技術標籤：汽車電子軟體BootLoader生產力工具加密演算法嵌入式程序升級

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目錄

• 1. 摘要
• 2. 原始碼
• 3. 參考資料

1. 摘要

之前做專案，由於應用程式涉及的演算法屬於公司核心機密，為保證程式碼在程序升級的過程中不被“擷取”，於是，要在程序升級的過程中，對傳輸的檔案進行加密，要用到TEA加密演算法，本文對該演算法做了總結，希望能幫助有加密*需求的小夥伴:)

2. 原始碼

/*
* XXTEA.c
*
* Created on: Feb 27, 2018
* Author: Allen
*/

#include <stdio.h>
#include
 
 <string.h>

#define MX ( ((z>>5)^(y<<2)) + ((y>>3)^(z<<4)) ) ^ ( (sum^y) + (k[(p & 3)^e]^z) )

typedef unsigned int UInt32;
typedef int Int32;
typedef unsigned short int Word16;
typedef unsigned char U8;

U8 XXTEA (UInt32 *v, Int32 n, UInt32 *k);
Word16 bteaTest();
 


/**
* XXTEA, a Tiny Encryption Algorithm
* by David J. Wheeler, Roger M. Needham
*
* code reorganized by PTK.
*
* \param v Pointer to data array.
* \param n Number of entries in data array.
* - when coding positive number
* - when decoding negative number.
* - when 0 just exit with return 1
* \param k Key k[0] - k[3]. 128 bit
*
*/
 


UInt32 KEY[4] = {0};
/*****************************************************************************/
/*
/*****************************************************************************/
U8 XXTEA (UInt32 *v, Int32 n, UInt32 *k)
{
	unsigned long z = v[n-1];
	unsigned long y = v[0];
	unsigned long sum = 0;
	unsigned long DELTA = 0x9e3779b9;
	unsigned long e;

	long p;
	long q;

	if(n > 1) /* Coding Part */
	{
		q = 6 + (52 / n);
		while(q-- > 0)
		{
			sum += DELTA;
			e = (sum >> 2) & 3;
			for(p = 0; p < (n - 1); p++)
			{
				y = v[p+1];
				v[p]+= MX;
				z = v[p];
			}
			y = v[0];
			v[n-1] += MX;
			z = v[n-1];
		}
		return (0);
	}
	else if(n < -1) /* Decoding Part */
	{
		n = -n;	
		q = 6 + (52 / n);
		sum = q * DELTA;
		while(sum != 0)
		{
			e = (sum >> 2) & 3;
			for(p = (n - 1); p > 0; p--)
			{
				z = v[p-1];
				v[p] -= MX;
				y = v[p];
			}
			z = v[n-1];
			v[0] -= MX;
			y = v[0];
			sum -= DELTA;
		}
		return (0);
	}
	return (1); /* Signal n=0 */
}

/*****************************************************************************/
/*
/*****************************************************************************/
#if 1
Word16 bteaTest()
{
	UInt32 key[4] = { 0x01234567, 0x89ABCDEF, 0x01234567, 0x89ABCDEF };
	UInt32 testVectorPlain[4] = { 0x00000000, 0x11111111, 0x22222222, 0x33333333 };
	UInt32 testVectorEncrypted[4]= { 0xa7399503, 0x8b357cd8, 0x56ef7347, 0xa487d28b };
	
	UInt32 buf[4];
	Word16 i;
	#if 1
	memcpy(buf, testVectorPlain, sizeof(buf));
	XXTEA(buf, 4, key);
	
	for (i = 0; i < 4; i++)
	{
		if (buf[i] != testVectorEncrypted[i])
		return 0;
	}
	#endif
	#if 0
	memcpy(buf, testVectorEncrypted, sizeof(buf));
	XXTEA(buf, -4, key);
	
	for (i = 0; i < 4; i++)
	{
		if (buf[i] != testVectorPlain[i])
		return 0;
	}
	#endif
	// ok
	return 1;
}
#endif

int main()
{
	Word16 tmp = bteaTest();
	printf("Encrypted result:%d\r\n", tmp);
	return 0;
}

3. 參考資料

【1】Tiny Encryption Algorithm
【2】tea演算法
【3】Tiny-Encryption-Algorithm
【4】TEA加密演算法的C++實現