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发表于 2010-1-19 19:59:57
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tea.cpp
1 #include "tea.h" 5 G% [; R; b" l) {9 y
2 #include <cstring> //for memcpy,memset
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4 using namespace std; 3 O) b I+ f! l3 x7 z
5
1 K4 Q( h! |- |" x/ B# p 6 TEA::TEA(const byte *key, int round /*= 32*/, bool isNetByte /*= false*/) 8 n! B' H8 E) d. `, ^6 d9 s, C6 z
7 :_round(round) 8 @* a( w4 T! k# v$ [
8 ,_isNetByte(isNetByte) { % y7 N2 T% Z. a; N0 p# u- L+ Z
9 if (key != 0)
* K0 U/ ~/ h$ }& g; d10 memcpy(_key, key, 16);
* \& _' {: o( J# ~& ^" Z7 }3 R7 }11 else
- K4 g) o R9 @4 m$ e% ]0 ]& y12 memset(_key, 0, 16); 6 u# d6 e0 ]: A+ o P/ _
13 }
}( s2 k, F" j4 K9 Q+ Q5 b% V$ W14
* f7 v6 E) U4 E* {3 t7 r8 R15 TEA::TEA(const TEA &rhs)
& o- w) g9 q' P6 A0 g5 E R' [: x16 :_round(rhs._round)
8 i' K* [* H# L17 ,_isNetByte(rhs._isNetByte) { - O' R- S D+ D. P
18 memcpy(_key, rhs._key, 16); # P+ v( _" G& E% G
19 } 0 `7 e, v+ U) p
20
& D' y/ Q S& C+ _2 ~' e; h. q8 r21 TEA& TEA::operator=(const TEA &rhs) { ; }3 E4 L( J3 z0 }8 H. a+ c: C
22 if (&rhs != this) {
& r5 V( g3 K7 M, K% |( U23 _round = rhs._round; 2 W( @2 @, }+ g
24 _isNetByte = rhs._isNetByte; : ~0 z1 x2 N1 k8 A% `3 {+ I7 E6 s2 C) H
25 memcpy(_key, rhs._key, 16);
. W/ s9 R$ z7 ` F$ D, g26 }
( [9 P9 i4 W1 x I27 return *this; % Y* k* z$ N% i. X- J
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29 ( }4 a/ l& K T% ^ K; w/ ^
30 void TEA::encrypt(const byte *in, byte *out) {
3 ]4 W, L2 E% p/ P( a' E" t31 encrypt((const ulong*)in, (ulong*)out);
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34 void TEA::decrypt(const byte *in, byte *out) {
4 ^7 f1 N% h8 i* G5 ~* ?35 decrypt((const ulong*)in, (ulong*)out);
! E, A% V, y. z7 H( x# ?5 P36 }
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38 void TEA::encrypt(const ulong *in, ulong *out) {
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40 ulong *k = (ulong*)_key; 1 P. s Y& n& T' D! N$ O5 s
41 register ulong y = ntoh(in[0]); " H. ]$ k }& v7 O
42 register ulong z = ntoh(in[1]); 3 O5 S; ]- Q; `9 u6 E
43 register ulong a = ntoh(k[0]);
9 z7 \! H; W6 L8 k; s3 x44 register ulong b = ntoh(k[1]);
8 e Q$ V: ~3 O( y8 a9 R45 register ulong c = ntoh(k[2]);
* P. G' i% m! g) l4 l0 R) H6 @46 register ulong d = ntoh(k[3]);
, E- c6 J/ o& ?$ s2 t* Q47 register ulong delta = 0x9E3779B9; /* (sqrt(5)-1)/2*2^32 */
; W; g0 ^/ f9 G, W! L; A48 register int round = _round;
0 w; ^) I2 J6 K9 A% \* N49 register ulong sum = 0;
" l+ V7 ^7 O; R' Q50
