首先，.net中类库中支持各类摘要加解密方式。一般情况下我们将安全分为两类，一类是摘要，一类是加解密。加密解又分为对称与非对称加解密。
在.net体系中，不管是摘要还是加解密，为了统一算法方式，一律都是流方式进行的。不管是MD5摘要还是ADE/DES/TDES/RSA等等。一定要记住的第一条，是流方式进行的！
流——这个概念很多人也不清楚，因为stream的范围还是非常的大的，有网络流responseStream等，基本文本流，IO流等等，在加密时我们使用了一个流叫“加解密流”CryptStream，该流用来实现加解密及摘要算法等等。
那么CryptoStream是个什么流呢？它算是转换流，把一种形式转换成另一种形式，比如把密文转换成明文或把明文换成密文。正常的情况下，我们可以用流写流的方式来实现，比如MemoryStream来换流。当然，也可以把byte[]数组直接写到流中。
流这部分说完了，那么，其实我们如何区别CryptoStream是加密还是解密呢，除了说明之外，还是一个方式，就是看流的方式是读还是写！所以当我看到你的解密流中使用的方式竟然是Write,而不是Read，所以你对加解密方式并没有真正理解。
比如，我们可以转换后的流直接进行ReadToLine即可。
老实说，你这种写法有很大问题——有关stream大部分都是非托管，所以一定要记着Dispose，或Close（Close时会自动调用Dispose)。防止出现错误等内存泄露。
有于加解密流，我们经常一句话，加密方式是Write,解密方式是Read!
#include <stdio.h>#include <memory.h>
#include <time.h>
#include <stdlib.h>
#define PLAIN_FILE_OPEN_ERROR -1
#define KEY_FILE_OPEN_ERROR -2
#define CIPHER_FILE_OPEN_ERROR -3
#define OK 1
typedef char ElemType
/*初始置换表IP*/
int IP_Table[64] = { 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,
56,48,40,32,24,16,8,0,
58,50,42,34,26,18,10,2,
60,52,44,36,28,20,12,4,
62,54,46,38,30,22,14,6}
/*逆初始置换表IP^-1*/
int IP_1_Table[64] = {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,
32,0,40,8,48,16,56,24}
/*扩充置换表E*/
int E_Table[48] = {31, 0, 1, 2, 3, 4,
3, 4, 5, 6, 7, 8,
7, 8,9,10,11,12,
11,12,13,14,15,16,
15,16,17,18,19,20,
19,20,21,22,23,24,
23,24,25,26,27,28,
27,28,29,30,31, 0}
/*置换函数P*/
int P_Table[32] = {15,6,19,20,28,11,27,16,
0,14,22,25,4,17,30,9,
1,7,23,13,31,26,2,8,
18,12,29,5,21,10,3,24}
/*S盒*/
int S[8][4][16] =
/*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}}}
/*置换选择1*/
int PC_1[56] = {56,48,40,32,24,16,8,
0,57,49,41,33,25,17,
9,1,58,50,42,34,26,
18,10,2,59,51,43,35,
62,54,46,38,30,22,14,
6,61,53,45,37,29,21,
13,5,60,52,44,36,28,
20,12,4,27,19,11,3}
/*置换选择2*/
int PC_2[48] = {13,16,10,23,0,4,2,27,
14,5,20,9,22,18,11,3,
25,7,15,6,26,19,12,1,
40,51,30,36,46,54,29,39,
50,44,32,46,43,48,38,55,
33,52,45,41,49,35,28,31}
/*对左移次数的规定*/
int MOVE_TIMES[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}
int ByteToBit(ElemType ch,ElemType bit[8])
int BitToByte(ElemType bit[8],ElemType *ch)
int Char8ToBit64(ElemType ch[8],ElemType bit[64])
int Bit64ToChar8(ElemType bit[64],ElemType ch[8])
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48])
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56])
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48])
int DES_ROL(ElemType data[56], int time)
int DES_IP_Transform(ElemType data[64])
int DES_IP_1_Transform(ElemType data[64])
int DES_E_Transform(ElemType data[48])
int DES_P_Transform(ElemType data[32])
int DES_SBOX(ElemType data[48])
int DES_XOR(ElemType R[48], ElemType L[48],int count)
int DES_Swap(ElemType left[32],ElemType right[32])
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8])
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48], ElemType plainBlock[8])
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile)
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile)
/*字节转换成二进制*/
int ByteToBit(ElemType ch, ElemType bit[8]){
int cnt
for(cnt = 0cnt <8cnt++){
*(bit+cnt) = (ch>>cnt)&1
}
return 0
}
/*二进制转换成字节*/
int BitToByte(ElemType bit[8],ElemType *ch){
int cnt
for(cnt = 0cnt <8cnt++){
