#include "extAuth.h"
#include <stdio.h>

#ifdef I_AM_LTE
#define RAND_STR_LEN 6
const unsigned char srcAuth[16]={0x17,0x0d,0x55,0x9f,0xab,0xcc,0x1c,0x8f,0x30,0x0a,0x28,0xda,0x3c,0x91,0x11,0x6d};
const unsigned char randStr[RAND_STR_LEN]={'s','z','5','0','2','8'};
static unsigned char codeRandStr[RAND_STR_LEN];
unsigned char * extGetCodeRandStr(int *outlen){
	*outlen=RAND_STR_LEN;
	return codeRandStr;
}
/*随机生成一个种子
offset,偏移时间*/
static unsigned char extRandSeed(unsigned int offset){
	unsigned char seed;

	srand(getBaseSeconds()+offset);
	seed=rand()/256;
	return seed;
}

/*使用seed1,seed2对长度为srclen的srcStr进行运算加密*/
static void extCodeToRandStrTmp(unsigned char seed1,unsigned char seed2,unsigned char *srcStr, int srclen){
	unsigned int i,j;
	unsigned char newSeed=seed1|seed2|0xa7;

	for(i=0;i<srclen;i++) srcStr[i] ^= seed1;
	for(i=0;i<srclen;i++) if(i%2) srcStr[i] ^= seed2;
	for(i=0;i<srclen;i++) if(i%2==0) srcStr[i] ^= newSeed;
}

/*获取随机串，地址赋予outStr输出，同时输出串长度*/
unsigned char *extGetRandStr(int *outlen){
	unsigned char seed1,seed2;
	unsigned char tmp[RAND_STR_LEN];
	static unsigned int step=0;

	if(outlen<RAND_STR_LEN) return -1;
	memcpy(tmp, randStr, RAND_STR_LEN);
	seed1=extRandSeed(step);
	seed2=extRandSeed(0x1468+step);
	extCodeToRandStrTmp(seed1, seed2,tmp,RAND_STR_LEN);
	memcpy(codeRandStr,tmp,RAND_STR_LEN);
	*outlen=RAND_STR_LEN;
	step += 77;
	return codeRandStr;
}
#endif

/*对长度为targetlen的targetString进行加密，入参还有长度为randlen的随机串*/
void extCodeBuffer(unsigned char *randString, int randlen, unsigned char *targetString, int targetlen){
	int i,j,k;
	unsigned char value;

	//先使用随机串依次对targetString异常运行
	j=0;
	for(i=0;i<targetlen;i++){
		targetString[i] ^= randString[j];
		if(++j>=randlen) j=0;
	}
	//再对targetString的奇数索引字节，与randString的高低4位指向的srcAuth索引字节异常
	j=0;
	for(i=0;i<targetlen;i++){
		if(j%2) k=randStr[j]&0x0F;
		else k=(randStr[j]>>4)&0x0F;
		value=srcAuth[k];
		if(++j>=randlen) j=0;
		if(i%2) targetString[i] ^= value;
	}
}