Initial commit of implementation

2015-10-16 21:41:57 -07:00
parent 8879b4c6f2
commit c3e922711f
13 changed files with 656 additions and 1 deletions
--- a/README.md
+++ b/README.md
@@ -1,2 +1,9 @@
 # go-ntlmssp
-NTLM/Negotiate authentication over HTTP
+Golang package that provides NTLM/Negotiate authentication over HTTP
+
+Protocol details from https://msdn.microsoft.com/en-us/library/cc236621.aspx
+Implementation hints from http://davenport.sourceforge.net/ntlm.html
+
+This package only implements authentication, no key exchange or encryption. It
+only supports Unicode (UTF16LE) encoding of protocol strings, no OEM encoding.
+This package implements NTLMv2.
--- a/authenticate_message.go
+++ b/authenticate_message.go
@@ -0,0 +1,128 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"errors"
+	"time"
+)
+
+type authenicateMessage struct {
+	LmChallengeResponse []byte
+	NtChallengeResponse []byte
+
+	TargetName string
+	UserName   string
+
+	// only set if negotiateFlag_NTLMSSP_NEGOTIATE_KEY_EXCH
+	EncryptedRandomSessionKey []byte
+
+	NegotiateFlags negotiateFlags
+
+	MIC []byte
+}
+
+type authenticateMessageFields struct {
+	messageHeader
+	LmChallengeResponse varField
+	NtChallengeResponse varField
+	TargetName          varField
+	UserName            varField
+	Workstation         varField
+	_                   [8]byte
+	NegotiateFlags      negotiateFlags
+}
+
+func (m authenicateMessage) MarshalBinary() ([]byte, error) {
+	if !m.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATEUNICODE) {
+		return nil, errors.New("Only unicode is supported")
+	}
+
+	target, user := toUnicode(m.TargetName), toUnicode(m.UserName)
+	workstation := toUnicode("go-ntlmssp")
+
+	ptr := binary.Size(&authenticateMessageFields{})
+	f := authenticateMessageFields{
+		messageHeader:       newMessageHeader(3),
+		NegotiateFlags:      m.NegotiateFlags,
+		LmChallengeResponse: newVarField(&ptr, len(m.LmChallengeResponse)),
+		NtChallengeResponse: newVarField(&ptr, len(m.NtChallengeResponse)),
+		TargetName:          newVarField(&ptr, len(target)),
+		UserName:            newVarField(&ptr, len(user)),
+		Workstation:         newVarField(&ptr, len(workstation)),
+	}
+
+	f.NegotiateFlags.Unset(negotiateFlagNTLMSSPNEGOTIATEVERSION)
+
+	b := bytes.Buffer{}
+	if err := binary.Write(&b, binary.LittleEndian, &f); err != nil {
+		return nil, err
+	}
+	if err := binary.Write(&b, binary.LittleEndian, &m.LmChallengeResponse); err != nil {
+		return nil, err
+	}
+	if err := binary.Write(&b, binary.LittleEndian, &m.NtChallengeResponse); err != nil {
+		return nil, err
+	}
+	if err := binary.Write(&b, binary.LittleEndian, &target); err != nil {
+		return nil, err
+	}
+	if err := binary.Write(&b, binary.LittleEndian, &user); err != nil {
+		return nil, err
+	}
+	if err := binary.Write(&b, binary.LittleEndian, &workstation); err != nil {
+		return nil, err
+	}
+
+	return b.Bytes(), nil
+}
+
+//ProcessChallenge crafts an AUTHENTICATE message in response to the CHALLENGE message
+//that was received from the server
+func ProcessChallenge(challengeMessageData []byte, user, password string) ([]byte, error) {
+	if user == "" && password == "" {
+		return nil, errors.New("Anonymous authentication not supported")
+	}
+
+	var cm challengeMessage
+	if err := cm.UnmarshalBinary(challengeMessageData); err != nil {
+		return nil, err
+	}
