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[函数] DES函数 [复制链接]

chdonald

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发表于 2003-11-18 10:10 |只看该作者 |倒序浏览

1、哪里可以下到C代码的DES函数库
2、以下是我找到的一段代码

#define NULL 0
#ifdef LITTLE_ENDIAN
unsigned long byteswap();
#endif
/* Tables defined in the Data Encryption Standard documents */
/* initial permutation IP */
static char 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 char 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
* This is for reference only; it is unused in the code
* as the f() function performs it implicitly for speed
*/
#ifdef notdef
static char 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
};
#endif
/* permuted choice table (key) */
static char 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 char totrot[] = {
1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28
};
/* permuted choice key (table) */
static char 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
};
/* The (in)famous S-boxes */
static char si[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 char 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
};
/* End of DES-defined tables */
/* Lookup tables initialized once only at startup by desinit() */
static long (*sp)[64]; /* Combined S and P boxes */
static char (*iperm)[16][8]; /* Initial and final permutations */
static char (*fperm)[16][8];
/* 8 6-bit subkeys for each of 16 rounds, initialized by setkey() */
static unsigned char (*kn)[8];
/* bit 0 is left-most in byte */
static int bytebit[] = {
0200,0100,040,020,010,04,02,01
};
static int nibblebit[] = {
010,04,02,01
};
static int desmode;
/* Allocate space and initialize DES lookup arrays
* mode == 0: standard Data Encryption Algorithm
* mode == 1: DEA without initial and final permutations for speed
* mode == 2: DEA without permutations and with 128-byte key (completely
* independent subkeys for each round)
*/
desinit(mode)
int mode;
{
char *malloc();
if(sp != NULL){
/* Already initialized */
return 0;
}
desmode = mode;
if((sp = (long (*)[64])malloc(sizeof(long) * 8 * 64)) == NULL){
return -1;
}
spinit();
kn = (unsigned char (*)[8])malloc(sizeof(char) * 8 * 16);
if(kn == NULL){
free((char *)sp);
return -1;
}
if(mode == 1 || mode == 2) /* No permutations */
return 0;
iperm = (char (*)[16][8])malloc(sizeof(char) * 16 * 16 * 8);
if(iperm == NULL){
free((char *)sp);
free((char *)kn);
return -1;
}
perminit(iperm,ip);
fperm = (char (*)[16][8])malloc(sizeof(char) * 16 * 16 * 8);
if(fperm == NULL){
free((char *)sp);
free((char *)kn);
free((char *)iperm);
return -1;
}
perminit(fperm,fp);
return 0;
}
/* Free up storage used by DES */
desdone()
{
if(sp == NULL)
return; /* Already done */
free((char *)sp);
free((char *)kn);
if(iperm != NULL)
free((char *)iperm);
if(fperm != NULL)
free((char *)fperm);
sp = NULL;
iperm = NULL;
fperm = NULL;
kn = NULL;
}
/* Set key (initialize key schedule array) */
setkey(key)
char *key; /* 64 bits (will use only 56) */
{
char pc1m[56]; /* place to modify pc1 into */
char pcr[56]; /* place to rotate pc1 into */
register int i,j,l;
int m;
/* In mode 2, the 128 bytes of subkey are set directly from the
* user's key, allowing him to use completely independent