*ch |= *(bit + cnt)<<cnt
}
return 0
}
/*将长度为8的字符串转为二进制位串*/
int Char8ToBit64(ElemType ch[8],ElemType bit[64]){
int cnt
for(cnt = 0cnt <8cnt++){
ByteToBit(*(ch+cnt),bit+(cnt<<3))
}
return 0
}
/*将二进制位串转为长度为8的字符串*/
int Bit64ToChar8(ElemType bit[64],ElemType ch[8]){
int cnt
memset(ch,0,8)
for(cnt = 0cnt <8cnt++){
BitToByte(bit+(cnt<<3),ch+cnt)
}
return 0
}
/*生成子密钥*/
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]){
ElemType temp[56]
int cnt
DES_PC1_Transform(key,temp)/*PC1置换*/
for(cnt = 0cnt <16cnt++){/*16轮跌代，产生16个子密钥*/
DES_ROL(temp,MOVE_TIMES[cnt])/*循环左移*/
DES_PC2_Transform(temp,subKeys[cnt])/*PC2置换，产生子密钥*/
}
return 0
}
/*密钥置换1*/
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]){
int cnt
for(cnt = 0cnt <56cnt++){
tempbts[cnt] = key[PC_1[cnt]]
}
return 0
}
/*密钥置换2*/
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]){
int cnt
for(cnt = 0cnt <48cnt++){
tempbts[cnt] = key[PC_2[cnt]]
}
return 0
}
/*循环左移*/
int DES_ROL(ElemType data[56], int time){
ElemType temp[56]
/*保存将要循环移动到右边的位*/
memcpy(temp,data,time)
memcpy(temp+time,data+28,time)
/*前28位移动*/
memcpy(data,data+time,28-time)
memcpy(data+28-time,temp,time)
/*后28位移动*/
memcpy(data+28,data+28+time,28-time)
memcpy(data+56-time,temp+time,time)
return 0
}
/*IP置换*/
int DES_IP_Transform(ElemType data[64]){
int cnt
ElemType temp[64]
for(cnt = 0cnt <64cnt++){
temp[cnt] = data[IP_Table[cnt]]
}
memcpy(data,temp,64)
return 0
}
/*IP逆置换*/
int DES_IP_1_Transform(ElemType data[64]){
int cnt
ElemType temp[64]
for(cnt = 0cnt <64cnt++){
temp[cnt] = data[IP_1_Table[cnt]]
}
memcpy(data,temp,64)
return 0
}
/*扩展置换*/
int DES_E_Transform(ElemType data[48]){
int cnt
ElemType temp[48]
for(cnt = 0cnt <48cnt++){
temp[cnt] = data[E_Table[cnt]]
}
memcpy(data,temp,48)
return 0
}
/*P置换*/
int DES_P_Transform(ElemType data[32]){
int cnt
ElemType temp[32]
for(cnt = 0cnt <32cnt++){
temp[cnt] = data[P_Table[cnt]]
}
memcpy(data,temp,32)
return 0
}
/*异或*/
int DES_XOR(ElemType R[48], ElemType L[48] ,int count){
int cnt
for(cnt = 0cnt <countcnt++){
R[cnt] ^= L[cnt]
}
return 0
}
/*S盒置换*/
int DES_SBOX(ElemType data[48]){
int cnt
int line,row,output
int cur1,cur2
for(cnt = 0cnt <8cnt++){
cur1 = cnt*6
cur2 = cnt<<2
/*计算在S盒中的行与列*/
line = (data[cur1]<<1) + data[cur1+5]
row = (data[cur1+1]<<3) + (data[cur1+2]<<2)
+ (data[cur1+3]<<1) + data[cur1+4]
output = S[cnt][line][row]
/*化为2进制*/
data[cur2] = (output&0X08)>>3
data[cur2+1] = (output&0X04)>>2
data[cur2+2] = (output&0X02)>>1
data[cur2+3] = output&0x01
}
return 0
}
/*交换*/
int DES_Swap(ElemType left[32], ElemType right[32]){
ElemType temp[32]
memcpy(temp,left,32)
memcpy(left,right,32)
memcpy(right,temp,32)
return 0
}
/*加密单个分组*/
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]){
ElemType plainBits[64]
ElemType copyRight[48]
int cnt
Char8ToBit64(plainBlock,plainBits)
/*初始置换（IP置换）*/
DES_IP_Transform(plainBits)
/*16轮迭代*/
for(cnt = 0cnt <16cnt++){
memcpy(copyRight,plainBits+32,32)
/*将右半部分进行扩展置换，从32位扩展到48位*/
DES_E_Transform(copyRight)
/*将右半部分与子密钥进行异或 *** 作*/
DES_XOR(copyRight,subKeys[cnt],48)
/*异或结果进入S盒，输出32位结果*/
DES_SBOX(copyRight)
/*P置换*/
DES_P_Transform(copyRight)
/*将明文左半部分与右半部分进行异或*/
DES_XOR(plainBits,copyRight,32)
if(cnt != 15){
