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eea2.go
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eea2.go
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package main
import (
"bufio"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/sha256"
"encoding/binary"
"encoding/hex"
"flag"
"fmt"
"github.com/golang/glog"
"io"
"math"
"math/big"
"os"
"strconv"
)
// 根据T规则
// T = COUNT||BEARER||DIRECTION||026||T0
// T[15-0]byte
func make_T(count []byte, bearer byte, direction byte, t0 uint32) []byte {
T := make([]byte, 16)
T[0] = count[0]
T[1] = count[1]
T[2] = count[2]
T[3] = count[3]
T[4] = ((bearer << 1) | (direction & 0xF1)) << 2
// 26 bits,T[4:2bits---8] 为零,golang初始变量已经清零
// 64 bits t0 ,T[0-7]赋值为t0
t0_slice := make([]byte, 4)
binary.BigEndian.PutUint32(t0_slice, t0)
glog.Errorf("% 0X---%d", t0_slice, t0)
copy(T[12:], t0_slice)
glog.Errorf("T%d---% 0X", t0, T)
return T
}
// 使用EEA2算法ID生成S
// KNASenc生成256bits,截断生成128bits
func make_KNASenc_EEA2(kasme []byte) []byte {
s_message := make([]byte, 7)
s_message[0] = 0x15 // FC 密钥推倒标识
s_message[1] = 0x01 // P0
s_message[2] = 0x01 // L0
s_message[3] = 0x00
s_message[4] = 0x02 // P1
s_message[5] = 0x01 // L1
s_message[6] = 0x00
h := hmac.New(sha256.New, kasme)
h.Write(s_message)
// 256bits KNASenc截断高128bits,留低128bits
return (h.Sum(nil))[:128]
}
// 生成密钥块
func aes_ctr_128(T []byte, key []byte) cipher.Stream {
block, _ := aes.NewCipher(key)
stream := cipher.NewCTR(block, T)
return stream
}
func make_NAS_count(nas_overflow uint16, nas_sqn byte) []byte {
nas_count := make([]byte, 4)
nas_count[0] = nas_sqn
nas_overflow_bytes := make([]byte, 2)
binary.BigEndian.PutUint16(nas_overflow_bytes, nas_overflow)
copy(nas_count[1:], nas_overflow_bytes)
return nas_count
}
func eea2_decrypt(nas_overflow uint16, nas_sqn byte, bearer byte, direction byte, kasme []byte,
cipher_txt []byte, cipher_bit_length uint32) []byte {
var bit_128_count_block uint32 = cipher_bit_length / 128
var bit_128_remaining_block uint32 = cipher_bit_length % 128
var bit_remaining_of_byte uint32 = bit_128_remaining_block % 8
glog.Errorf("bit_of_byte:%d", bit_remaining_of_byte)
nas_count := make_NAS_count(nas_overflow, nas_sqn)
KNASenc_eea2 := make_KNASenc_EEA2(kasme)
plain_txt := make([]byte, len(cipher_txt))
//loop for 128bits
var t0_increase uint32
to_incr_big := big.NewInt(0)
one_big := big.NewInt(1)
exp_2_64_big := big.NewInt(0)
exp_2_64_big.Exp(big.NewInt(2), big.NewInt(64), nil)
mod_data := big.NewInt(0)
glog.Errorf("count_block:%d", bit_128_count_block)
for t0_increase < bit_128_count_block {
T := make_T(nas_count, bearer, direction, t0_increase)
stream := aes_ctr_128(T, KNASenc_eea2)
stream.XORKeyStream(plain_txt[t0_increase*16:], cipher_txt[t0_increase*16:(t0_increase+1)*16])
mod_data.Mod(to_incr_big.Add(to_incr_big, one_big), exp_2_64_big)
t0_increase = uint32(mod_data.Uint64())
}
if bit_128_remaining_block != 0 {
// less than 128bits
T_last := make_T(nas_count, bearer, direction, t0_increase)
stream_last := aes_ctr_128(T_last, KNASenc_eea2)
stream_last.XORKeyStream(plain_txt[t0_increase*16:], cipher_txt[t0_increase*16:])
}
glog.Errorf("plain_text:% 0X", plain_txt)
// 截断多余的bit位
remaining_bytes := bit_128_remaining_block / 8
glog.Errorf("bit_128_remain:%d---byte:%d", bit_128_remaining_block, remaining_bytes)
last_byte_index := t0_increase*16 + remaining_bytes
plain_txt[last_byte_index] = (plain_txt[last_byte_index] >> (8 - bit_remaining_of_byte)) << (8 - bit_remaining_of_byte)
glog.Errorf("% 0X", plain_txt)
return plain_txt
}
func eea2_decrypt_simple(count []byte, key []byte, bearer byte, direction byte,
cipher_txt []byte, cipher_bit_length uint32) []byte {
var bit_128_count_block uint32 = cipher_bit_length / 128
var bit_128_remaining_block uint32 = cipher_bit_length % 128
var bit_remaining_of_byte uint32 = bit_128_remaining_block % 8
glog.Errorf("bit_of_byte:%d", bit_remaining_of_byte)
