:
+		str = "operation unavailable"
+	case StatusDuplicateElement:
+		str = "duplicate credential element requested"
+	case StatusNameNotMN:
+		str = "name contains multi-mechanism elements"
+	case StatusComplete:
+		str = "normal completion"
+	case StatusContinueNeeded:
+		str = "continuation call to routine required"
+	case StatusDuplicateToken:
+		str = "duplicate per-message token detected"
+	case StatusOldToken:
+		str = "timed-out per-message token detected"
+	case StatusUnseqToken:
+		str = "reordered (early) per-message token detected"
+	case StatusGapToken:
+		str = "skipped predecessor token(s) detected"
+	default:
+		str = "unknown GSS-API error status"
+	}
+	if s.Message != "" {
+		return fmt.Sprintf("%s: %s", str, s.Message)
+	}
+	return str
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go
new file mode 100644
index 0000000..9dbf96b
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go
@@ -0,0 +1,235 @@
+package gssapi
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+
+	"gopkg.in/jcmturner/gokrb5.v7/crypto"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/keyusage"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+/*
+From RFC 4121, section 4.2.6.2:
+
+   Use of the GSS_Wrap() call yields a token (referred as the Wrap token
+   in this document), which consists of a descriptive header, followed
+   by a body portion that contains either the input user data in
+   plaintext concatenated with the checksum, or the input user data
+   encrypted.  The GSS_Wrap() token SHALL have the following format:
+
+         Octet no   Name        Description
+         --------------------------------------------------------------
+          0..1     TOK_ID    Identification field.  Tokens emitted by
+                             GSS_Wrap() contain the hex value 05 04
+                             expressed in big-endian order in this
+                             field.
+          2        Flags     Attributes field, as described in section
+                             4.2.2.
+          3        Filler    Contains the hex value FF.
+          4..5     EC        Contains the "extra count" field, in big-
+                             endian order as described in section 4.2.3.
+          6..7     RRC       Contains the "right rotation count" in big-
+                             endian order, as described in section
+                             4.2.5.
+          8..15    SndSeqNum   Sequence number field in clear text,
+                             expressed in big-endian order.
+          16..last Data      Encrypted data for Wrap tokens with
+                             confidentiality, or plaintext data followed
+                             by the checksum for Wrap tokens without
+                             confidentiality, as described in section
+                             4.2.4.
+
+Quick notes:
+	- "EC" or "Extra Count" refers to the length of the checksum.
+	- "Flags" (complete details in section 4.2.2) is a set of bits:
+		- if bit 0 is set, it means the token was sent by the acceptor (generally the kerberized service).
+		- bit 1 indicates that the token's payload is encrypted
+ 		- bit 2 indicates if the message is protected using a subkey defined by the acceptor.
+	- When computing checksums, EC and RRC MUST be set to 0.
+    - Wrap Tokens are not ASN.1 encoded.
+*/
+const (
+	HdrLen          = 16 // Length of the Wrap Token's header
+	FillerByte byte = 0xFF
+)
+
+// WrapToken represents a GSS API Wrap token, as defined in RFC 4121.
+// It contains the header fields, the payload and the checksum, and provides
+// the logic for converting to/from bytes plus computing and verifying checksums
+type WrapToken struct {
+	// const GSS Token ID: 0x0504
+	Flags byte // contains three flags: acceptor, sealed, acceptor subkey
+	// const Filler: 0xFF
+	EC        uint16 // checksum length. big-endian
+	RRC       uint16 // right rotation count. big-endian
+	SndSeqNum uint64 // sender's sequence number. big-endian
+	Payload   []byte // your data! :)
+	CheckSum  []byte // authenticated checksum of { payload | header }
+}
+
+// Return the 2 bytes identifying a GSS API Wrap token
+func getGssWrapTokenId() *[2]byte {
+	return &[2]byte{0x05, 0x04}
+}
+
+// Marshal the WrapToken into a byte slice.
+// The payload should have been set and the checksum computed, otherwise an error is returned.
+func (wt *WrapToken) Marshal() ([]byte, error) {
+	if wt.CheckSum == nil {
+		return nil, errors.New("checksum has not been set")
+	}
+	if wt.Payload == nil {
+		return nil, errors.New("payload has not been set")
+	}
+
+	pldOffset := HdrLen                    // Offset of the payload in the token
+	chkSOffset := HdrLen + len(wt.Payload) // Offset of the checksum in the token
+
+	bytes := make([]byte, chkSOffset+int(wt.EC))
+	copy(bytes[0:], getGssWrapTokenId()[:])
+	bytes[2] = wt.Flags
+	bytes[3] = FillerByte
+	binary.BigEndian.PutUint16(bytes[4:6], wt.EC)
+	binary.BigEndian.PutUint16(bytes[6:8], wt.RRC)
+	binary.BigEndian.PutUint64(bytes[8:16], wt.SndSeqNum)
+	copy(bytes[pldOffset:], wt.Payload)
+	copy(bytes[chkSOffset:], wt.CheckSum)
+	return bytes, nil
+}
+
+// SetCheckSum uses the passed encryption key and key usage to compute the checksum over the payload and
+// the header, and sets the CheckSum field of this WrapToken.
+// If the payload has not been set or the checksum has already been set, an error is returned.
+func (wt *WrapToken) SetCheckSum(key types.EncryptionKey, keyUsage uint32) error {
+	if wt.Payload == nil {
+		return errors.New("payload has not been set")
+	}
+	if wt.CheckSum != nil {
+		return errors.New("checksum has already been computed")
+	}
+	chkSum, cErr := wt.computeCheckSum(key, keyUsage)
+	if cErr != nil {
+		return cErr
+	}
+	wt.CheckSum = chkSum
+	return nil
+}
+
+// ComputeCheckSum computes and returns the checksum of this token, computed using the passed key and key usage.
