// [M|h]ashes up an IP address and a secret key
// to return a hopefully unique masked IP.
in_addr_t MD5_ip(char *secret, in_addr_t ip)
{
char ipbuf[32];
char obuf[16];
union {
struct bytes {
unsigned char b1;
unsigned char b2;
unsigned char b3;
unsigned char b4;
} bytes;
in_addr_t ip;
} conv;
// MD5sum a secret + the IP address
memset(&ipbuf, 0, sizeof(ipbuf));
snprintf(ipbuf, sizeof(ipbuf), "%lu%s", (unsigned long)ip, secret);
MD5_String2binary(ipbuf, obuf);
// Fold the md5sum to 32 bits, pack the bytes to an in_addr_t
conv.bytes.b1 = obuf[0] ^ obuf[1] ^ obuf[8] ^ obuf[9];
conv.bytes.b2 = obuf[2] ^ obuf[3] ^ obuf[10] ^ obuf[11];
conv.bytes.b3 = obuf[4] ^ obuf[5] ^ obuf[12] ^ obuf[13];
conv.bytes.b4 = obuf[6] ^ obuf[7] ^ obuf[14] ^ obuf[15];
return conv.ip;
}
/** output is the coded character sequence in the character sequence which wants to code string. */
void MD5_String(const char *string, char *output)
{
unsigned char digest[16];
MD5_String2binary(string,digest);
sprintf(output, "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
digest[ 0], digest[ 1], digest[ 2], digest[ 3],
digest[ 4], digest[ 5], digest[ 6], digest[ 7],
digest[ 8], digest[ 9], digest[10], digest[11],
digest[12], digest[13], digest[14], digest[15]);
}
/** output is the coded binary in the character sequence which wants to code string. */
void MD5_Binary(const char *string, unsigned char *output)
{
MD5_String2binary(string,output);
}