2018-08-10

HMAC-sha1 加密算法

####c++代码实现

#include <stdlib.h>
#include <stdio.h>
#include <cstring>
#include "hmac_sha1.h"
#define MAX_MESSAGE_LENGTH 4096
/*****************************/
/**** Function Prototypes ****/
/*****************************/

unsigned long int ft(
        int t,
        unsigned long int x,
        unsigned long int y,
        unsigned long int z
);

void sha1   (
        unsigned char *message,
        int message_length,
        unsigned char *digest
);

/**************************/
/* Debug out              */
/**************************/

#ifdef HMAC_DEBUG
debug_out(
            unsigned char *label,
            unsigned char *data,
            int data_length
        )
{
int i,j;
int num_blocks;
int block_remainder;
    num_blocks = data_length / 16;
    block_remainder = data_length % 16;

    printf("%s\n",label);

    for (i=0; i< num_blocks;i++)
    {
        printf("\t");
        for (j=0; j< 16;j++)
        {
            printf("%02x ", data[j + (i*16)]);
        }
        printf("\n");
    }

    if (block_remainder > 0)
    {
        printf("\t");
        for (j=0; j<block_remainder; j++)
        {
            printf("%02x ", data[j+(num_blocks*16)]);
        }
        printf("\n");
    }
}
#endif

/****************************************/
/* sha1()                               */
/* Performs the NIST SHA-1 algorithm    */
/****************************************/

unsigned long int ft(
        int t,
        unsigned long int x,
        unsigned long int y,
        unsigned long int z
)
{
    unsigned long int a,b,c;

    if (t < 20)
    {
        a = x & y;
        b = (~x) & z;
        c = a ^ b;
    }
    else if (t < 40)
    {
        c = x ^ y ^ z;
    }
    else if (t < 60)
    {
        a = x & y;
        b = a ^ (x & z);
        c = b ^ (y & z);
    }
    else if (t < 80)
    {
        c = (x ^ y) ^ z;
    }

    return c;
}

unsigned long int k(int t)
{
    unsigned long int c;

    if (t < 20)
    {
        c = 0x5a827999;
    }
    else if (t < 40)
    {
        c = 0x6ed9eba1;
    }
    else if (t < 60)
    {
        c = 0x8f1bbcdc;
    }
    else if (t < 80)
    {
        c = 0xca62c1d6;
    }

    return c;
}

unsigned long int rotr(int bits, unsigned long int a)
{
    unsigned long int c,d,e,f,g;
    c = (0x0001 << bits)-1;
    d = ~c;

    e = (a & d) >> bits;
    f = (a & c) << (32 - bits);

    g = e | f;

    return (g & 0xffffffff );

}

unsigned long int rotl(int bits, unsigned long int a)
{
    unsigned long int c,d,e,f,g;
    c = (0x0001 << (32-bits))-1;
    d = ~c;

    e = (a & c) << bits;
    f = (a & d) >> (32 - bits);

    g = e | f;

    return (g & 0xffffffff );

}


void sha1   (
        unsigned char *message,
        int message_length,
        unsigned char *digest
)
{
    int i;
    int num_blocks;
    int block_remainder;
    int padded_length;

    unsigned long int l;
    unsigned long int t;
    unsigned long int h[5];
    unsigned long int a,b,c,d,e;
    unsigned long int w[80];
    unsigned long int temp;

#ifdef SHA1_DEBUG
    int x,y;
#endif

    /* Calculate the number of 512 bit blocks */

    padded_length = message_length + 8; /* Add length for l */
    padded_length = padded_length + 1; /* Add the 0x01 bit postfix */

    l = message_length * 8;

    num_blocks = padded_length / 64;
    block_remainder = padded_length % 64;


    if (block_remainder > 0)
    {
        num_blocks++;
    }

    padded_length = padded_length + (64 - block_remainder);

    /* clear the padding field */
    for (i = message_length; i < (num_blocks * 64); i++)
    {
        message[i] = 0x00;
    }

    /* insert b1 padding bit */
    message[message_length] = 0x80;

    /* Insert l */
    message[(num_blocks*64)-1] = (unsigned char)( l        & 0xff);
    message[(num_blocks*64)-2] = (unsigned char)((l >> 8)  & 0xff);
    message[(num_blocks*64)-3] = (unsigned char)((l >> 16) & 0xff);
    message[(num_blocks*64)-4] = (unsigned char)((l >> 24) & 0xff);

    /* Set initial hash state */
    h[0] = 0x67452301;
    h[1] = 0xefcdab89;
    h[2] = 0x98badcfe;
    h[3] = 0x10325476;
    h[4] = 0xc3d2e1f0;