+
+	if cm.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATELMKEY) {
+		return nil, errors.New("Only NTLM v2 is supported, but server requested v1 (NTLMSSP_NEGOTIATE_LM_KEY)")
+	}
+	if cm.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATEKEYEXCH) {
+		return nil, errors.New("Key exchange requested but not supported (NTLMSSP_NEGOTIATE_KEY_EXCH)")
+	}
+
+	am := authenicateMessage{
+		UserName:       user,
+		TargetName:     cm.TargetName,
+		NegotiateFlags: cm.NegotiateFlags,
+	}
+
+	timestamp := cm.TargetInfo[avIDMsvAvTimestamp]
+	if timestamp == nil { // no time sent, take current time
+		ft := uint64(time.Now().UnixNano()) / 100
+		ft += 116444736000000000 // add time between unix & windows offset
+		timestamp = make([]byte, 8)
+		binary.LittleEndian.PutUint64(timestamp, ft)
+	}
+
+	clientChallenge := make([]byte, 8)
+	rand.Reader.Read(clientChallenge)
+
+	ntlmV2Hash := getNtlmV2Hash(password, user, cm.TargetName)
+
+	am.NtChallengeResponse = computeNtlmV2Response(ntlmV2Hash,
+		cm.ServerChallenge[:], clientChallenge, timestamp, cm.TargetInfoRaw)
+
+	if cm.TargetInfoRaw == nil {
+		am.LmChallengeResponse = computeLmV2Response(ntlmV2Hash,
+			cm.ServerChallenge[:], clientChallenge)
+	}
+
+	return am.MarshalBinary()
+}
--- a/authheader.go
+++ b/authheader.go
@@ -0,0 +1,33 @@
+package ntlmssp
+
+import (
+	"encoding/base64"
+	"strings"
+)
+
+type authheader string
+
+func (h authheader) IsBasic() bool {
+	return strings.HasPrefix(string(h), "Basic ")
+}
+
+func (h authheader) IsNegotiate() bool {
+	return strings.HasPrefix(string(h), "Negotiate")
+}
+
+func (h authheader) GetData() ([]byte, error) {
+	p := strings.Split(string(h), " ")
+	if len(p) < 2 {
+		return nil, nil
+	}
+	return base64.StdEncoding.DecodeString(string(p[1]))
+}
+
+func (h authheader) GetBasicCreds() (username, password string, err error) {
+	d, err := h.GetData()
+	if err != nil {
+		return "", "", err
+	}
+	parts := strings.SplitN(string(d), ":", 2)
+	return parts[0], parts[1], nil
+}
--- a/avids.go
+++ b/avids.go
@@ -0,0 +1,17 @@
+package ntlmssp
+
+type avID uint16
+
+const (
+	avIDMsvAvEOL avID = iota
+	avIDMsvAvNbComputerName
+	avIDMsvAvNbDomainName
+	avIDMsvAvDNSComputerName
+	avIDMsvAvDNSDomainName
+	avIDMsvAvDNSTreeName
+	avIDMsvAvFlags
+	avIDMsvAvTimestamp
+	avIDMsvAvSingleHost
+	avIDMsvAvTargetName
+	avIDMsvChannelBindings
+)
--- a/challenge_message.go
+++ b/challenge_message.go
@@ -0,0 +1,82 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+)
+
+type challengeMessageFields struct {
+	messageHeader
+	TargetName      varField
+	NegotiateFlags  negotiateFlags
+	ServerChallenge [8]byte
+	_               [8]byte
+	TargetInfo      varField
+}
+
+func (m challengeMessageFields) IsValid() bool {
+	return m.messageHeader.IsValid() && m.MessageType == 2
+}
+
+type challengeMessage struct {
+	challengeMessageFields
+	TargetName    string
+	TargetInfo    map[avID][]byte
+	TargetInfoRaw []byte
+}
+
+func (m *challengeMessage) UnmarshalBinary(data []byte) error {
+	r := bytes.NewReader(data)
+	err := binary.Read(r, binary.LittleEndian, &m.challengeMessageFields)
+	if err != nil {
+		return err
+	}
+	if !m.challengeMessageFields.IsValid() {
+		return fmt.Errorf("Message is not a valid challenge message: %+v", m.challengeMessageFields.messageHeader)
+	}
+
+	if m.challengeMessageFields.TargetName.Len > 0 {
