源码分享-go语言实现的祖冲之ZUC加密算法

源码路径:free5gc/nas/security/zuc

1. zuc.go

package zuc

// ref: https://www.gsma.com/security/wp-content/uploads/2019/05/eea3eia3zucv16.pdf
var sbox0 = [256]byte{
	0x3e, 0x72, 0x5b, 0x47, 0xca, 0xe0, 0x00, 0x33, 0x04, 0xd1, 0x54, 0x98, 0x09, 0xb9, 0x6d, 0xcb,
	0x7b, 0x1b, 0xf9, 0x32, 0xaf, 0x9d, 0x6a, 0xa5, 0xb8, 0x2d, 0xfc, 0x1d, 0x08, 0x53, 0x03, 0x90,
	0x4d, 0x4e, 0x84, 0x99, 0xe4, 0xce, 0xd9, 0x91, 0xdd, 0xb6, 0x85, 0x48, 0x8b, 0x29, 0x6e, 0xac,
	0xcd, 0xc1, 0xf8, 0x1e, 0x73, 0x43, 0x69, 0xc6, 0xb5, 0xbd, 0xfd, 0x39, 0x63, 0x20, 0xd4, 0x38,
	0x76, 0x7d, 0xb2, 0xa7, 0xcf, 0xed, 0x57, 0xc5, 0xf3, 0x2c, 0xbb, 0x14, 0x21, 0x06, 0x55, 0x9b,
	0xe3, 0xef, 0x5e, 0x31, 0x4f, 0x7f, 0x5a, 0xa4, 0x0d, 0x82, 0x51, 0x49, 0x5f, 0xba, 0x58, 0x1c,
	0x4a, 0x16, 0xd5, 0x17, 0xa8, 0x92, 0x24, 0x1f, 0x8c, 0xff, 0xd8, 0xae, 0x2e, 0x01, 0xd3, 0xad,
	0x3b, 0x4b, 0xda, 0x46, 0xeb, 0xc9, 0xde, 0x9a, 0x8f, 0x87, 0xd7, 0x3a, 0x80, 0x6f, 0x2f, 0xc8,
	0xb1, 0xb4, 0x37, 0xf7, 0x0a, 0x22, 0x13, 0x28, 0x7c, 0xcc, 0x3c, 0x89, 0xc7, 0xc3, 0x96, 0x56,
	0x07, 0xbf, 0x7e, 0xf0, 0x0b, 0x2b, 0x97, 0x52, 0x35, 0x41, 0x79, 0x61, 0xa6, 0x4c, 0x10, 0xfe,
	0xbc, 0x26, 0x95, 0x88, 0x8a, 0xb0, 0xa3, 0xfb, 0xc0, 0x18, 0x94, 0xf2, 0xe1, 0xe5, 0xe9, 0x5d,
	0xd0, 0xdc, 0x11, 0x66, 0x64, 0x5c, 0xec, 0x59, 0x42, 0x75, 0x12, 0xf5, 0x74, 0x9c, 0xaa, 0x23,
	0x0e, 0x86, 0xab, 0xbe, 0x2a, 0x02, 0xe7, 0x67, 0xe6, 0x44, 0xa2, 0x6c, 0xc2, 0x93, 0x9f, 0xf1,
	0xf6, 0xfa, 0x36, 0xd2, 0x50, 0x68, 0x9e, 0x62, 0x71, 0x15, 0x3d, 0xd6, 0x40, 0xc4, 0xe2, 0x0f,
	0x8e, 0x83, 0x77, 0x6b, 0x25, 0x05, 0x3f, 0x0c, 0x30, 0xea, 0x70, 0xb7, 0xa1, 0xe8, 0xa9, 0x65,
	0x8d, 0x27, 0x1a, 0xdb, 0x81, 0xb3, 0xa0, 0xf4, 0x45, 0x7a, 0x19, 0xdf, 0xee, 0x78, 0x34, 0x60,
}