plain_txt := make([]byte, len(cipher_txt))
nas_count := make([]byte, 4)
copy(nas_count, count)
KNASenc_eea2 := make([]byte, 16)
copy(KNASenc_eea2, key)
//loop for 128bits
var t0_increase uint32
to_incr_big := big.NewInt(0)
one_big := big.NewInt(1)
exp_2_64_big := big.NewInt(0)
exp_2_64_big.Exp(big.NewInt(2), big.NewInt(64), nil)
mod_data := big.NewInt(0)
glog.Errorf("count_block:%d", bit_128_count_block)
for t0_increase < bit_128_count_block {
T := make_T(nas_count, bearer, direction, t0_increase)
stream := aes_ctr_128(T, KNASenc_eea2)
stream.XORKeyStream(plain_txt[t0_increase*16:], cipher_txt[t0_increase*16:(t0_increase+1)*16])
mod_data.Mod(to_incr_big.Add(to_incr_big, one_big), exp_2_64_big)
t0_increase = uint32(mod_data.Uint64())
}
if bit_128_remaining_block != 0 {
// less than 128bits
T_last := make_T(nas_count, bearer, direction, t0_increase)
stream_last := aes_ctr_128(T_last, KNASenc_eea2)
stream_last.XORKeyStream(plain_txt[t0_increase*16:], cipher_txt[t0_increase*16:])
}
glog.Errorf("plain_text:% 0X", plain_txt)
// 截断多余的bit位
remaining_bytes := bit_128_remaining_block / 8
glog.Errorf("bit_128_remain:%d---byte:%d", bit_128_remaining_block, remaining_bytes)
last_byte_index := t0_increase*16 + remaining_bytes
plain_txt[last_byte_index] = (plain_txt[last_byte_index] >> (8 - bit_remaining_of_byte)) << (8 - bit_remaining_of_byte)
glog.Errorf("% 0X", plain_txt)
return plain_txt
}
// for input command line
var infile *string = flag.String("i", "infile", "File contains some eea2 paramerters")
func main() {
flag.Parse()
if infile == nil {
fmt.Println("infile = ", *infile, "must be to enter")
return
}
file, err := os.Open(*infile)
if err != nil {
fmt.Println("Failed to open the input file", *infile)
return
}
defer file.Close()
key := make([]byte, 16)
count := make([]byte, 4)
var cipher_txt *[]byte
var bearer byte
var direction byte
var length uint32
//var ciphter_bytes uint32
br := bufio.NewReader(file)
for i := 0; ; i++ {
values, err := br.ReadBytes(';')
if err != nil && err != io.EOF {
panic(err)
}
if err == io.EOF {
break
}
if i == 0 {
// for key
glog.Errorf("key:%v---%d", values, len(values))
temp := values[:len(values)-1]
_, err := hex.Decode(key, temp)
if err != nil {
glog.Error(err)
}
glog.Errorf("%v---%d", key, len(key))
} else if i == 1 {
// for count
glog.Errorf("count:%v---%d", values, len(values))
temp := values[:len(values)-1]
_, err := hex.Decode(count, temp)
if err != nil {
glog.Error(err)
}
glog.Errorf("%v---%d", count, len(count))
} else if i == 2 {
// for bearer
glog.Errorf("bearer:%v---%d", values, len(values))
temp := values[:len(values)-1]
bearer_value, err := strconv.Atoi(string(temp))
if err != nil {
glog.Error(err)
}
bearer = byte(bearer_value)
glog.Errorf("%d", bearer)
} else if i == 3 {
// for direction
glog.Errorf("direction:%v---%d", values, len(values))
temp := values[:len(values)-1]
direc, err := strconv.Atoi(string(temp))
direction = byte(direc)
if err != nil {
glog.Error(err)
}
glog.Errorf("%d", direction)
} else if i == 4 {
// for length
glog.Errorf("length:%v---%d", values, len(values))
temp := values[:len(values)-1]
bit_len, err := strconv.Atoi(string(temp))
length = uint32(bit_len)
if err != nil {
glog.Error(err)
}
glog.Errorf("%d", length)
} else if i == 5 {
// for cipher_txt
glog.Errorf("cipher_txt:%v---%d", values, len(values))
temp := values[:len(values)-1]
cipher_temp := make([]byte, len(temp)/2)
_, err := hex.Decode(cipher_temp, temp)
if err != nil {
glog.Error(err)
}
cipher_txt = &cipher_temp
glog.Errorf("% 0X---%d", *cipher_txt, len(*cipher_txt))
//ciphter_bytes = uint32(len(cipher_txt))
}
} // end for
// for eea2 decryption
ret := eea2_decrypt_simple(count, key, bearer, direction, *cipher_txt, length)
if len(ret) != len(*cipher_txt) {
fmt.Println("EEA2 decryption error")
} else {
fmt.Println("EEA2 decryption success")
}
glog.Flush()
}