#ifdef SHA1_DEBUG
    printf("INITIAL message_length = %d\n", message_length);
    printf("INITIAL padded_length = %d\n", padded_length);
    printf("INITIAL num_blocks = %d\n", num_blocks);

        for (x=0;x<num_blocks; x++)
        {
            printf("\t\t");
            for (y=0; y<16;y++)
            {
                printf("%02x ",message[y + (x*64)]);
            }
            printf("\n");
            printf("\t\t");
            for (y=0; y<16;y++)
            {
                printf("%02x ",message[16 + y + (x*64)]);
            }
            printf("\n");
            printf("\t\t");
            for (y=0; y<16;y++)
            {
                printf("%02x ",message[32 + y + (x*64)]);
            }
            printf("\n");
            printf("\t\t");
            for (y=0; y<16;y++)
            {
                printf("%02x ",message[48 + y + (x*64)]);
            }
            printf("\n");
        }

#endif

    for (i = 0; i < num_blocks; i++)
    {
        /* Prepare the message schedule */
        for (t=0; t < 80; t++)
        {
            if (t < 16)
            {
                w[t]  = (256*256*256) * message[(i*64)+(t*4)];
                w[t] += (256*256    ) * message[(i*64)+(t*4) + 1];
                w[t] += (256        ) * message[(i*64)+(t*4) + 2];
                w[t] +=                 message[(i*64)+(t*4) + 3];
            }
            else if (t < 80)
            {
                w[t] = rotl(1,(w[t-3] ^ w[t-8] ^ w[t-14] ^ w[t-16]));
            }
        }

#ifdef SHA1_DEBUG
        printf("\tW(0) = %08lX \t W(9)  = %08lX \n", w[0], w[8]);
        printf("\tW(1) = %08lX \t W(10) = %08lX \n", w[1], w[9]);
        printf("\tW(2) = %08lX \t W(11) = %08lX \n", w[2], w[10]);
        printf("\tW(3) = %08lX \t W(12) = %08lX \n", w[3], w[11]);
        printf("\tW(4) = %08lX \t W(13) = %08lX \n", w[4], w[12]);
        printf("\tW(5) = %08lX \t W(14) = %08lX \n", w[5], w[13]);
        printf("\tW(6) = %08lX \t W(15) = %08lX \n", w[6], w[14]);
        printf("\tW(7) = %08lX \t W(16) = %08lX \n\n", w[7], w[15]);

#endif
        /* Initialize the five working variables */
        a = h[0];
        b = h[1];
        c = h[2];
        d = h[3];
        e = h[4];

        /* iterate a-e 80 times */

        for (t = 0; t < 80; t++)
        {
            temp = (rotl(5,a) + ft(t,b,c,d)) & 0xffffffff;
            temp = (temp + e) & 0xffffffff;
            temp = (temp + k(t)) & 0xffffffff;
            temp = (temp + w[t]) & 0xffffffff;
            e = d;
            d = c;
            c = rotl(30,b);
            b = a;
            a = temp;
#ifdef SHA1_DEBUG
            printf("t = %2ld\t %08lx, %08lx, %08lx, %08lx, %08lx\n", t,a,b,c,d,e);
#endif

        }

        /* compute the ith intermediate hash value */
#ifdef SHA1_DEBUG
        printf("  +   \t %08lx, %08lx, %08lx, %08lx, %08lx\n", h[0],h[1],h[2],h[3],h[4]);
#endif
        h[0] = (a + h[0]) & 0xffffffff;
        h[1] = (b + h[1]) & 0xffffffff;
        h[2] = (c + h[2]) & 0xffffffff;
        h[3] = (d + h[3]) & 0xffffffff;
        h[4] = (e + h[4]) & 0xffffffff;

#ifdef SHA1_DEBUG
        printf("  =   \t %08lx, %08lx, %08lx, %08lx, %08lx\n", h[0],h[1],h[2],h[3],h[4]);
#endif

    }

    digest[3]  = (unsigned char) ( h[0]       & 0xff);
    digest[2]  = (unsigned char) ((h[0] >> 8) & 0xff);
    digest[1]  = (unsigned char) ((h[0] >> 16) & 0xff);
    digest[0]  = (unsigned char) ((h[0] >> 24) & 0xff);

    digest[7]  = (unsigned char) ( h[1]       & 0xff);
    digest[6]  = (unsigned char) ((h[1] >> 8) & 0xff);
    digest[5]  = (unsigned char) ((h[1] >> 16) & 0xff);
    digest[4]  = (unsigned char) ((h[1] >> 24) & 0xff);

    digest[11]  = (unsigned char) ( h[2]       & 0xff);
    digest[10]  = (unsigned char) ((h[2] >> 8) & 0xff);
    digest[9] = (unsigned char) ((h[2] >> 16) & 0xff);
    digest[8] = (unsigned char) ((h[2] >> 24) & 0xff);

    digest[15] = (unsigned char) ( h[3]       & 0xff);
    digest[14] = (unsigned char) ((h[3] >> 8) & 0xff);
    digest[13] = (unsigned char) ((h[3] >> 16) & 0xff);
    digest[12] = (unsigned char) ((h[3] >> 24) & 0xff);

    digest[19] = (unsigned char) ( h[4]       & 0xff);
    digest[18] = (unsigned char) ((h[4] >> 8) & 0xff);
    digest[17] = (unsigned char) ((h[4] >> 16) & 0xff);
    digest[16] = (unsigned char) ((h[4] >> 24) & 0xff);