+		m.TargetName, err = m.challengeMessageFields.TargetName.ReadStringFrom(data, m.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATEUNICODE))
+		if err != nil {
+			return err
+		}
+	}
+
+	if m.challengeMessageFields.TargetInfo.Len > 0 {
+		d, err := m.challengeMessageFields.TargetInfo.ReadFrom(data)
+		m.TargetInfoRaw = d
+		if err != nil {
+			return err
+		}
+		m.TargetInfo = make(map[avID][]byte)
+		r := bytes.NewReader(d)
+		for {
+			var id avID
+			var l uint16
+			err = binary.Read(r, binary.LittleEndian, &id)
+			if err != nil {
+				return err
+			}
+			if id == avIDMsvAvEOL {
+				break
+			}
+
+			err = binary.Read(r, binary.LittleEndian, &l)
+			if err != nil {
+				return err
+			}
+			value := make([]byte, l)
+			n, err := r.Read(value)
+			if err != nil {
+				return err
+			}
+			if n != int(l) {
+				return fmt.Errorf("Expected to read %d bytes, got only %d", l, n)
+			}
+			m.TargetInfo[id] = value
+		}
+	}
+
+	return nil
+}
--- a/messageheader.go
+++ b/messageheader.go
@@ -0,0 +1,21 @@
+package ntlmssp
+
+import (
+	"bytes"
+)
+
+var signature = [8]byte{'N', 'T', 'L', 'M', 'S', 'S', 'P', 0}
+
+type messageHeader struct {
+	Signature   [8]byte
+	MessageType uint32
+}
+
+func (h messageHeader) IsValid() bool {
+	return bytes.Equal(h.Signature[:], signature[:]) &&
+		h.MessageType > 0 && h.MessageType < 4
+}
+
+func newMessageHeader(messageType uint32) messageHeader {
+	return messageHeader{signature, messageType}
+}
--- a/negotiate_flags.go
+++ b/negotiate_flags.go
@@ -0,0 +1,44 @@
+package ntlmssp
+
+type negotiateFlags uint32
+
+const (
+	/*A*/ negotiateFlagNTLMSSPNEGOTIATEUNICODE negotiateFlags = 1 << 0
+	/*B*/ negotiateFlagNTLMNEGOTIATEOEM = 1 << 1
+	/*C*/ negotiateFlagNTLMSSPREQUESTTARGET = 1 << 2
+
+	/*D*/ negotiateFlagNTLMSSPNEGOTIATESIGN = 1 << 4
+	/*E*/ negotiateFlagNTLMSSPNEGOTIATESEAL = 1 << 5
+	/*F*/ negotiateFlagNTLMSSPNEGOTIATEDATAGRAM = 1 << 6
+	/*G*/ negotiateFlagNTLMSSPNEGOTIATELMKEY = 1 << 7
+
+	/*H*/ negotiateFlagNTLMSSPNEGOTIATENTLM = 1 << 9
+
+	/*J*/ negotiateFlagANONYMOUS = 1 << 11
+	/*K*/ negotiateFlagNTLMSSPNEGOTIATEOEMDOMAINSUPPLIED = 1 << 12
+	/*L*/ negotiateFlagNTLMSSPNEGOTIATEOEMWORKSTATIONSUPPLIED = 1 << 13
+
+	/*M*/ negotiateFlagNTLMSSPNEGOTIATEALWAYSSIGN = 1 << 15
+	/*N*/ negotiateFlagNTLMSSPTARGETTYPEDOMAIN = 1 << 16
+	/*O*/ negotiateFlagNTLMSSPTARGETTYPESERVER = 1 << 17
+
+	/*P*/ negotiateFlagNTLMSSPNEGOTIATEEXTENDEDSESSIONSECURITY = 1 << 19
+	/*Q*/ negotiateFlagNTLMSSPNEGOTIATEIDENTIFY = 1 << 20
+
+	/*R*/ negotiateFlagNTLMSSPREQUESTNONNTSESSIONKEY = 1 << 22
+	/*S*/ negotiateFlagNTLMSSPNEGOTIATETARGETINFO = 1 << 23
+
+	/*T*/ negotiateFlagNTLMSSPNEGOTIATEVERSION = 1 << 25
+
+	/*U*/ negotiateFlagNTLMSSPNEGOTIATE128 = 1 << 29
+	/*V*/ negotiateFlagNTLMSSPNEGOTIATEKEYEXCH = 1 << 30
+	/*W*/ negotiateFlagNTLMSSPNEGOTIATE56 = 1 << 31
+)
+
+func (field negotiateFlags) Has(flags negotiateFlags) bool {
+	return field&flags == flags
+}
+
+func (field *negotiateFlags) Unset(flags negotiateFlags) {
+	*field = *field ^ (*field & flags)
+}
--- a/negotiate_message.go
+++ b/negotiate_message.go
@@ -0,0 +1,31 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+type negotiateMessageFields struct {
+	messageHeader
+	NegotiateFlags negotiateFlags
+}
+
+//NewNegotiateMessage creates a new NEGOTIATE message with the
+//flags that this package supports.
