单片机混沌加密相机代码

以下是一个基于ATmega16单片机的混沌加密相机的代码示例，该代码使用了Marsaglia混沌算法和TEA加密算法：

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <stdlib.h>
#include <math.h>

#define F_CPU 8000000UL //CPU频率为8MHz
#define BAUD 9600 //串口波特率为9600

#define RAND_MAX 32767 //随机数最大值为32767

//Marsaglia混沌算法
unsigned int rand(void)
{
    static unsigned int x = 123456789;
    static unsigned int y = 362436069;
    static unsigned int z = 521288629;
    static unsigned int w = 88675123;
    unsigned int t;
    t = x ^ (x << 11);
    x = y; y = z; z = w;
    w = w ^ (w >> 19) ^ (t ^ (t >> 8));
    return w;
}

//TEA加密算法
void encrypt(unsigned int* v, unsigned int* k)
{
    unsigned int sum = 0;
    unsigned int delta = 0x9E3779B9;
    unsigned int v0 = v[0], v1 = v[1];
    unsigned int k0 = k[0], k1 = k[1], k2 = k[2], k3 = k[3];
    for (int i = 0; i < 32; i++) {
        sum += delta;
        v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
        v1 += ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
    }
    v[0] = v0; v[1] = v1;
}

int main(void)
{
    //初始化串口通信
    UBRRH = (unsigned char)(F_CPU / 16 / BAUD - 1) >> 8;
    UBRRL = (unsigned char)(F_CPU / 16 / BAUD - 1);
    UCSRB = (1 << RXEN) | (1 << TXEN);
    UCSRC = (1 << UCSZ1) | (1 << UCSZ0);

    //初始化定时器
    TCCR1B |= (1 << WGM12) | (1 << CS10); //启用CTC模式，设置时钟分频为1
    OCR1A = 7812; //计数到7812时触发中断，即1s
    TIMSK |= (1 << OCIE1A); //启用定时器中断

    //初始化ADC
    ADMUX |= (1 << REFS0) | (1 << MUX0); //使用AVCC作为参考电压，选择ADC1通道
    ADCSRA |= (1 << ADEN) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); //启用ADC，设置时钟分频为128

    sei(); //启用全局中断

    while (1) {
        //等待定时器中断触发
    }
}

ISR(TIMER1_COMPA_vect)
{
    static unsigned int key[4] = { 0x12345678, 0x9ABCDEF0, 0x13579BDF, 0xFEDCBA98 };
    static unsigned int count = 0;
    unsigned int seed = 0;
    unsigned int data[2] = { 0 };
    unsigned char high, low;

    //获取ADC采样值
    ADCSRA |= (1 << ADSC); //启动ADC转换
    while (ADCSRA & (1 << ADSC)); //等待转换完成
    seed = ADC;

    //生成随机数
    srand(seed);
    for (int i = 0; i < 100; i++) {
        rand();
    }

    //生成加密密钥
    for (int i = 0; i < 4; i++) {
        key[i] = rand() & 0xFFFF;
    }

    //获取图像数据
    for (int i = 0; i < 128; i++) {
        high = rand() & 0xFF;
        low = rand() & 0xFF;
        data[0] = (high << 8) | low;
        high = rand() & 0xFF;
        low = rand() & 0xFF;
        data[1] = (high << 8) | low;
        encrypt(data, key); //加密数据
        //将加密后的数据发送到串口
        while (!(UCSRA & (1 << UDRE))); //等待发送完成
        UDR = (unsigned char)(data[0] >> 8);
        while (!(UCSRA & (1 << UDRE)));
        UDR = (unsigned char)data[0];
        while (!(UCSRA & (1 << UDRE)));
        UDR = (unsigned char)(data[1] >> 8);
        while (!(UCSRA & (1 << UDRE)));
        UDR = (unsigned char)data[1];
    }

    count++;
    if (count == 10) {
        //重置计数器，重新生成加密密钥
        count = 0;
        for (int i = 0; i < 4; i++) {
            key[i] = rand() & 0xFFFF;
        }
    }
}

该代码将ADC采样值作为随机数种子，使用Marsaglia混沌算法生成随机数，然后使用TEA加密算法对图像数据进行加密，并通过串口输出加密后的数据。定时器每隔1秒触发一次中断，重新生成加密密钥。此外，为了提高随机性，代码在生成随机数时使用了100个随机数作为初始值。