encrypt.cpp

#include "lib/aes.h"
#include "lib/md5.h"
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include "encrypt.h"
#include "common.h"
#include "log.h"

//static uint64_t seq=1;

static int8_t zero_iv[]={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,   0,0,0,0};//this prog use zero iv,you should make sure first block of data contains a random/nonce data
/****
 * security of zero_iv + nonce first data block
 * https://crypto.stackexchange.com/questions/5421/using-cbc-with-a-fixed-iv-and-a-random-first-plaintext-block
****/

char key[16];//generated from key_string by md5.
/*
TODO

Change md5 to HMAC-md5 if necessary.Change padding to PKCS#7 style if necessary.

Need someone with cryptography knowledge to help review the encryption method.

Change them if necessary(I can do this by myself,if it turns out to be necessary).

github issue:

https://github.com/wangyu-/udp2raw-tunnel/issues/17

*/

unordered_map<int, const char *> auth_mode_tostring = {{auth_none, "none"}, {auth_md5, "md5"}, {auth_crc32, "crc32"},{auth_simple,"simple"}};
unordered_map<int, const char *> cipher_mode_tostring={{cipher_none,"none"},{cipher_aes128cbc,"aes128cbc"},{cipher_xor,"xor"}};

auth_mode_t auth_mode=auth_md5;
cipher_mode_t cipher_mode=cipher_aes128cbc;


/*
 *  this function comes from  http://www.hackersdelight.org/hdcodetxt/crc.c.txt
 */
unsigned int crc32h(unsigned char *message,int len) {
   int i, crc;
   unsigned int byte, c;
   const unsigned int g0 = 0xEDB88320,    g1 = g0>>1,
      g2 = g0>>2, g3 = g0>>3, g4 = g0>>4, g5 = g0>>5,
      g6 = (g0>>6)^g0, g7 = ((g0>>6)^g0)>>1;

   i = 0;
   crc = 0xFFFFFFFF;
   while (i!=len) {    // Get next byte.
	   byte = message[i];
      crc = crc ^ byte;
      c = ((crc<<31>>31) & g7) ^ ((crc<<30>>31) & g6) ^
          ((crc<<29>>31) & g5) ^ ((crc<<28>>31) & g4) ^
          ((crc<<27>>31) & g3) ^ ((crc<<26>>31) & g2) ^
          ((crc<<25>>31) & g1) ^ ((crc<<24>>31) & g0);
      crc = ((unsigned)crc >> 8) ^ c;
      i = i + 1;
   }
   return ~crc;
}

/*
 void sum(const unsigned  char *data,int len,unsigned char*  res) {
   memset(res,0,sizeof(int));
   for(int i=0,j=0;i<len;i++,j++)
   {
	   if(j==4) j=0;
	   res[j]+=data[i];
   }

   return ;
}*/

void simple_hash(unsigned char *str,int len,unsigned char res[8])   //djb2+ sdbm
{
	 u32_t hash = 5381;
     u32_t hash2 = 0;
     int c;
     int i=0;
    while(c = *str++,i++!=len)
    {
        // hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
         hash = ((hash << 5) + hash)^c; /* (hash * 33) ^ c */
         hash2 = c + (hash2 << 6) + (hash2 << 16) - hash2;
    }

     hash=htonl(hash);
     hash2=htonl(hash2);
     memcpy(res,&hash,sizeof(hash));
     memcpy(res+sizeof(hash),&hash2,sizeof(hash2));
 }

int auth_md5_cal(const char *data,char * output,int &len)
{
	memcpy(output,data,len);//TODO inefficient code
	md5((unsigned char *)output,len,(unsigned char *)(output+len));
	len+=16;
	return 0;
}

int auth_crc32_cal(const char *data,char * output,int &len)
{
	memcpy(output,data,len);//TODO inefficient code
	unsigned int  ret=crc32h((unsigned char *)output,len);
	unsigned int  ret_n=htonl(ret);
	memcpy(output+len,&ret_n,sizeof(unsigned int));
	len+=sizeof(unsigned int);
	return 0;
}