+func NewNegotiateMessage() []byte {
+	m := negotiateMessageFields{
+		messageHeader: newMessageHeader(1),
+	}
+
+	m.NegotiateFlags = negotiateFlagNTLMSSPREQUESTTARGET |
+		negotiateFlagNTLMSSPNEGOTIATENTLM |
+		negotiateFlagNTLMSSPNEGOTIATEALWAYSSIGN |
+		negotiateFlagNTLMSSPNEGOTIATEUNICODE
+
+	b := bytes.Buffer{}
+	err := binary.Write(&b, binary.LittleEndian, &m)
+	if err != nil {
+		panic(err)
+	}
+	return b.Bytes()
+}
--- a/negotiator.go
+++ b/negotiator.go
@@ -0,0 +1,101 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"encoding/base64"
+	"io/ioutil"
+	"net/http"
+)
+
+//Negotiator is a http.Roundtripper decorator that automatically
+//converts basic authentication to NTLM/Negotiate authentication when appropriate.
+type Negotiator struct{ http.RoundTripper }
+
+//RoundTrip sends the request to the server, handling any authentication
+//re-sends as needed.
+func (l Negotiator) RoundTrip(req *http.Request) (res *http.Response, err error) {
+	body := bytes.Buffer{}
+	_, err = body.ReadFrom(req.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Body.Close()
+	req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
+
+	reqauth := authheader(req.Header.Get("Authorization"))
+	if reqauth.IsBasic() {
+		// first try anonymous, in case the server still finds us
+		// authenticated from previous traffic
+		req.Header.Del("Authorization")
+
+		res, err = l.RoundTripper.RoundTrip(req)
+		if err != nil {
+			return nil, err
+		}
+		if res.StatusCode != 401 {
+			return res, err
+		}
+	}
+
+	resauth := authheader(res.Header.Get("Www-Authenticate"))
+	if !resauth.IsNegotiate() {
+		// Unauthorized, Negotiate not requested, let's try with basic auth
+		res.Body.Close()
+		req.Header.Set("Authorization", string(reqauth))
+		req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
+
+		res, err = l.RoundTripper.RoundTrip(req)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if res.StatusCode == 401 {
+		resauth := authheader(res.Header.Get("Www-Authenticate"))
+		if reqauth.IsBasic() && resauth.IsNegotiate() {
+			// 401 with request:Basic and response:Negotiate
+			res.Body.Close()
+
+			// recycle credentials
+			u, p, err := reqauth.GetBasicCreds()
+			if err != nil {
+				return nil, err
+			}
+
+			// send negotiate
+			negotiateMessage := NewNegotiateMessage()
+			req.Header.Set("Authorization", "Negotiate "+base64.StdEncoding.EncodeToString(negotiateMessage))
+			req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
+
+			res, err = l.RoundTripper.RoundTrip(req)
+			if err != nil {
+				return nil, err
+			}
+
+			// receive challenge?
+			resauth = authheader(res.Header.Get("Www-Authenticate"))
+			challengeMessage, err := resauth.GetData()
+			if err != nil {
+				return nil, err
+			}
+			if !resauth.IsNegotiate() || len(challengeMessage) == 0 {
+				// Negotiation failed, let client deal with response
+				return res, nil
+			}
+			res.Body.Close()
+
+			// send authenticate
+			authenticateMessage, err := ProcessChallenge(challengeMessage, u, p)
+			if err != nil {
+				return nil, err
+			}
+			req.Header.Set("Authorization", "Negotiate "+base64.StdEncoding.EncodeToString(authenticateMessage))
+			req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
+
+			res, err = l.RoundTripper.RoundTrip(req)
+		}
+	}
+
+	return res, err
+}
--- a/nlmp.go
+++ b/nlmp.go
@@ -0,0 +1,51 @@
+// Package ntlmssp provides NTLM/Negotiate authentication over HTTP
+//
+// Protocol details from https://msdn.microsoft.com/en-us/library/cc236621.aspx,
+// implementation hints from http://davenport.sourceforge.net/ntlm.html .
+// This package only implements authentication, no key exchange or encryption. It
+// only supports Unicode (UTF16LE) encoding of protocol strings, no OEM encoding.
+// This package implements NTLMv2.
