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test: add EAP-AKA' UT
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YuSheng committed Nov 13, 2024
1 parent 243318a commit b428160
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Showing 4 changed files with 589 additions and 91 deletions.
2 changes: 1 addition & 1 deletion eap/eap.go
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Original file line number Diff line number Diff line change
Expand Up @@ -173,7 +173,7 @@ func (eap *EAP) CalcEapAkaPrimeAtMAC(key []byte) ([]byte, error) {
eapAkaPrime := eap.EapTypeData.(*EapAkaPrime)

// Reset AT_MAC
err := eapAkaPrime.InitMac()
err := eapAkaPrime.initMAC()
if err != nil {
return nil, errors.Wrapf(err, "EAP init EAP-AKA' AT_MAC failed")
}
Expand Down
122 changes: 91 additions & 31 deletions eap/eap_aka_prime.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ import (
"fmt"
"io"
"sort"
"unsafe"

"github.com/pkg/errors"
)
Expand Down Expand Up @@ -89,16 +88,22 @@ type EapAkaPrime struct {
attributes map[EapAkaPrimeAttrType]*EapAkaPrimeAttr
}

func NewEapAkaPrime(subType EapAkaSubtype) *EapAkaPrime {
return &EapAkaPrime{
subType: subType,
attributes: make(map[EapAkaPrimeAttrType]*EapAkaPrimeAttr),
}
}

func (eapAkaPrime *EapAkaPrime) Type() EapType { return EapTypeAkaPrime }

func (eapAkaPrime *EapAkaPrime) SubType() EapAkaSubtype { return eapAkaPrime.subType }

func (eapAkaPrime *EapAkaPrime) Init(subType EapAkaSubtype) {
eapAkaPrime.subType = subType
eapAkaPrime.attributes = make(map[EapAkaPrimeAttrType]*EapAkaPrimeAttr)
}

func (eapAkaPrime *EapAkaPrime) SetAttr(attrType EapAkaPrimeAttrType, value []byte) error {
if eapAkaPrime.attributes == nil {
eapAkaPrime.attributes = make(map[EapAkaPrimeAttrType]*EapAkaPrimeAttr)
}

attr := new(EapAkaPrimeAttr)

err := attr.setAttr(attrType, value)
Expand All @@ -111,6 +116,10 @@ func (eapAkaPrime *EapAkaPrime) SetAttr(attrType EapAkaPrimeAttrType, value []by
}

func (eapAkaPrime *EapAkaPrime) GetAttr(attrType EapAkaPrimeAttrType) (EapAkaPrimeAttr, error) {
if eapAkaPrime.attributes == nil {
return EapAkaPrimeAttr{}, errors.Errorf("EAP-AKA' attributes map is nil")
}

for _, attr := range eapAkaPrime.attributes {
if attr.attrType == attrType {
return *attr, nil
Expand All @@ -119,11 +128,6 @@ func (eapAkaPrime *EapAkaPrime) GetAttr(attrType EapAkaPrimeAttrType) (EapAkaPri
return EapAkaPrimeAttr{}, errors.Errorf("EAP-AKA' attribute[%s] is not found", attrType)
}

func (eapAkaPrime *EapAkaPrime) InitMac() error {
zeros := make([]byte, 16)
return eapAkaPrime.SetAttr(AT_MAC, zeros)
}

func (eapAkaPrime *EapAkaPrime) Marshal() ([]byte, error) {
buffer := new(bytes.Buffer)

Expand Down Expand Up @@ -172,6 +176,7 @@ func (eapAkaPrime *EapAkaPrime) Marshal() ([]byte, error) {

func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
var err error
var n int

if len(rawData) < 4 {
return errors.New("EAP-AKA' Unmarshal(): no sufficient bytes to decode the EAP-AKA' type")
Expand All @@ -193,12 +198,15 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
}
eapAkaPrime.subType = EapAkaSubtype(subType)

buf := make([]byte, unsafe.Sizeof(eapAkaPrime.reserved))
_, err = io.ReadFull(bufReader, buf)
buf := make([]byte, EapAkaHeaderReservedLen)
n, err = io.ReadFull(bufReader, buf)
if err != nil {
return errors.Wrapf(err, "EAP-AKA' Unmarshal(): read reserved failed")
}
binary.BigEndian.PutUint16(buf, eapAkaPrime.reserved)
if n != EapAkaHeaderReservedLen {
return errors.New("EAP-AKA' Unmarshal(): incomplete reserved bytes")
}
eapAkaPrime.reserved = binary.BigEndian.Uint16(buf)

