加密函数c语言程序加密文件c语言( 三 )

II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
MD5_memset ((POINTER)x, 0, sizeof (x));
}
static void Encode (output, input, len)
unsigned char *output;
UINT4 *input;
unsigned int len;
{
unsigned int i, j;
for (i = 0, j = 0; jlen; i++, j += 4)
{
output[j] = (unsigned char)(input[i]0xff);
output[j+1] = (unsigned char)((input[i]8)0xff);
output[j+2] = (unsigned char)((input[i]16)0xff);
output[j+3] = (unsigned char)((input[i]24)0xff);
}
}
static void Decode (output, input, len)
UINT4 *output;
unsigned char *input;
unsigned int len;
{
unsigned int i, j;
for (i = 0, j = 0; jlen; i++, j += 4)
output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1])8) |(((UINT4)input[j+2])16) | (((UINT4)input[j+3])24);
}
static void MD5_memcpy (output, input, len)
POINTER output;
POINTER input;
unsigned int len;
{
unsigned int i;
for (i = 0; ilen; i++)
output[i] = input[i];
}
static void MD5_memset (output, value, len)
POINTER output;
int value;
unsigned int len;
{
unsigned int i;
for (i = 0; ilen; i++)
((char *)output)[i] = (char)value;
}
#ifndef MD
#define MD 5
#endif
#define TEST_BLOCK_LEN 1000
#define TEST_BLOCK_COUNT 1000
static void MDString PROTO_LIST ((char *));
static void MDPrint PROTO_LIST ((unsigned char [16]));
#define MD_CTX MD5_CTX
#define MDInit MD5Init
#define MDUpdate MD5Update
#define MDFinal MD5Final
int main (int argc, char *argv[])
{
int i;
if (argc1)
{ MDString(argv[1]);
return (0);
}
}
static void MDString (char *string)
{
MD_CTX context;
unsigned char digest[16];
unsigned int len = strlen (string);
MDInit (context);
MDUpdate (context, string, len);
MDFinal (digest, context);
printf ("MD%d (\"%s\") = ", MD, string);
MDPrint (digest);
printf ("\n");
}
static void MDPrint (unsigned char digest[16])
{
unsigned int i;
for (i = 0; i16; i++)
printf ("%02x", digest[i]);
}
用C语言设计程序进行文件的加密这里采用加密函数是：
如果是数组，则不进行加密；
如果是字符，首先将a变成b,b变c,....依次类推，
然后再与加密字符异或
方法/步骤
首先打开VC++6.0
选择文件，新建
选择C++ source file 新建一个空白文档
声明头文件
#includestdio.h
#includestdlib.h
#includestring.h
首先写个加密函数，算法就是简介里说的
void EncryptFile(FILE *sfp,FILE *dfp,char pwd)
{
char ch;
if(sfp==0||dfp==0)
{
printf("ERROR!\n");
return;
}
while((ch=fgetc(sfp))!=EOF)
{
if((ch='a')(ch='z'))
{
ch=(ch-'a'+1)%26+'a';
ch=ch^pwd;
}
if((ch='A')(ch='Z'))
{
ch=(ch-'A'+1)%26+'A';
ch=ch^pwd;
}
fputc(ch,dfp);
}
}
写解密子函数：与加密的过程相反
void DecryptFile(FILE *sfp,FILE *dfp,char pwd)
{
char ch;
while((ch=fgetc(sfp))!=EOF)
{
if((ch='a')(ch='z'))
{
ch=ch^pwd;
ch=(ch-'a'+25)%26+'a';
}
if((ch='A')(ch='Z'))
{
ch=ch^pwd;
ch=(ch-'A'+25)%26+'A';
}
fputc(ch,dfp);

加密函数c语言程序 加密文件c语言( 三 )

加密函数c语言程序加密文件c语言( 三 )