var sbox1 = [256]byte{
	0x55, 0xc2, 0x63, 0x71, 0x3b, 0xc8, 0x47, 0x86, 0x9f, 0x3c, 0xda, 0x5b, 0x29, 0xaa, 0xfd, 0x77,
	0x8c, 0xc5, 0x94, 0x0c, 0xa6, 0x1a, 0x13, 0x00, 0xe3, 0xa8, 0x16, 0x72, 0x40, 0xf9, 0xf8, 0x42,
	0x44, 0x26, 0x68, 0x96, 0x81, 0xd9, 0x45, 0x3e, 0x10, 0x76, 0xc6, 0xa7, 0x8b, 0x39, 0x43, 0xe1,
	0x3a, 0xb5, 0x56, 0x2a, 0xc0, 0x6d, 0xb3, 0x05, 0x22, 0x66, 0xbf, 0xdc, 0x0b, 0xfa, 0x62, 0x48,
	0xdd, 0x20, 0x11, 0x06, 0x36, 0xc9, 0xc1, 0xcf, 0xf6, 0x27, 0x52, 0xbb, 0x69, 0xf5, 0xd4, 0x87,
	0x7f, 0x84, 0x4c, 0xd2, 0x9c, 0x57, 0xa4, 0xbc, 0x4f, 0x9a, 0xdf, 0xfe, 0xd6, 0x8d, 0x7a, 0xeb,
	0x2b, 0x53, 0xd8, 0x5c, 0xa1, 0x14, 0x17, 0xfb, 0x23, 0xd5, 0x7d, 0x30, 0x67, 0x73, 0x08, 0x09,
	0xee, 0xb7, 0x70, 0x3f, 0x61, 0xb2, 0x19, 0x8e, 0x4e, 0xe5, 0x4b, 0x93, 0x8f, 0x5d, 0xdb, 0xa9,
	0xad, 0xf1, 0xae, 0x2e, 0xcb, 0x0d, 0xfc, 0xf4, 0x2d, 0x46, 0x6e, 0x1d, 0x97, 0xe8, 0xd1, 0xe9,
	0x4d, 0x37, 0xa5, 0x75, 0x5e, 0x83, 0x9e, 0xab, 0x82, 0x9d, 0xb9, 0x1c, 0xe0, 0xcd, 0x49, 0x89,
	0x01, 0xb6, 0xbd, 0x58, 0x24, 0xa2, 0x5f, 0x38, 0x78, 0x99, 0x15, 0x90, 0x50, 0xb8, 0x95, 0xe4,
	0xd0, 0x91, 0xc7, 0xce, 0xed, 0x0f, 0xb4, 0x6f, 0xa0, 0xcc, 0xf0, 0x02, 0x4a, 0x79, 0xc3, 0xde,
	0xa3, 0xef, 0xea, 0x51, 0xe6, 0x6b, 0x18, 0xec, 0x1b, 0x2c, 0x80, 0xf7, 0x74, 0xe7, 0xff, 0x21,
	0x5a, 0x6a, 0x54, 0x1e, 0x41, 0x31, 0x92, 0x35, 0xc4, 0x33, 0x07, 0x0a, 0xba, 0x7e, 0x0e, 0x34,
	0x88, 0xb1, 0x98, 0x7c, 0xf3, 0x3d, 0x60, 0x6c, 0x7b, 0xca, 0xd3, 0x1f, 0x32, 0x65, 0x04, 0x28,
	0x64, 0xbe, 0x85, 0x9b, 0x2f, 0x59, 0x8a, 0xd7, 0xb0, 0x25, 0xac, 0xaf, 0x12, 0x03, 0xe2, 0xf2,
}

/* the constants D */
var ek_d = [16]uint32{
	0x44D7, 0x26BC, 0x626B, 0x135E, 0x5789, 0x35E2, 0x7135, 0x09AF,
	0x4D78, 0x2F13, 0x6BC4, 0x1AF1, 0x5E26, 0x3C4D, 0x789A, 0x47AC,
}

// Lfsr : linear feedback shift register, the top layer of the zuc algorithm.
//        It has 16 of 31-bit cells (s0, s1,…, s15).
type Lfsr struct {
	s [16]uint32
}

// Br : bit-reorganization, the middle layer of the zuc algorithm.
//      It extracts 128 bits from the cells of the LFSR and forms 4 of 32-bit words. (x0, x1, x2, x3)
type Br struct {
	x [4]uint32
}

// Fsm : nonlinear function, the bottom layer of the zuc algorithm.
//     It has 2 of 32-bit memory cells. (r0, r1)
type Fsm struct {
	r [2]uint32
}

func Zuc(k, iv []byte, wlength uint32) []uint32 {
	lfsr := &Lfsr{}
	br := &Br{}
	f := &Fsm{}

	lfsr.initialization(k, iv, br, f)
	stream := generateKeystream(wlength, lfsr, br, f)
	return stream
}

/* initialize */
func (l *Lfsr) initialization(k, iv []byte, br *Br, f *Fsm) {
	var w uint32
	if l == nil {
		l = &Lfsr{}
	}
	if br == nil {
		br = &Br{}
	}
	if f == nil {
		f = &Fsm{}
	}

	/*  key loading */
	for i := 0; i < 16; i++ {
		l.s[i] = uint32(k[i])<<23 | ek_d[i]<<8 | uint32(iv[i])
	}