}

/******************************************************/
/* hmac-sha1()                                        */
/* Performs the hmac-sha1 keyed secure hash algorithm */
/******************************************************/

void hmac_sha1(
        unsigned char *key,
        int key_length,
        unsigned char *data,
        int data_length,
        unsigned char *digest
)

{
    int b = 64; /* blocksize */
    unsigned char ipad = 0x36;

    unsigned char opad = 0x5c;

    unsigned char k0[64];
    unsigned char k0xorIpad[64];
    unsigned char step7data[64];
    unsigned char step5data[MAX_MESSAGE_LENGTH+128];
    unsigned char step8data[64+20];
    int i;

    for (i=0; i<64; i++)
    {
        k0[i] = 0x00;
    }



    if (key_length != b)    /* Step 1 */
    {
        /* Step 2 */
        if (key_length > b)
        {
            sha1(key, key_length, digest);
            for (i=0;i<20;i++)
            {
                k0[i]=digest[i];
            }
        }
        else if (key_length < b)  /* Step 3 */
        {
            for (i=0; i<key_length; i++)
            {
                k0[i] = key[i];
            }
        }
    }
    else
    {
        for (i=0;i<b;i++)
        {
            k0[i] = key[i];
        }
    }
#ifdef HMAC_DEBUG
    debug_out("k0",k0,64);
#endif
    /* Step 4 */
    for (i=0; i<64; i++)
    {
        k0xorIpad[i] = k0[i] ^ ipad;
    }
#ifdef HMAC_DEBUG
    debug_out("k0 xor ipad",k0xorIpad,64);
#endif
    /* Step 5 */
    for (i=0; i<64; i++)
    {
        step5data[i] = k0xorIpad[i];
    }
    for (i=0;i<data_length;i++)
    {
        step5data[i+64] = data[i];
    }
#ifdef HMAC_DEBUG
    debug_out("(k0 xor ipad) || text",step5data,data_length+64);
#endif

    /* Step 6 */
    sha1(step5data, data_length+b, digest);

#ifdef HMAC_DEBUG
    debug_out("Hash((k0 xor ipad) || text)",digest,20);
#endif

    /* Step 7 */
    for (i=0; i<64; i++)
    {
        step7data[i] = k0[i] ^ opad;
    }

#ifdef HMAC_DEBUG
    debug_out("(k0 xor opad)",step7data,64);
#endif

    /* Step 8 */
    for (i=0;i<64;i++)
    {
        step8data[i] = step7data[i];
    }
    for (i=0;i<20;i++)
    {
        step8data[i+64] = digest[i];
    }

#ifdef HMAC_DEBUG
    debug_out("(k0 xor opad) || Hash((k0 xor ipad) || text)",step8data,20+64);
#endif

    /* Step 9 */
    sha1(step8data, b+20, digest);

#ifdef HMAC_DEBUG
    debug_out("HASH((k0 xor opad) || Hash((k0 xor ipad) || text))",digest,20);
#endif
}

####原理

#####hmac（hashing message authentication code）信息认证码，一种计算认证码的算法，

输入：secret，message
输出：byte[];
简单步骤：hash(secret ^ out , hash(serret ^ in , message )) ;
- new char in 0x36 ;new char out 0x5c
- 将secret跟in异或之后加入message，结果保存为message1
- 将message1做hash运算（sha1），结果保存为item1
- 将secret跟out异或之后加入item1，结果保存为message2；
- 将message2做hash运算（sha1），结果return；

#####sha1 一种hash算法，在hmac算法过程中会用到

输入：message，messageLength
输出：digest（160位byte）
步骤：https://www.cnblogs.com/FlyingBread/archive/2007/01/02/610206.html

ps：hmac-sha1之后获取的20位byte

####作用

hmac主要应用在身份验证中，它的使用方法是这样的：　

客户端发出登录请求（假设是浏览器的GET请求）　　
服务器返回一个随机值，并在会话中记录这个随机值　　
客户端将该随机值作为密钥，用户密码进行hmac运算，然后提交给服务器　　
服务器读取用户数据库中的用户密码和步骤2中发送的随机值做与客户端一样的hmac运算，然后与用户发送的结果比较，如果结果一致则验证用户合法。

在这个过程中，可能遭到安全攻击的是服务器发送的随机值和用户发送的hmac结果，而对于截获 了这两个值的黑客而言这两个值是没有意义的，绝无获取用户密码的可能性，随机值的引入使hmac只在当前会话中有效，大大增强了安全性和实用性。