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用C語言來實現DES加密算法(很急)兩天內

DES雖然不難但是挺繁復的,代碼如下,關鍵點都有英文解釋,仔細看。各個函數的功能都可以從函數名看出來。

#include "pch.h"

#include "misc.h"

#include "des.h"

NAMESPACE_BEGIN(CryptoPP)

/* Tables defined in the Data Encryption Standard documents

* Three of these tables, the initial permutation, the final

* permutation and the expansion operator, are regular enough that

* for speed, we hard-code them. They're here for reference only.

* Also, the S and P boxes are used by a separate program, gensp.c,

* to build the combined SP box, Spbox[]. They're also here just

* for reference.

*/

#ifdef notdef

/* initial permutation IP */

static byte ip[] = {

58, 50, 42, 34, 26, 18, 10, 2,

60, 52, 44, 36, 28, 20, 12, 4,

62, 54, 46, 38, 30, 22, 14, 6,

64, 56, 48, 40, 32, 24, 16, 8,

57, 49, 41, 33, 25, 17, 9, 1,

59, 51, 43, 35, 27, 19, 11, 3,

61, 53, 45, 37, 29, 21, 13, 5,

63, 55, 47, 39, 31, 23, 15, 7

};

/* final permutation IP^-1 */

static byte fp[] = {

40, 8, 48, 16, 56, 24, 64, 32,

39, 7, 47, 15, 55, 23, 63, 31,

38, 6, 46, 14, 54, 22, 62, 30,

37, 5, 45, 13, 53, 21, 61, 29,

36, 4, 44, 12, 52, 20, 60, 28,

35, 3, 43, 11, 51, 19, 59, 27,

34, 2, 42, 10, 50, 18, 58, 26,

33, 1, 41, 9, 49, 17, 57, 25

};

/* expansion operation matrix */

static byte ei[] = {

32, 1, 2, 3, 4, 5,

4, 5, 6, 7, 8, 9,

8, 9, 10, 11, 12, 13,

12, 13, 14, 15, 16, 17,

16, 17, 18, 19, 20, 21,

20, 21, 22, 23, 24, 25,

24, 25, 26, 27, 28, 29,

28, 29, 30, 31, 32, 1

};

/* The (in)famous S-boxes */

static byte sbox[8][64] = {

/* S1 */

14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,

0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,

4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,

15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13,

/* S2 */

15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,

3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,

0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,

13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9,

/* S3 */

10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,

13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,

13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,

1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12,

/* S4 */

7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,

13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,

10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,

3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14,

/* S5 */

2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,

14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,

4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,

11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3,

/* S6 */

12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,

10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,

9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,

4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13,

/* S7 */

4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,

13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,

1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,

6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12,

/* S8 */

13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,

1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,

7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,

2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11

};

/* 32-bit permutation function P used on the output of the S-boxes */

static byte p32i[] = {

16, 7, 20, 21,

29, 12, 28, 17,

1, 15, 23, 26,

5, 18, 31, 10,

2, 8, 24, 14,

32, 27, 3, 9,

19, 13, 30, 6,

22, 11, 4, 25

};

#endif

/* permuted choice table (key) */

static const byte pc1[] = {

57, 49, 41, 33, 25, 17, 9,

1, 58, 50, 42, 34, 26, 18,

10, 2, 59, 51, 43, 35, 27,

19, 11, 3, 60, 52, 44, 36,

63, 55, 47, 39, 31, 23, 15,

7, 62, 54, 46, 38, 30, 22,

14, 6, 61, 53, 45, 37, 29,

21, 13, 5, 28, 20, 12, 4

};

/* number left rotations of pc1 */

static const byte totrot[] = {

1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28

};

/* permuted choice key (table) */

static const byte pc2[] = {

14, 17, 11, 24, 1, 5,

3, 28, 15, 6, 21, 10,

23, 19, 12, 4, 26, 8,

16, 7, 27, 20, 13, 2,

41, 52, 31, 37, 47, 55,

30, 40, 51, 45, 33, 48,

44, 49, 39, 56, 34, 53,

46, 42, 50, 36, 29, 32

};

/* End of DES-defined tables */

/* bit 0 is left-most in byte */

static const int bytebit[] = {

0200,0100,040,020,010,04,02,01

};