/*最终完成左右部的交换*/
DES_Swap(plainBits,plainBits+32)
}
}
/*逆初始置换（IP^1置换）*/
DES_IP_1_Transform(plainBits)
Bit64ToChar8(plainBits,cipherBlock)
return 0
}
/*解密单个分组*/
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48],ElemType plainBlock[8]){
ElemType cipherBits[64]
ElemType copyRight[48]
int cnt
Char8ToBit64(cipherBlock,cipherBits)
/*初始置换（IP置换）*/
DES_IP_Transform(cipherBits)
/*16轮迭代*/
for(cnt = 15cnt >= 0cnt--){
memcpy(copyRight,cipherBits+32,32)
/*将右半部分进行扩展置换，从32位扩展到48位*/
DES_E_Transform(copyRight)
/*将右半部分与子密钥进行异或 *** 作*/
DES_XOR(copyRight,subKeys[cnt],48)
/*异或结果进入S盒，输出32位结果*/
DES_SBOX(copyRight)
/*P置换*/
DES_P_Transform(copyRight)
/*将明文左半部分与右半部分进行异或*/
DES_XOR(cipherBits,copyRight,32)
if(cnt != 0){
/*最终完成左右部的交换*/
DES_Swap(cipherBits,cipherBits+32)
}
}
/*逆初始置换（IP^1置换）*/
DES_IP_1_Transform(cipherBits)
Bit64ToChar8(cipherBits,plainBlock)
return 0
}
/*加密文件*/
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){
FILE *plain,*cipher
int count
ElemType plainBlock[8],cipherBlock[8],keyBlock[8]
ElemType bKey[64]
ElemType subKeys[16][48]
if((plain = fopen(plainFile,"rb")) == NULL){
return PLAIN_FILE_OPEN_ERROR
}
if((cipher = fopen(cipherFile,"wb")) == NULL){
return CIPHER_FILE_OPEN_ERROR
}
/*设置密钥*/
memcpy(keyBlock,keyStr,8)
/*将密钥转换为二进制流*/
Char8ToBit64(keyBlock,bKey)
/*生成子密钥*/
DES_MakeSubKeys(bKey,subKeys)
while(!feof(plain)){
/*每次读8个字节，并返回成功读取的字节数*/
if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){
DES_EncryptBlock(plainBlock,subKeys,cipherBlock)
fwrite(cipherBlock,sizeof(char),8,cipher)
}
}
if(count){
/*填充*/
memset(plainBlock + count,'\0',7 - count)
/*最后一个字符保存包括最后一个字符在内的所填充的字符数量*/
plainBlock[7] = 8 - count
DES_EncryptBlock(plainBlock,subKeys,cipherBlock)
fwrite(cipherBlock,sizeof(char),8,cipher)
}
fclose(plain)
fclose(cipher)
return OK
}
/*解密文件*/
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){
FILE *plain, *cipher
int count,times = 0
long fileLen
ElemType plainBlock[8],cipherBlock[8],keyBlock[8]
ElemType bKey[64]
ElemType subKeys[16][48]
if((cipher = fopen(cipherFile,"rb")) == NULL){
return CIPHER_FILE_OPEN_ERROR
}
if((plain = fopen(plainFile,"wb")) == NULL){
return PLAIN_FILE_OPEN_ERROR
}
/*设置密钥*/
memcpy(keyBlock,keyStr,8)
/*将密钥转换为二进制流*/
Char8ToBit64(keyBlock,bKey)
/*生成子密钥*/
DES_MakeSubKeys(bKey,subKeys)
/*取文件长度 */
fseek(cipher,0,SEEK_END)/*将文件指针置尾*/
fileLen = ftell(cipher)/*取文件指针当前位置*/
rewind(cipher)/*将文件指针重指向文件头*/
while(1){
/*密文的字节数一定是8的整数倍*/
fread(cipherBlock,sizeof(char),8,cipher)
DES_DecryptBlock(cipherBlock,subKeys,plainBlock)
times += 8
if(times <fileLen){
fwrite(plainBlock,sizeof(char),8,plain)
}
else{
break
}
}
/*判断末尾是否被填充*/
if(plainBlock[7] <8){
for(count = 8 - plainBlock[7]count <7count++){
if(plainBlock[count] != '\0'){
break
}
}
}
if(count == 7){/*有填充*/
fwrite(plainBlock,sizeof(char),8 - plainBlock[7],plain)
}
else{/*无填充*/
fwrite(plainBlock,sizeof(char),8,plain)
}
fclose(plain)
fclose(cipher)
return OK
}
int main()
{
clock_t a,b
a = clock()
DES_Encrypt("1.txt","key.txt","2.txt")
b = clock()
printf("加密消耗%d毫秒\n",b-a)
system("pause")
a = clock()
DES_Decrypt("2.txt","key.txt","3.txt")
b = clock()
printf("解密消耗%d毫秒\n",b-a)
getchar()
return 0
}
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