if eapAkaPrime.attributes == nil {
eapAkaPrime.attributes = map[EapAkaPrimeAttrType]*EapAkaPrimeAttr{}
Expand Down Expand Up @@ -233,6 +241,10 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
case AT_RAND:
fallthrough
case AT_AUTN:
if attr.length != 5 {
return errors.Errorf("EAP-AKA' Unmarshal(): %s attribute length must be 5", attr.attrType)
}

// In this case, reserved is no meaning
reserved := make([]byte, EapAkaAttrReservedLen)
_, err = io.ReadFull(bufReader, reserved)
Expand All @@ -244,10 +256,22 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
}

valLen := 4*attr.length - EapAkaAttrTypeLen - EapAkaAttrLengthLen - EapAkaAttrReservedLen
if valLen != 16 {
return errors.Errorf("EAP-AKA' Unmarshal(): %s attribute value length must be 16, but got %d",
attr.attrType, valLen,
)
}
attr.value = make([]byte, valLen)
_, err = io.ReadFull(bufReader, attr.value)

n, err = io.ReadFull(bufReader, attr.value)
if err != nil {
if err == io.EOF {
if n != int(valLen) {
return errors.Errorf("EAP-AKA' Unmarshal(): %s attribute value length mismatch, "+
"expect %d bytes but got %d bytes",
attr.attrType, valLen, n,
)
}
break
}
return errors.Wrapf(err, "EAP-AKA' Unmarshal(): read %s attribute/value failed", attr.attrType)
Expand All @@ -256,17 +280,21 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
fallthrough
case AT_RES:
// In this case, reserved will contains the actual length of value
reserved := make([]byte, EapAkaAttrReservedLen) // The unit of reserved is bit
_, err = io.ReadFull(bufReader, reserved)

reserved := make([]byte, EapAkaAttrReservedLen) // The reserved field is the length of the RES in bits
n, err = io.ReadFull(bufReader, reserved)
if err != nil {
if err == io.EOF {
break
}
return errors.Wrapf(err, "EAP-AKA' Unmarshal(): read %s attribute/reserved failed", attr.attrType)
}
if n != EapAkaAttrReservedLen {
return errors.Errorf("EAP-AKA' Unmarshal(): incomplete reserved bytes for %s", attr.attrType)
}
valBitsLen := binary.BigEndian.Uint16(reserved)
attr.reserved = valBitsLen

valBytesLen := valBitsLen / 8
totalLen := uint16(attr.length * 4)
paddingLen := totalLen - valBytesLen - EapAkaAttrTypeLen - EapAkaAttrLengthLen - EapAkaAttrReservedLen

attr.value = make([]byte, valBytesLen)
_, err = io.ReadFull(bufReader, attr.value)
Expand All @@ -276,7 +304,15 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
}
return errors.Wrapf(err, "EAP-AKA' Unmarshal(): read %s attribute/value failed", attr.attrType)
}
// TODO: AT_RES may have padding

// Handle padding
if paddingLen > 0 {
padding := make([]byte, paddingLen)
_, err = io.ReadFull(bufReader, padding)
if err != nil {
return errors.Wrapf(err, "EAP-AKA' Unmarshal(): read %s attribute/padding failed", attr.attrType)
}
}
case AT_KDF:
valLen := 4*attr.length - EapAkaAttrTypeLen - EapAkaAttrLengthLen
attr.value = make([]byte, valLen)
Expand All @@ -289,12 +325,18 @@ func (eapAkaPrime *EapAkaPrime) Unmarshal(rawData []byte) error {
}
}

// Set attribute
eapAkaPrime.attributes[attr.attrType] = attr
}

return nil
}

func (eapAkaPrime *EapAkaPrime) initMAC() error {
zeros := make([]byte, 16)
return eapAkaPrime.SetAttr(AT_MAC, zeros)
}

func (eapAkaPrime *EapAkaPrime) getAttrsKeys() []EapAkaPrimeAttrType {
result := make([]EapAkaPrimeAttrType, 0, len(eapAkaPrime.attributes))