/* Set key (initialize key schedule array) */

DES::DES(const byte *key, CipherDir dir)

: k(32)

{

SecByteBlock buffer(56+56+8);

byte *const pc1m=buffer; /* place to modify pc1 into */

byte *const pcr=pc1m+56; /* place to rotate pc1 into */

byte *const ks=pcr+56;

register int i,j,l;

int m;

for (j=0; j<56; j++) { /* convert pc1 to bits of key */

l=pc1[j]-1; /* integer bit location */

m = l & 07; /* find bit */

pc1m[j]=(key[l>>3] & /* find which key byte l is in */

bytebit[m]) /* and which bit of that byte */

? 1 : 0; /* and store 1-bit result */

}

for (i=0; i<16; i++) { /* key chunk for each iteration */

memset(ks,0,8); /* Clear key schedule */

for (j=0; j<56; j++) /* rotate pc1 the right amount */

pcr[j] = pc1m[(l=j+totrot[i])<(j<28? 28 : 56) ? l: l-28];

/* rotate left and right halves independently */

for (j=0; j<48; j++){ /* select bits individually */

/* check bit that goes to ks[j] */

if (pcr[pc2[j]-1]){

/* mask it in if it's there */

l= j % 6;

ks[j/6] |= bytebit[l] >> 2;

}

}

/* Now convert to odd/even interleaved form for use in F */

k[2*i] = ((word32)ks[0] << 24)

| ((word32)ks[2] << 16)

| ((word32)ks[4] << 8)

| ((word32)ks[6]);

k[2*i+1] = ((word32)ks[1] << 24)

| ((word32)ks[3] << 16)

| ((word32)ks[5] << 8)

| ((word32)ks[7]);

}

if (dir==DECRYPTION) // reverse key schedule order

for (i=0; i<16; i+=2)

{

std::swap(k[i], k[32-2-i]);

std::swap(k[i+1], k[32-1-i]);

}

}

/* End of C code common to both versions */

/* C code only in portable version */

// Richard Outerbridge's initial permutation algorithm

/*

inline void IPERM(word32 &left, word32 &right)

{

word32 work;

work = ((left >> 4) ^ right) & 0x0f0f0f0f;

right ^= work;

left ^= work << 4;

work = ((left >> 16) ^ right) & 0xffff;

right ^= work;

left ^= work << 16;

work = ((right >> 2) ^ left) & 0x33333333;

left ^= work;

right ^= (work << 2);

work = ((right >> 8) ^ left) & 0xff00ff;

left ^= work;

right ^= (work << 8);

right = rotl(right, 1);

work = (left ^ right) & 0xaaaaaaaa;

left ^= work;

right ^= work;

left = rotl(left, 1);

}

inline void FPERM(word32 &left, word32 &right)

{

word32 work;

right = rotr(right, 1);

work = (left ^ right) & 0xaaaaaaaa;

left ^= work;

right ^= work;

left = rotr(left, 1);

work = ((left >> 8) ^ right) & 0xff00ff;

right ^= work;

left ^= work << 8;

work = ((left >> 2) ^ right) & 0x33333333;

right ^= work;

left ^= work << 2;

work = ((right >> 16) ^ left) & 0xffff;

left ^= work;

right ^= work << 16;

work = ((right >> 4) ^ left) & 0x0f0f0f0f;

left ^= work;

right ^= work << 4;

}

*/

// Wei Dai's modification to Richard Outerbridge's initial permutation

// algorithm, this one is faster if you have access to rotate instructions

// (like in MSVC)

inline void IPERM(word32 &left, word32 &right)

{

word32 work;

right = rotl(right, 4U);

work = (left ^ right) & 0xf0f0f0f0;

left ^= work;

right = rotr(right^work, 20U);

work = (left ^ right) & 0xffff0000;

left ^= work;

right = rotr(right^work, 18U);

work = (left ^ right) & 0x33333333;

left ^= work;

right = rotr(right^work, 6U);

work = (left ^ right) & 0x00ff00ff;

left ^= work;

right = rotl(right^work, 9U);

work = (left ^ right) & 0xaaaaaaaa;

left = rotl(left^work, 1U);

right ^= work;

}

inline void FPERM(word32 &left, word32 &right)