: {9 D% w$ c7 g# P+ h, B4 I; I51 while (round--) { /* basic cycle start */
: z0 [2 t& H" |( _% H- |* \52 sum += delta; 3 Q/ @% F- u8 y0 K" [
53 y += ((z << 4) + a) ^ (z + sum) ^ ((z >> 5) + b); / v7 f6 c) M+ n5 K/ C& w! `1 l3 J
54 z += ((y << 4) + c) ^ (y + sum) ^ ((y >> 5) + d); 3 J! e% A6 \; T5 l- C
55 } /* end cycle */
9 M0 c$ B! D- B" _- U& r56 out[0] = ntoh(y);
) T5 [2 p6 `$ {+ g3 ~) W- W, _3 j" ]57 out[1] = ntoh(z); E% E! B* ]. p* @
58 }
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60 void TEA::decrypt(const ulong *in, ulong *out) {
) O3 E! _3 g: R) g4 i61 2 p* i5 `& {- e6 X% p1 w* D
62 ulong *k = (ulong*)_key; : Y1 t8 w. t' e9 J% h6 ]( s
63 register ulong y = ntoh(in[0]); 1 f/ H+ ^0 b0 ]- ~5 z7 Y
64 register ulong z = ntoh(in[1]); / f2 m9 [# L, W* U& p9 y
65 register ulong a = ntoh(k[0]); ) h( c# }0 n W% p6 q6 @0 ? v5 Q
66 register ulong b = ntoh(k[1]); 6 A% k" Q; G8 A6 Q0 g$ r
67 register ulong c = ntoh(k[2]);
1 ?% d: L/ V- ^) Y' T3 r. j68 register ulong d = ntoh(k[3]); , n) U! h5 n( x/ S* s) T% s
69 register ulong delta = 0x9E3779B9; /* (sqrt(5)-1)/2*2^32 */
% u4 F: t& r" y70 register int round = _round; ; A( ]0 o: U. o1 [# ~4 x; l) X
71 register ulong sum = 0; 8 L# y' _8 l! _3 K
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73 if (round == 32) # u' E. Z- k- e2 E! {6 `6 K1 H
74 sum = 0xC6EF3720; /* delta << 5*/
# T( s! S$ u( W6 z0 k7 x- p' Z6 m+ Q3 [75 else if (round == 16) 6 Q9 Z: g$ K, Q. J
76 sum = 0xE3779B90; /* delta << 4*/
* x6 Q, r+ z5 J; |+ N" _& F77 else
- a5 Y3 G3 y/ x# {7 ]0 x9 a78 sum = delta << static_cast<int>(logbase(2, round)); m, c2 }0 S8 [, u, H* m9 Z* u
79 8 r) |' T& L9 ~8 b' Y3 J
80 while (round--) { /* basic cycle start */
4 w* V7 w, {6 a& R; ?81 z -= ((y << 4) + c) ^ (y + sum) ^ ((y >> 5) + d); " I0 ~6 N5 g4 \/ n6 S) k, h
82 y -= ((z << 4) + a) ^ (z + sum) ^ ((z >> 5) + b);
/ i6 J! R9 Y* X8 Y; O0 w83 sum -= delta;
, v( ?1 ~7 }! M4 Y84 } /* end cycle */
3 _; F$ Q7 M/ ^% {( Q8 O- i+ G' J85 out[0] = ntoh(y); ) T7 q+ ?( V- J h0 D! s0 ^; ^
86 out[1] = ntoh(z);
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需要说明的是TEA的构造函数:
' Q* |4 _9 F& z6 R' ~TEA(const byte *key, int round = 32, bool isNetByte = false);
$ N9 ` G6 v6 l8 s Q: W& L7 ?( u1.key - 加密或解密用的128-bit(16byte)密钥。 & c C5 v: _ G; }5 T) D
2.round - 加密或解密的轮数,常用的有64,32,16。 * r g2 x& D! K! P3 d$ n/ B- k
3.isNetByte - 用来标记待处理的字节是不是来自网络,为true时在加密/解密前先要转换成本地字节,执行加密/解密,然后再转换回网络字节。偷偷告诉你,QQ就是这样做的!
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5 L( c/ ] B9 ?9 v最后当然少不了测试代码: |
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