+package ntlmssp
+
+import (
+	"crypto/hmac"
+	"crypto/md5"
+	"golang.org/x/crypto/md4"
+	"strings"
+)
+
+func getNtlmV2Hash(password, username, target string) []byte {
+	return hmacMd5(getNtlmHash(password), toUnicode(strings.ToUpper(username)+target))
+}
+
+func getNtlmHash(password string) []byte {
+	hash := md4.New()
+	hash.Write(toUnicode(password))
+	return hash.Sum(nil)
+}
+
+func computeNtlmV2Response(ntlmV2Hash, serverChallenge, clientChallenge,
+	timestamp, targetInfo []byte) []byte {
+
+	temp := []byte{1, 1, 0, 0, 0, 0, 0, 0}
+	temp = append(temp, timestamp...)
+	temp = append(temp, clientChallenge...)
+	temp = append(temp, 0, 0, 0, 0)
+	temp = append(temp, targetInfo...)
+	temp = append(temp, 0, 0, 0, 0)
+
+	NTProofStr := hmacMd5(ntlmV2Hash, serverChallenge, temp)
+	return append(NTProofStr, temp...)
+}
+
+func computeLmV2Response(ntlmV2Hash, serverChallenge, clientChallenge []byte) []byte {
+	return append(hmacMd5(ntlmV2Hash, serverChallenge, clientChallenge), clientChallenge...)
+}
+
+func hmacMd5(key []byte, data ...[]byte) []byte {
+	mac := hmac.New(md5.New, key)
+	for _, d := range data {
+		mac.Write(d)
+	}
+	return mac.Sum(nil)
+}
--- a/nlmp_test.go
+++ b/nlmp_test.go
@@ -0,0 +1,71 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"testing"
+)
+
+// test cases from http://davenport.sourceforge.net/ntlm.html
+
+var username = "user"
+var password = "SecREt01"
+var target = "DOMAIN"
+var challenge = []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef}
+
+func TestCalculateNTLMv2Response(t *testing.T) {
+	NTLMv2Hash := getNtlmV2Hash(password, username, target)
+	ClientChallenge := []byte{0xff, 0xff, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44}
+	Time := []byte{0x00, 0x90, 0xd3, 0x36, 0xb7, 0x34, 0xc3, 0x01}
+	targetInfo := []byte{0x02, 0x00, 0x0c, 0x00, 0x44, 0x00, 0x4f, 0x00, 0x4d, 0x00, 0x41, 0x00, 0x49, 0x00, 0x4e, 0x00, 0x01, 0x00, 0x0c, 0x00, 0x53, 0x00, 0x45, 0x00, 0x52, 0x00, 0x56, 0x00, 0x45, 0x00, 0x52, 0x00, 0x04, 0x00, 0x14, 0x00, 0x64, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x69, 0x00, 0x6e, 0x00, 0x2e, 0x00, 0x63, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x03, 0x00, 0x22, 0x00, 0x73, 0x00, 0x65, 0x00, 0x72, 0x00, 0x76, 0x00, 0x65, 0x00, 0x72, 0x00, 0x2e, 0x00, 0x64, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x69, 0x00, 0x6e, 0x00, 0x2e, 0x00, 0x63, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x00, 0x00, 0x00, 0x00}
+
+	v := computeNtlmV2Response(NTLMv2Hash, challenge, ClientChallenge, Time, targetInfo)
+
+	if expected := []byte{
+		0xcb, 0xab, 0xbc, 0xa7, 0x13, 0xeb, 0x79, 0x5d, 0x04, 0xc9, 0x7a, 0xbc, 0x01, 0xee, 0x49, 0x83,
+		0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x90, 0xd3, 0x36, 0xb7, 0x34, 0xc3, 0x01,
+		0xff, 0xff, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x0c, 0x00,
+		0x44, 0x00, 0x4f, 0x00, 0x4d, 0x00, 0x41, 0x00, 0x49, 0x00, 0x4e, 0x00, 0x01, 0x00, 0x0c, 0x00,
+		0x53, 0x00, 0x45, 0x00, 0x52, 0x00, 0x56, 0x00, 0x45, 0x00, 0x52, 0x00, 0x04, 0x00, 0x14, 0x00,
+		0x64, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x69, 0x00, 0x6e, 0x00, 0x2e, 0x00, 0x63, 0x00,
+		0x6f, 0x00, 0x6d, 0x00, 0x03, 0x00, 0x22, 0x00, 0x73, 0x00, 0x65, 0x00, 0x72, 0x00, 0x76, 0x00,
+		0x65, 0x00, 0x72, 0x00, 0x2e, 0x00, 0x64, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x69, 0x00,