* subkeys for each round. Note that the user MUST specify a
* full 128 bytes.
*
* I would like to think that this technique gives the NSA a real
* headache, but I'm not THAT naive.
*/
if(desmode == 2){
for(i=0;i<16;i++)
for(j=0;j<8;j++)
kn[i][j] = *key++;
return;
}
/* Clear key schedule */
for (i=0; i<16; i++)
for (j=0; j<8; j++)
kn[i][j]=0;
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 */
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 kn[j] */
if (pcr[pc2[j]-1]){
/* mask it in if it's there */
l= j % 6;
kn[i][j/6] |= bytebit[l] >;>; 2;
}
}
}
}
/* In-place encryption of 64-bit block */
endes(block)
char *block;
{
register int i;
unsigned long work[2]; /* Working data storage */
long tmp;
permute(block,iperm,(char *)work); /* Initial Permutation */
#ifdef LITTLE_ENDIAN
work[0] = byteswap(work[0]);
work[1] = byteswap(work[1]);
#endif
/* Do the 16 rounds */
for (i=0; i<16; i++)
round(i,work);
/* Left/right half swap */
tmp = work[0];
work[0] = work[1];
work[1] = tmp;
#ifdef LITTLE_ENDIAN
work[0] = byteswap(work[0]);
work[1] = byteswap(work[1]);
#endif
permute((char *)work,fperm,block); /* Inverse initial permutation */
}
/* In-place decryption of 64-bit block */
dedes(block)
char *block;
{
register int i;
unsigned long work[2]; /* Working data storage */
long tmp;
permute(block,iperm,(char *)work); /* Initial permutation */
#ifdef LITTLE_ENDIAN
work[0] = byteswap(work[0]);
work[1] = byteswap(work[1]);
#endif
/* Left/right half swap */
tmp = work[0];
work[0] = work[1];
work[1] = tmp;
/* Do the 16 rounds in reverse order */
for (i=15; i >;= 0; i--)
round(i,work);
#ifdef LITTLE_ENDIAN
work[0] = byteswap(work[0]);
work[1] = byteswap(work[1]);
#endif
permute((char *)work,fperm,block); /* Inverse initial permutation */
}
/* Permute inblock with perm */
static
permute(inblock,perm,outblock)
char *inblock, *outblock; /* result into outblock,64 bits */
char perm[16][16][8]; /* 2K bytes defining perm. */
{
register int i,j;
register char *ib, *ob; /* ptr to input or output block */
register char *p, *q;
if(perm == NULL){
/* No permutation, just copy */
for(i=8; i!=0; i--)
*outblock++ = *inblock++;
return;
}
/* Clear output block */
for (i=8, ob = outblock; i != 0; i--)
*ob++ = 0;
ib = inblock;
for (j = 0; j < 16; j += 2, ib++) { /* for each input nibble */
ob = outblock;
p = perm[j][(*ib >;>; 4) & 017];
q = perm[j + 1][*ib & 017];
for (i = 8; i != 0; i--){ /* and each output byte */
*ob++ |= *p++ | *q++; /* OR the masks together*/
}
}
}
/* Do one DES cipher round */
static
round(num,block)
int num; /* i.e. the num-th one */
unsigned long *block;
{
long f();
/* The rounds are numbered from 0 to 15. On even rounds
* the right half is fed to f() and the result exclusive-ORs
* the left half; on odd rounds the reverse is done.
*/
if(num & 1){
block[1] ^= f(block[0],kn[num]);
} else {
block[0] ^= f(block[1],kn[num]);
}
}
/* The nonlinear function f(r,k), the heart of DES */
static
long
f(r,subkey)
unsigned long r; /* 32 bits */
unsigned char subkey[8]; /* 48-bit key for this round */
{
register unsigned long rval,rt;
#ifdef TRACE
unsigned char *cp;
int i;
printf("f(%08lx, %02x %02x %02x %02x %02x %02x %02x %02x) = ",