int auth_simple_cal(const char *data,char * output,int &len)
{
	//char res[4];
	memcpy(output,data,len);//TODO inefficient code
	simple_hash((unsigned char *)output,len,(unsigned char *)(output+len));
	len+=8;
	return 0;
}
int auth_simple_verify(const char *data,int &len)
{
	if(len<8) return -1;
	unsigned char res[8];
	len-=8;
	simple_hash((unsigned char *)data,len,res);
	if(memcmp(res,data+len,8)!=0)
		return -1;
	return 0;
}


int auth_none_cal(const char *data,char * output,int &len)
{
	memcpy(output,data,len);
	return 0;
}
int auth_md5_verify(const char *data,int &len)
{
	if(len<16)
	{
		mylog(log_trace,"auth_md5_verify len<16\n");
		return -1;
	}
	char md5_res[16];

	md5((unsigned char *)data,len-16,(unsigned char *)md5_res);

	if(memcmp(md5_res,data+len-16,16)!=0)
	{
		mylog(log_trace,"auth_md5_verify md5 check failed\n");
		return -2;
	}
	len-=16;
	return 0;
}
int auth_none_verify(const char *data,int &len)
{
	return 0;
}

int cipher_xor_encrypt(const char * data, char *output,int &len, char *key) {
        int i, j;
        for (i = 0, j = 0; i < len; i++, j++) {
        	if(j==16) j=0;
                output[i] = data[i]^key[j];
        }
        return 0;
}
int cipher_xor_decrypt(const char * data, char *output,int &len, char *key) {
        int i, j;
        //char tmp[buf_len];
        //len=len/16*16+1;
        //AES128_CBC_decrypt_buffer((uint8_t *)tmp, (uint8_t *)input, len, (uint8_t *)key, (uint8_t *)iv);
        //for(i=0;i<len;i++)
        //input[i]=tmp[i];
        for (i = 0, j = 0; i < len; i++, j++) {
        	if(j==16) j=0;
        	output[i] = data[i]^key[j];
        }
        return 0;
}

int padding(char *data ,int &data_len,int padding_num)
{
	int old_len=data_len;
	data_len+=1;
	if(data_len%padding_num!=0)
	{
		data_len= (data_len/padding_num)*padding_num+padding_num;
	}
	data[data_len-1]= (data_len-old_len);
	return 0;
}

int de_padding(const char *data ,int &data_len,int padding_num)
{
	if((uint8_t)data[data_len-1]  >padding_num) return -1;
	data_len-=(uint8_t)data[data_len-1];
	if(data_len<0)
	{
		return -1;
	}
	return 0;
}
int cipher_aes128cbc_encrypt(const char *data,char *output,int &len,char * key)
{
	static int first_time=1;
	if(aes_key_optimize)
	{
		if(first_time==0) key=0;
		else first_time=0;
	}

	char buf[buf_len];
	memcpy(buf,data,len);//TODO inefficient code


	/*
	int ori_len=len;
	len+=2;//length
	if(len%16!=0)
	{
		len= (len/16)*16+16;
	}
	//if(len>max_data_len) return -1;

	buf[len-2]= (unsigned char)( (uint16_t(ori_len))>>8);
	buf[len-1]=(unsigned char)( ((uint16_t(ori_len))<<8)>>8) ;*/
	if(padding(buf,len,16)<0) return -1;

	AES_CBC_encrypt_buffer((unsigned char *)output,(unsigned char *)buf,len,(unsigned char *)key,(unsigned char *)zero_iv);
	return 0;
}
int auth_crc32_verify(const char *data,int &len)
{
	if(len<int(sizeof(unsigned int)))
	{
		mylog(log_debug,"auth_crc32_verify len<%d\n",int(sizeof(unsigned int)));
		return -1;
	}
	unsigned int  ret=crc32h((unsigned char *)data,len-sizeof(unsigned int));
	unsigned int  ret_n=htonl(ret);