+		0x6e, 0x00, 0x2e, 0x00, 0x63, 0x00, 0x6f, 0x00, 0x6d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00,
+	}; !bytes.Equal(v, expected) {
+		t.Fatalf("expected %x, got %x", expected, v)
+	}
+}
+
+func TestCalculateLMv2Response(t *testing.T) {
+	NTLMv2Hash := getNtlmV2Hash(password, username, target)
+	ClientChallenge := []byte{0xff, 0xff, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44}
+
+	v := computeLmV2Response(NTLMv2Hash, challenge, ClientChallenge)
+
+	if expected := []byte{
+		0xd6, 0xe6, 0x15, 0x2e, 0xa2, 0x5d, 0x03, 0xb7, 0xc6, 0xba, 0x66, 0x29, 0xc2, 0xd6, 0xaa, 0xf0, 0xff, 0xff, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44,
+	}; !bytes.Equal(v, expected) {
+		t.Fatalf("expected %x, got %x", expected, v)
+	}
+}
+
+func TestToUnicode(t *testing.T) {
+	v := toUnicode(password)
+	if expected := []byte{0x53, 0x00, 0x65, 0x00, 0x63, 0x00, 0x52, 0x00, 0x45, 0x00, 0x74, 0x00, 0x30, 0x00, 0x31, 0x00}; !bytes.Equal(v, expected) {
+		t.Fatalf("expected %v, got %v", expected, v)
+	}
+}
+
+func TestNTLMhash(t *testing.T) {
+	v := getNtlmHash(password)
+	if expected := []byte{0xcd, 0x06, 0xca, 0x7c, 0x7e, 0x10, 0xc9, 0x9b, 0x1d, 0x33, 0xb7, 0x48, 0x5a, 0x2e, 0xd8, 0x08}; !bytes.Equal(v, expected) {
+		t.Fatalf("expected %v, got %v", expected, v)
+	}
+}
+
+func TestNTLMv2Hash(t *testing.T) {
+	v := getNtlmV2Hash(password, username, target)
+	if expected := []byte{0x04, 0xb8, 0xe0, 0xba, 0x74, 0x28, 0x9c, 0xc5, 0x40, 0x82, 0x6b, 0xab, 0x1d, 0xee, 0x63, 0xae}; !bytes.Equal(v, expected) {
+		t.Fatalf("expected %v, got %v", expected, v)
+	}
+}
--- a/unicode.go
+++ b/unicode.go
@@ -0,0 +1,29 @@
+package ntlmssp
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"unicode/utf16"
+)
+
+// helper func's for dealing with Windows Unicode (UTF16LE)
+
+func fromUnicode(d []byte) (string, error) {
+	if len(d)%2 > 0 {
+		return "", errors.New("Unicode (UTF 16 LE) specified, but uneven data length")
+	}
+	s := make([]uint16, len(d)/2)
+	err := binary.Read(bytes.NewReader(d), binary.LittleEndian, &s)
+	if err != nil {
+		return "", err
+	}
+	return string(utf16.Decode(s)), nil
+}
+
+func toUnicode(s string) []byte {
+	uints := utf16.Encode([]rune(s))
+	b := bytes.Buffer{}
+	binary.Write(&b, binary.LittleEndian, &uints)
+	return b.Bytes()
+}
--- a/varfield.go
+++ b/varfield.go
@@ -0,0 +1,40 @@
+package ntlmssp
+
+import (
+	"errors"
+)
+
+type varField struct {
+	Len          uint16
+	MaxLen       uint16
+	BufferOffset uint32
+}
+
+func (f varField) ReadFrom(buffer []byte) ([]byte, error) {
+	if len(buffer) < int(f.BufferOffset+uint32(f.Len)) {
+		return nil, errors.New("Error reading data, varField extends beyond buffer")
+	}
+	return buffer[f.BufferOffset : f.BufferOffset+uint32(f.Len)], nil
+}
+
+func (f varField) ReadStringFrom(buffer []byte, unicode bool) (string, error) {
+	d, err := f.ReadFrom(buffer)
+	if err != nil {
+		return "", err
+	}
+	if unicode { // UTF-16LE encoding scheme
+		return fromUnicode(d)
+	}
+	// OEM encoding, close enough to ASCII, since no code page is specified
+	return string(d), err
+}
+
+func newVarField(ptr *int, fieldsize int) varField {
+	f := varField{
+		Len:          uint16(fieldsize),
+		MaxLen:       uint16(fieldsize),
+		BufferOffset: uint32(*ptr),
+	}
+	*ptr += fieldsize
+	return f
+}