r,
subkey[0], subkey[1], subkey[2],
subkey[3], subkey[4], subkey[5],
subkey[6], subkey[7]);
#endif
/* Run E(R) ^ K through the combined S & P boxes
* This code takes advantage of a convenient regularity in
* E, namely that each group of 6 bits in E(R) feeding
* a single S-box is a contiguous segment of R.
*/
rt = (r >;>; 1) | ((r & 1) ? 0x80000000 : 0);
rval = 0;
rval |= sp[0][((rt >;>; 26) ^ *subkey++) & 0x3f];
rval |= sp[1][((rt >;>; 22) ^ *subkey++) & 0x3f];
rval |= sp[2][((rt >;>; 18) ^ *subkey++) & 0x3f];
rval |= sp[3][((rt >;>; 14) ^ *subkey++) & 0x3f];
rval |= sp[4][((rt >;>; 10) ^ *subkey++) & 0x3f];
rval |= sp[5][((rt >;>; 6) ^ *subkey++) & 0x3f];
rval |= sp[6][((rt >;>; 2) ^ *subkey++) & 0x3f];
rt = (r << 1) | ((r & 0x80000000) ? 1 : 0);
rval |= sp[7][(rt ^ *subkey) & 0x3f];
#ifdef TRACE
printf(" %08lx\n",rval);
#endif
return rval;
}
/* initialize a perm array */
static
perminit(perm,p)
char perm[16][16][8]; /* 64-bit, either init or final */
char p[64];
{
register int l, j, k;
int i,m;
/* Clear the permutation array */
for (i=0; i<16; i++)
for (j=0; j<16; j++)
for (k=0; k<8; k++)
perm[i][j][k]=0;
for (i=0; i<16; i++) /* each input nibble position */
for (j = 0; j < 16; j++)/* each possible input nibble */
for (k = 0; k < 64; k++)/* each output bit position */
{ l = p[k] - 1; /* where does this bit come from*/
if ((l >;>; 2) != i) /* does it come from input posn?*/
continue; /* if not, bit k is 0 */
if (!(j & nibblebit[l & 3]))
continue; /* any such bit in input? */
m = k & 07; /* which bit is this in the byte*/
perm[i][j][k>;>;3] |= bytebit[m];
}
}
/* Initialize the lookup table for the combined S and P boxes */
static int
spinit()
{
char pbox[32];
int p,i,s,j,rowcol;
long val;
/* Compute pbox, the inverse of p32i.
* This is easier to work with
*/
for(p=0;p<32;p++){
for(i=0;i<32;i++){
if(p32i[i]-1 == p){
pbox[p] = i;
break;
}
}
}
for(s = 0; s < 8; s++){ /* For each S-box */
for(i=0; i<64; i++){ /* For each possible input */
val = 0;
/* The row number is formed from the first and last
* bits; the column number is from the middle 4
*/
rowcol = (i & 32) | ((i & 1) ? 16 : 0) | ((i >;>; 1) & 0xf);
for(j=0;j<4;j++){ /* For each output bit */
if(si[s][rowcol] & (8 >;>; j)){
val |= 1L << (31 - pbox[4*s + j]);
}
}
sp[s][i] = val;
#ifdef DEBUG
printf("sp[%d][%2d] = %08lx\n",s,i,sp[s][i]);
#endif
}
}
}
#ifdef LITTLE_ENDIAN
/* Byte swap a long */
static
unsigned long
byteswap(x)
unsigned long x;
{
register char *cp,tmp;
cp = (char *)&
tmp = cp[3];
cp[3] = cp[0];
cp[0] = tmp;
tmp = cp[2];
cp[2] = cp[1];
cp[1] = tmp;
return x;
}
#endif

复制代码

读起来比较头痛，看了后不知道它提到的3种MODE分别怎么理解？DES一般来说有4种加密模式：ECB CBC CFB OFB，那这里的0-2三种模式和4种加密模式有什么区别呢，哪位大虾帮忙解释下，最好能大概注解下程序，那就感谢不尽了：）

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gadfly

荣誉版主

论坛徽章:: 1

2楼 [报告]

发表于 2003-11-18 16:15 |只看该作者

DES函数

没研究过。

crypt使用des加密的。

openssl也用到了des。

这两个所属的软件包应该包含des算法的源代码。

实战分享：从技术角度谈机器学习入门| 【大话IT】RadonDB低门槛向MySQL集群下战书 | ChinaUnix打赏功能已上线！ | 新一代分布式关系型数据库RadonDB知多少？

sunlan

版主

论坛徽章:: 0

3楼 [报告]

发表于 2003-11-26 09:06 |只看该作者

DES函数

粗略地看了一下，desmode=2应该是指双重DES，除了ECB、CBC之类的分类外，还有单重DES、双重DES、三重DES的区分

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