+// Conforms to RFC 4121 in that the checksum will be computed over { body | header },
+// with the EC and RRC flags zeroed out.
+// In the context of Kerberos Wrap tokens, mostly keyusage GSSAPI_ACCEPTOR_SEAL (=22)
+// and GSSAPI_INITIATOR_SEAL (=24) will be used.
+// Note: This will NOT update the struct's Checksum field.
+func (wt *WrapToken) computeCheckSum(key types.EncryptionKey, keyUsage uint32) ([]byte, error) {
+	if wt.Payload == nil {
+		return nil, errors.New("cannot compute checksum with uninitialized payload")
+	}
+	// Build a slice containing { payload | header }
+	checksumMe := make([]byte, HdrLen+len(wt.Payload))
+	copy(checksumMe[0:], wt.Payload)
+	copy(checksumMe[len(wt.Payload):], getChecksumHeader(wt.Flags, wt.SndSeqNum))
+
+	encType, err := crypto.GetEtype(key.KeyType)
+	if err != nil {
+		return nil, err
+	}
+	return encType.GetChecksumHash(key.KeyValue, checksumMe, keyUsage)
+}
+
+// Build a header suitable for a checksum computation
+func getChecksumHeader(flags byte, senderSeqNum uint64) []byte {
+	header := make([]byte, 16)
+	copy(header[0:], []byte{0x05, 0x04, flags, 0xFF, 0x00, 0x00, 0x00, 0x00})
+	binary.BigEndian.PutUint64(header[8:], senderSeqNum)
+	return header
+}
+
+// Verify computes the token's checksum with the provided key and usage,
+// and compares it to the checksum present in the token.
+// In case of any failure, (false, Err) is returned, with Err an explanatory error.
+func (wt *WrapToken) Verify(key types.EncryptionKey, keyUsage uint32) (bool, error) {
+	computed, cErr := wt.computeCheckSum(key, keyUsage)
+	if cErr != nil {
+		return false, cErr
+	}
+	if !hmac.Equal(computed, wt.CheckSum) {
+		return false, fmt.Errorf(
+			"checksum mismatch. Computed: %s, Contained in token: %s",
+			hex.EncodeToString(computed), hex.EncodeToString(wt.CheckSum))
+	}
+	return true, nil
+}
+
+// Unmarshal bytes into the corresponding WrapToken.
+// If expectFromAcceptor is true, we expect the token to have been emitted by the gss acceptor,
+// and will check the according flag, returning an error if the token does not match the expectation.
+func (wt *WrapToken) Unmarshal(b []byte, expectFromAcceptor bool) error {
+	// Check if we can read a whole header
+	if len(b) < 16 {
+		return errors.New("bytes shorter than header length")
+	}
+	// Is the Token ID correct?
+	if !bytes.Equal(getGssWrapTokenId()[:], b[0:2]) {
+		return fmt.Errorf("wrong Token ID. Expected %s, was %s",
+			hex.EncodeToString(getGssWrapTokenId()[:]),
+			hex.EncodeToString(b[0:2]))
+	}
+	// Check the acceptor flag
+	flags := b[2]
+	isFromAcceptor := flags&0x01 == 1
+	if isFromAcceptor && !expectFromAcceptor {
+		return errors.New("unexpected acceptor flag is set: not expecting a token from the acceptor")
+	}
+	if !isFromAcceptor && expectFromAcceptor {
+		return errors.New("expected acceptor flag is not set: expecting a token from the acceptor, not the initiator")
+	}
+	// Check the filler byte
+	if b[3] != FillerByte {
+		return fmt.Errorf("unexpected filler byte: expecting 0xFF, was %s ", hex.EncodeToString(b[3:4]))
+	}
+	checksumL := binary.BigEndian.Uint16(b[4:6])
+	// Sanity check on the checksum length
+	if int(checksumL) > len(b)-HdrLen {
+		return fmt.Errorf("inconsistent checksum length: %d bytes to parse, checksum length is %d", len(b), checksumL)
+	}
+
+	wt.Flags = flags
+	wt.EC = checksumL
+	wt.RRC = binary.BigEndian.Uint16(b[6:8])
+	wt.SndSeqNum = binary.BigEndian.Uint64(b[8:16])
+	wt.Payload = b[16 : len(b)-int(checksumL)]
+	wt.CheckSum = b[len(b)-int(checksumL):]
+	return nil
+}
+
+// NewInitiatorWrapToken builds a new initiator token (acceptor flag will be set to 0) and computes the authenticated checksum.
+// Other flags are set to 0, and the RRC and sequence number are initialized to 0.
+// Note that in certain circumstances you may need to provide a sequence number that has been defined earlier.
+// This is currently not supported.
+func NewInitiatorWrapToken(payload []byte, key types.EncryptionKey) (*WrapToken, error) {
+	encType, err := crypto.GetEtype(key.KeyType)
+	if err != nil {
+		return nil, err
+	}
+
+	token := WrapToken{
+		Flags: 0x00, // all zeroed out (this is a token sent by the initiator)
+		// Checksum size: length of output of the HMAC function, in bytes.
+		EC:        uint16(encType.GetHMACBitLength() / 8),
+		RRC:       0,
+		SndSeqNum: 0,
+		Payload:   payload,
+	}
+
+	if err := token.SetCheckSum(key, keyusage.GSSAPI_INITIATOR_SEAL); err != nil {
+		return nil, err
+	}
+
+	return &token, nil
+}