SHA-1_Algrithm_Analysis

#include
#include
#include
#include
#define SHA1HANDSOFF

typedef struct {
    u_int32_t state[5];        //A、B、C、D、E 寄存器
    u_int32_t count[2];
    unsigned char buffer[64];
} SHA1_CTX;
 
/****************************************************************************************************/
/*循环左移*/
#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))
 
/*Wt的计算*/
/*0<=t<=15,Wt = Message(t)*/
#if BYTE_ORDER == LITTLE_ENDIAN
    #define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#elif BYTE_ORDER == BIG_ENDIAN
    #define blk0(i) block->l[i]
#else
    #error "Endianness not defined!"
#endif
/*16<=t<=79*/
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))

/*SHA-1压缩函数中的单步迭代公式*/
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);
 
/****************************************************************************************************/
/* SHA-1算法核心——SHA-1压缩函数, Message_t：512bit的消息分组*/
 
void SHA1Transform(u_int32_t state[5], const unsigned char Message_t[64])
{
    u_int32_t a, b, c, d, e;
    typedef union {
        unsigned char c[64];    //处理char
        u_int32_t l[16];    //处理integer
    } CHAR64LONG16;

    #ifdef SHA1HANDSOFF
        CHAR64LONG16 block[1];  /* use array to appear as a pointer */
        memcpy(block, Message_t, 64);
    #else
    /* The following had better never be used because it causes the
    * pointer-to-const buffer to be cast into a pointer to non-const.
    * And the result is written through.  I threw a "const" in, hoping
    * this will cause a diagnostic.
    */
        CHAR64LONG16* block = (const CHAR64LONG16*)Message_t;
    #endif

    /* Copy context->state[] to working vars */
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    /* 4 rounds of 20 operations each. Loop unrolled. */
    R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
    R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
    R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
    R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
    R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
    R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
    R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
    R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
    R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
    R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
    R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
    R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
    R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
    R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
    R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
    R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
    R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
    R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
    R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
    R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);

    /* Add the working vars back into context.state[] */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;

    /* Wipe variables */
    a = b = c = d = e = 0;
    #ifdef SHA1HANDSOFF
        memset(block, '\0', sizeof(block));
    #endif
}
/****************************************************************************************************/
void SHA1Init(SHA1_CTX* context)
{
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}
/****************************************************************************************************/
/*SHA-1计算处理*/
void SHA1Update(SHA1_CTX* context, const unsigned char* data, u_int32_t datalen)
{
    u_int32_t i;
    u_int32_t j;

    j = context->count[0];

    /*处理2^64bit越界*/
    if ((context->count[0] += datalen << 3) < j)
        context->count[1]++;
    context->count[1] += (datalen>>29);
 
    j = (j >> 3) & 63;

    /*对每一个信息分组进行处理，不足64byte的是先填充后再在此计算*/
    if ((j + datalen) > 63) {
        memcpy(&context->buffer[j], data, (i = 64-j));
        SHA1Transform(context->state, context->buffer);
        for ( ; i + 63 < datalen; i += 64) {
            SHA1Transform(context->state, &data[i]);
        }
        j = 0;
    }
    else i = 0;
 
    memcpy(&context->buffer[j], &data[i], datalen - i);
}
/****************************************************************************************************/
/* SHA-1：填充步骤与信息摘要生成 */
void SHA1Final(unsigned char digest[20], SHA1_CTX* context)
{
    unsigned i;
    unsigned char finalcount[8];
    unsigned char c;
 
    /*finalcount[8]：存储Message长度*/
    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
        >> ((3-(i & 3)) * 8) ) & 255);
    }

    c = 0200;                    //0200->0x80:1000 0000
    SHA1Update(context, &c, 1);
    /*填充0*/
    while ((context->count[0] & 504) != 448) {    //504->0x1f8:0001 1111 1000
        c = 0000;                //448->0x1c0:0001 1100 0000
        SHA1Update(context, &c, 1);
    }
    /*填充Message长度*/
    SHA1Update(context, finalcount, 8);

    /*生成摘要*/
    for (i = 0; i < 20; i++) {
        digest[i] = (unsigned char)
        ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
    }

    /*擦除变量*/
    memset(context, '\0', sizeof(*context));
    memset(&finalcount, '\0', sizeof(finalcount));
}
/****************************************************************************************************/
 
#define BUFSIZE 4096
 
int
main(int argc, char **argv)
{
    SHA1_CTX ctx;
    unsigned char hash[20];
    int i;
    unsigned char * test = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";

    SHA1Init(&ctx);
    SHA1Update(&ctx, test, strlen(test));
    SHA1Final(hash, &ctx);
    printf("\n原字串:=%s\n",test);
    printf("SHA1=");
    for(i=0;i<20;i++)
        printf("%02x", hash[i]);
    printf("\n\n");
    return 0;
}

/****************************************************************************************************/

转自:http://hi.baidu.com/zhenxigly/blog/item/b75c4ddc65948553ccbf1a1e.html

SHA与MD5的比较

1.       最主要不同：SHA比MD5长32bits，抗攻击能力比较强。

2.       MD5已有密码分析的攻击法

3.       MD5效率比SHA高

4.       MD5采用小端格式，SHA则采用大端格式。

	轮数	每轮的次数	所有的次数	产生的bits	寄存器的个数
MD5	4	16	16*4= 64	32*4 = 128	A.B.C.D
SHA	4	20	20*4 = 80	32*5 = 160	A.B.C.D.E

/****************************************************************************************************/