{

word32 work;

right = rotr(right, 1U);

work = (left ^ right) & 0xaaaaaaaa;

right ^= work;

left = rotr(left^work, 9U);

work = (left ^ right) & 0x00ff00ff;

right ^= work;

left = rotl(left^work, 6U);

work = (left ^ right) & 0x33333333;

right ^= work;

left = rotl(left^work, 18U);

work = (left ^ right) & 0xffff0000;

right ^= work;

left = rotl(left^work, 20U);

work = (left ^ right) & 0xf0f0f0f0;

right ^= work;

left = rotr(left^work, 4U);

}

// Encrypt or decrypt a block of data in ECB mode

void DES::ProcessBlock(const byte *inBlock, byte * outBlock) const

{

word32 l,r,work;

#ifdef IS_LITTLE_ENDIAN

l = byteReverse(*(word32 *)inBlock);

r = byteReverse(*(word32 *)(inBlock+4));

#else

l = *(word32 *)inBlock;

r = *(word32 *)(inBlock+4);

#endif

IPERM(l,r);

const word32 *kptr=k;

for (unsigned i=0; i<8; i++)

{

work = rotr(r, 4U) ^ kptr[4*i+0];

l ^= Spbox[6][(work) & 0x3f]

^ Spbox[4][(work >> 8) & 0x3f]

^ Spbox[2][(work >> 16) & 0x3f]

^ Spbox[0][(work >> 24) & 0x3f];

work = r ^ kptr[4*i+1];

l ^= Spbox[7][(work) & 0x3f]

^ Spbox[5][(work >> 8) & 0x3f]

^ Spbox[3][(work >> 16) & 0x3f]

^ Spbox[1][(work >> 24) & 0x3f];

work = rotr(l, 4U) ^ kptr[4*i+2];

r ^= Spbox[6][(work) & 0x3f]

^ Spbox[4][(work >> 8) & 0x3f]

^ Spbox[2][(work >> 16) & 0x3f]

^ Spbox[0][(work >> 24) & 0x3f];

work = l ^ kptr[4*i+3];

r ^= Spbox[7][(work) & 0x3f]

^ Spbox[5][(work >> 8) & 0x3f]

^ Spbox[3][(work >> 16) & 0x3f]

^ Spbox[1][(work >> 24) & 0x3f];

}

FPERM(l,r);

#ifdef IS_LITTLE_ENDIAN

*(word32 *)outBlock = byteReverse(r);

*(word32 *)(outBlock+4) = byteReverse(l);

#else

*(word32 *)outBlock = r;

*(word32 *)(outBlock+4) = l;

#endif

}

void DES_EDE_Encryption::ProcessBlock(byte *inoutBlock) const

{

e.ProcessBlock(inoutBlock);

d.ProcessBlock(inoutBlock);

e.ProcessBlock(inoutBlock);

}

void DES_EDE_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const

{

e.ProcessBlock(inBlock, outBlock);

d.ProcessBlock(outBlock);

e.ProcessBlock(outBlock);

}

void DES_EDE_Decryption::ProcessBlock(byte *inoutBlock) const

{

d.ProcessBlock(inoutBlock);

e.ProcessBlock(inoutBlock);

d.ProcessBlock(inoutBlock);

}

void DES_EDE_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const

{

d.ProcessBlock(inBlock, outBlock);

e.ProcessBlock(outBlock);

d.ProcessBlock(outBlock);

}

void TripleDES_Encryption::ProcessBlock(byte *inoutBlock) const

{

e1.ProcessBlock(inoutBlock);

d.ProcessBlock(inoutBlock);

e2.ProcessBlock(inoutBlock);

}

void TripleDES_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const

{

e1.ProcessBlock(inBlock, outBlock);

d.ProcessBlock(outBlock);

e2.ProcessBlock(outBlock);

}

void TripleDES_Decryption::ProcessBlock(byte *inoutBlock) const

{

d1.ProcessBlock(inoutBlock);

e.ProcessBlock(inoutBlock);

d2.ProcessBlock(inoutBlock);

}

void TripleDES_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const

{

d1.ProcessBlock(inBlock, outBlock);

e.ProcessBlock(outBlock);

d2.ProcessBlock(outBlock);

}

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