Expand Down Expand Up @@ -413,7 +455,6 @@ func (attr *EapAkaPrimeAttr) setAttr(attrType EapAkaPrimeAttrType, value []byte)
// | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// TODO: Add padding
valBytesLen := len(value)
valBitsLen := valBytesLen * 8

Expand All @@ -423,9 +464,16 @@ func (attr *EapAkaPrimeAttr) setAttr(attrType EapAkaPrimeAttrType, value []byte)
}
}

// Calculate padding bytes needed to make total length multiple of 4
totalLen := EapAkaAttrTypeLen + EapAkaAttrLengthLen + EapAkaAttrReservedLen + valBytesLen
paddingBytes := (4 - (totalLen % 4)) % 4

attr.reserved = uint16(valBitsLen) // The unit of reserved is bit
attr.length = uint8((EapAkaAttrTypeLen + EapAkaAttrTypeLen + EapAkaAttrReservedLen + valBytesLen) / 4)
attr.value = make([]byte, valBytesLen)
attr.length = uint8((totalLen + paddingBytes) / 4)

// Create value slice with padding
paddedLen := valBytesLen + paddingBytes
attr.value = make([]byte, paddedLen)
copy(attr.value, value)
case AT_KDF:
// RFC 5448:
Expand Down Expand Up @@ -475,13 +523,15 @@ func (attr *EapAkaPrimeAttr) setAttr(attrType EapAkaPrimeAttrType, value []byte)
return err
}

func (attr *EapAkaPrimeAttr) GetAttrType() EapAkaPrimeAttrType { return attr.attrType }

func (attr *EapAkaPrimeAttr) GetValue() []byte { return attr.value }

// RFC 9048 - 3.4.1. PRF'
func EapAkaPrimePRF(
ikPrime, ckPrime []byte,
identity string,
) (k_encr, k_aut, k_re, msk, emsk []byte) {
) (k_encr, k_aut, k_re, msk, emsk []byte, err error) {
// PRF'(K,S) = T1 | T2 | T3 | T4 | ...
// where:
// T1 = HMAC-SHA-256 (K, S | 0x01)
Expand All @@ -490,15 +540,20 @@ func EapAkaPrimePRF(
// T4 = HMAC-SHA-256 (K, T3 | S | 0x04)
// ...

key := make([]byte, 0)
if len(ikPrime) == 0 || len(ckPrime) == 0 {
return nil, nil, nil, nil, nil, errors.New("EAP-AKA' PRF: invalid input key length")
}

key := make([]byte, 0, len(ikPrime)+len(ckPrime))
key = append(key, ikPrime...)
key = append(key, ckPrime...)
sBase := []byte("EAP-AKA'" + identity)
sBaseLen := len(sBase)

MK := []byte("") // MK = PRF'(IK'|CK',"EAP-AKA'"|Identity)
prev := []byte("")
MK := make([]byte, 0) // MK = PRF'(IK'|CK',"EAP-AKA'"|Identity)
prev := make([]byte, 0)
const prfRounds = 208/32 + 1

for i := 0; i < prfRounds; i++ {
// Create a new HMAC by defining the hash type and the key (as byte array)
h := hmac.New(sha256.New, key)
Expand All @@ -513,8 +568,9 @@ func EapAkaPrimePRF(
s = append(s, sBaseWithNum...)

// Write Data to it
if _, err := h.Write(s); err != nil {
return nil, nil, nil, nil, nil
_, err = h.Write(s)
if err != nil {
return nil, nil, nil, nil, nil, errors.Wrap(err, "EAP-AKA' PRF: HMAC computation failed")
}

// Get result
Expand All @@ -523,11 +579,15 @@ func EapAkaPrimePRF(
prev = sha
}

if len(MK) < 208 {
return nil, nil, nil, nil, nil, errors.New("EAP-AKA' PRF: insufficient key material generated")
}

k_encr = MK[0:16] // K_encr = MK[0..127]
k_aut = MK[16:48] // K_aut = MK[128..383]
k_re = MK[48:80] // K_re = MK[384..639]
msk = MK[80:144] // MSK = MK[640..1151]
emsk = MK[144:208] // EMSK = MK[1152..1663]

return k_encr, k_aut, k_re, msk, emsk
return k_encr, k_aut, k_re, msk, emsk, nil
}
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