	/* set F_R1 and F_R2 to zero */
	f.r[0] = 0
	f.r[1] = 0

	for nCount := 32; nCount > 0; nCount-- {
		br.bitReorganization(*l)
		w = f.nonlinF(*br)
		l.state("InitialisationMode", w>>1)
	}
}

func generateKeystream(wlength uint32, l *Lfsr, br *Br, f *Fsm) []uint32 {
	stream := make([]uint32, int(wlength))
	br.bitReorganization(*l)
	f.nonlinF(*br) /* discard the output of F */
	l.state("WorkMode", uint32(0))

	for i := 0; i < int(wlength); i++ {
		br.bitReorganization(*l)
		stream[i] = f.nonlinF(*br) ^ br.x[3]
		l.state("WorkMode", uint32(0))
	}
	return stream
}

func (l *Lfsr) state(mode string, u uint32) {
	x := []int{0, 4, 10, 13, 15}
	k := []int{8, 20, 21, 17, 15}
	var f uint32 = l.s[0]

	for i, v := range x {
		f += ((l.s[v] << k[i]) | (l.s[v] >> (31 - k[i]))) & 0x7FFFFFFF
		f = (f & 0x7FFFFFFF) + (f >> 31)
	}

	if mode == "InitialisationMode" {
		f += u
		f = (f & 0x7FFFFFFF) + (f >> 31)
	}

	/* update the state */
	for i := 0; i < 15; i++ {
		l.s[i] = l.s[i+1]
	}
	l.s[15] = f
}

func (br *Br) bitReorganization(l Lfsr) {
	br.x[0] = ((l.s[15] & 0x7FFF8000) << 1) | (l.s[14] & 0xFFFF)
	br.x[1] = ((l.s[11] & 0xFFFF) << 16) | (l.s[9] >> 15)
	br.x[2] = ((l.s[7] & 0xFFFF) << 16) | (l.s[5] >> 15)
	br.x[3] = ((l.s[2] & 0xFFFF) << 16) | (l.s[0] >> 15)
}

func (f *Fsm) nonlinF(br Br) uint32 {
	var w, w1, w2, u, v uint32
	w = (br.x[0] ^ f.r[0]) + f.r[1]
	w1 = f.r[0] + br.x[1]
	w2 = f.r[1] ^ br.x[2]
	u = l1((w1 << 16) | (w2 >> 16))
	v = l2((w2 << 16) | (w1 >> 16))
	f.r[0] = makeU32(sbox0[u>>24], sbox1[(u>>16)&0xFF], sbox0[(u>>8)&0xFF], sbox1[u&0xFF])
	f.r[1] = makeU32(sbox0[v>>24], sbox1[(v>>16)&0xFF], sbox0[(v>>8)&0xFF], sbox1[v&0xFF])
	return w
}

func l1(x uint32) uint32 {
	return (x ^ rot(x, 2) ^ rot(x, 10) ^ rot(x, 18) ^ rot(x, 24))
}

func l2(x uint32) uint32 {
	return (x ^ rot(x, 8) ^ rot(x, 14) ^ rot(x, 22) ^ rot(x, 30))
}

func rot(a uint32, k int) uint32 {
	return (a << k) | (a >> (32 - k))
}

func makeU32(a, b, c, d byte) uint32 {
	return (uint32(a) << 24) | (uint32(b) << 16) | (uint32(c) << 8) | uint32(d)
}

2. zuc_test.go

package zuc

import (
	"testing"

	"github.com/stretchr/testify/require"
)

// ref: https://www.gsma.com/security/wp-content/uploads/2019/05/eea3eia3testdatav11.pdf
func TestZuc(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		name   string
		k      []byte
		iv     []byte
		z      []uint32
		length uint32
	}{
		{
			name:   "TestCase1",
			k:      []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
			iv:     []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
			z:      []uint32{0x27bede74, 0x018082da},
			length: 2,
		},
		{
			name:   "TestCase2",
			k:      []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			iv:     []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			z:      []uint32{0x0657cfa0, 0x7096398b},
			length: 2,
		},
		{
			name:   "TestCase3",
			k:      []byte{0x3d, 0x4c, 0x4b, 0xe9, 0x6a, 0x82, 0xfd, 0xae, 0xb5, 0x8f, 0x64, 0x1d, 0xb1, 0x7b, 0x45, 0x5b},
			iv:     []byte{0x84, 0x31, 0x9a, 0xa8, 0xde, 0x69, 0x15, 0xca, 0x1f, 0x6b, 0xda, 0x6b, 0xfb, 0xd8, 0xc7, 0x66},
			z:      []uint32{0x14f1c272, 0x3279c419},
			length: 2,
		},
		{
			name:   "TestCase4",
			k:      []byte{0x4d, 0x32, 0x0b, 0xfa, 0xd4, 0xc2, 0x85, 0xbf, 0xd6, 0xb8, 0xbd, 0x00, 0xf3, 0x9d, 0x8b, 0x41},
			iv:     []byte{0x52, 0x95, 0x9d, 0xab, 0xa0, 0xbf, 0x17, 0x6e, 0xce, 0x2d, 0xc3, 0x15, 0x04, 0x9e, 0xb5, 0x74},
			z:      []uint32{0xed4400e7, 0x0633e5c5},
			length: 2,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			ks := Zuc(tc.k, tc.iv, tc.length)
			require.Equal(t, tc.z, ks)
		})
	}
}