	if(memcmp(data+len-sizeof(unsigned int),&ret_n,sizeof(unsigned int))!=0)
	{
		mylog(log_debug,"auth_crc32_verify memcmp fail\n");
		return -1;
	}
	len-=sizeof(unsigned int);
	return 0;
}
int cipher_none_encrypt(const char *data,char *output,int &len,char * key)
{
	memcpy(output,data,len);
	return 0;
}
int cipher_aes128cbc_decrypt(const char *data,char *output,int &len,char * key)
{
	static int first_time=1;
	if(aes_key_optimize)
	{
		if(first_time==0) key=0;
		else first_time=0;
	}
	if(len%16 !=0) {mylog(log_debug,"len%%16!=0\n");return -1;}
	//if(len<0) {mylog(log_debug,"len <0\n");return -1;}
	AES_CBC_decrypt_buffer((unsigned char *)output,(unsigned char *)data,len,(unsigned char *)key,(unsigned char *)zero_iv);
	if(de_padding(output,len,16)<0) return -1;
	return 0;
}

int cipher_none_decrypt(const char *data,char *output,int &len,char * key)
{
	memcpy(output,data,len);
	return 0;
}

int auth_cal(const char *data,char * output,int &len)
{
	mylog(log_trace,"auth:%d\n",auth_mode);
	switch(auth_mode)
	{
	case auth_crc32:return auth_crc32_cal(data, output, len);
	case auth_md5:return auth_md5_cal(data, output, len);
	case auth_simple:return auth_simple_cal(data, output, len);
	case auth_none:return auth_none_cal(data, output, len);
	default:	return auth_md5_cal(data,output,len);//default
	}

}
int auth_verify(const char *data,int &len)
{
	mylog(log_trace,"auth:%d\n",auth_mode);
	switch(auth_mode)
	{
	case auth_crc32:return auth_crc32_verify(data, len);
	case auth_md5:return auth_md5_verify(data, len);
	case auth_simple:return auth_simple_verify(data, len);
	case auth_none:return auth_none_verify(data, len);
	default:	return auth_md5_verify(data,len);//default
	}

}
int cipher_encrypt(const char *data,char *output,int &len,char * key)
{
	mylog(log_trace,"cipher:%d\n",cipher_mode);
	switch(cipher_mode)
	{
	case cipher_aes128cbc:return cipher_aes128cbc_encrypt(data,output,len, key);
	case cipher_xor:return cipher_xor_encrypt(data,output,len, key);
	case cipher_none:return cipher_none_encrypt(data,output,len, key);
	default:return cipher_aes128cbc_encrypt(data,output,len, key);
	}

}
int cipher_decrypt(const char *data,char *output,int &len,char * key)
{
	mylog(log_trace,"cipher:%d\n",cipher_mode);
	switch(cipher_mode)
	{
		case cipher_aes128cbc:return cipher_aes128cbc_decrypt(data,output,len, key);
		case cipher_xor:return cipher_xor_decrypt(data,output,len, key);
		case cipher_none:return cipher_none_decrypt(data,output,len, key);
		default:	return cipher_aes128cbc_decrypt(data,output,len,key);
	}

}


int my_encrypt(const char *data,char *output,int &len,char * key)
{
	if(len<0) {mylog(log_trace,"len<0");return -1;}
	if(len>max_data_len) {mylog(log_warn,"len>max_data_len");return -1;}

	char buf[buf_len];
	char buf2[buf_len];
	memcpy(buf,data,len);
	if(auth_cal(buf,buf2,len)!=0) {mylog(log_debug,"auth_cal failed ");return -1;}
	if(cipher_encrypt(buf2,output,len,key) !=0) {mylog(log_debug,"cipher_encrypt failed ");return -1;}
	return 0;

}

int my_decrypt(const char *data,char *output,int &len,char * key)
{
	if(len<0) return -1;
	if(len>max_data_len) {mylog(log_warn,"len>max_data_len");return -1;}

	if(cipher_decrypt(data,output,len,key) !=0) {mylog(log_debug,"cipher_decrypt failed \n"); return -1;}
	if(auth_verify(output,len)!=0) {mylog(log_debug,"auth_verify failed\n");return -1;}

	return 0;
}

int my_encrypt_pesudo_header(uint8_t *data,uint8_t *output,int &len,uint8_t * key,uint8_t *header,int hlen)
{

	return 0;
}
int my_decrypt_pesudo_header(uint8_t *data,uint8_t *output,int &len,uint8_t * key,uint8_t *header,int hlen)
{
	return 0;
}