【安全算法之SHA1】SHA1摘要运算的C语言源码实现

【安全算法之SHA1】SHA1摘要运算的C语言源码实现

• 概述
• 头文件定义
• C语言版本的实现源码
• 测试用例
• github仓库
• 更多参考链接

概述

大家都知道摘要算法在安全领域，也是一个特别重要的存在，而SHA1是其中比较常见的一种摘要算法，它的特点就是计算复杂度较低，不等长的数据原文输入，可以得出等长的摘要值，这个值是固定为20字节。正是由于这种特殊性，很多重要的数据完整性校验领域，都可以看到SHA1的影子。
今天给大家带来SHA1的C源码版本实现，欢迎大家深入学习和讨论。

头文件定义

头文件定义如下，主要定义了SHA1的上下文结构体，以及导出的三个API：

#ifndef __SHA1_H__
#define __SHA1_H__

#include 

#define SHA1_DIGEST_LEN 20         	// SHA1 outputs a 20 byte digest

typedef struct _sha1_ctx_t {
    uint32_t 		total[2];     	/*!< number of bytes processed  */
    uint32_t 		state[5];   	/*!< intermediate digest state  */
    uint8_t 		buffer[64];   	/*!< data block being processed */
} sha1_ctx_t;

void crypto_sha1_init(sha1_ctx_t *ctx);
void crypto_sha1_update(sha1_ctx_t *ctx, const uint8_t *data, uint32_t len);
void crypto_sha1_final(sha1_ctx_t *ctx, uint8_t *digest);

#endif   // __SHA1_H__

C语言版本的实现源码

下面是SHA1的C语言版本实现，主要也是围绕导出的3个API：

#include 
#include "sha1.h"

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n, b, i)                                              \
    {                                                                       \
        (n) = ((uint32_t)(b)[(i)] << 24) | ((uint32_t)(b)[(i) + 1] << 16) | \
              ((uint32_t)(b)[(i) + 2] << 8) | ((uint32_t)(b)[(i) + 3]);     \
    }
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n, b, i)                  \
    {                                           \
        (b)[(i)]     = (uint8_t)((n) >> 24);    \
        (b)[(i) + 1] = (uint8_t)((n) >> 16);    \
        (b)[(i) + 2] = (uint8_t)((n) >> 8);     \
        (b)[(i) + 3] = (uint8_t)((n));          \
    }
#endif

static const uint8_t sha1_padding[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

static void local_sha1_process(sha1_ctx_t *ctx,
                      const uint8_t   data[64])
{
    uint32_t temp, W[16], A, B, C, D, E;

    GET_UINT32_BE(W[0], data, 0);
    GET_UINT32_BE(W[1], data, 4);
    GET_UINT32_BE(W[2], data, 8);
    GET_UINT32_BE(W[3], data, 12);
    GET_UINT32_BE(W[4], data, 16);
    GET_UINT32_BE(W[5], data, 20);
    GET_UINT32_BE(W[6], data, 24);
    GET_UINT32_BE(W[7], data, 28);
    GET_UINT32_BE(W[8], data, 32);
    GET_UINT32_BE(W[9], data, 36);
    GET_UINT32_BE(W[10], data, 40);
    GET_UINT32_BE(W[11], data, 44);
    GET_UINT32_BE(W[12], data, 48);
    GET_UINT32_BE(W[13], data, 52);
    GET_UINT32_BE(W[14], data, 56);
    GET_UINT32_BE(W[15], data, 60);

#define S(x, n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define R(t)                                                             \
    (temp = W[(t - 3) & 0x0F] ^ W[(t - 8) & 0x0F] ^ W[(t - 14) & 0x0F] ^ \
            W[t & 0x0F],                                                 \
     (W[t & 0x0F] = S(temp, 1)))

#define P(a, b, c, d, e, x)                \
    {                                      \
        e += S(a, 5) + F(b, c, d) + K + x; \
        b = S(b, 30);                      \
    }

    A = ctx->state[0];
    B = ctx->state[1];
    C = ctx->state[2];
    D = ctx->state[3];
    E = ctx->state[4];

#define F(x, y, z) (z ^ (x & (y ^ z)))
#define K 0x5A827999

    P(A, B, C, D, E, W[0]);
    P(E, A, B, C, D, W[1]);
    P(D, E, A, B, C, W[2]);
    P(C, D, E, A, B, W[3]);
    P(B, C, D, E, A, W[4]);
    P(A, B, C, D, E, W[5]);
    P(E, A, B, C, D, W[6]);
    P(D, E, A, B, C, W[7]);
    P(C, D, E, A, B, W[8]);
    P(B, C, D, E, A, W[9]);
    P(A, B, C, D, E, W[10]);
    P(E, A, B, C, D, W[11]);
    P(D, E, A, B, C, W[12]);
    P(C, D, E, A, B, W[13]);
    P(B, C, D, E, A, W[14]);
    P(A, B, C, D, E, W[15]);
    P(E, A, B, C, D, R(16));
    P(D, E, A, B, C, R(17));
    P(C, D, E, A, B, R(18));
    P(B, C, D, E, A, R(19));

#undef K
#undef F

#define F(x, y, z) (x ^ y ^ z)
#define K 0x6ED9EBA1

    P(A, B, C, D, E, R(20));
    P(E, A, B, C, D, R(21));
    P(D, E, A, B, C, R(22));
    P(C, D, E, A, B, R(23));
    P(B, C, D, E, A, R(24));
    P(A, B, C, D, E, R(25));
    P(E, A, B, C, D, R(26));
    P(D, E, A, B, C, R(27));
    P(C, D, E, A, B, R(28));
    P(B, C, D, E, A, R(29));
    P(A, B, C, D, E, R(30));
    P(E, A, B, C, D, R(31));
    P(D, E, A, B, C, R(32));
    P(C, D, E, A, B, R(33));
    P(B, C, D, E, A, R(34));
    P(A, B, C, D, E, R(35));
    P(E, A, B, C, D, R(36));
    P(D, E, A, B, C, R(37));
    P(C, D, E, A, B, R(38));
    P(B, C, D, E, A, R(39));

#undef K
#undef F

#define F(x, y, z) ((x & y) | (z & (x | y)))
#define K 0x8F1BBCDC

    P(A, B, C, D, E, R(40));
    P(E, A, B, C, D, R(41));
    P(D, E, A, B, C, R(42));
    P(C, D, E, A, B, R(43));
    P(B, C, D, E, A, R(44));
    P(A, B, C, D, E, R(45));
    P(E, A, B, C, D, R(46));
    P(D, E, A, B, C, R(47));
    P(C, D, E, A, B, R(48));
    P(B, C, D, E, A, R(49));
    P(A, B, C, D, E, R(50));
    P(E, A, B, C, D, R(51));
    P(D, E, A, B, C, R(52));
    P(C, D, E, A, B, R(53));
    P(B, C, D, E, A, R(54));
    P(A, B, C, D, E, R(55));
    P(E, A, B, C, D, R(56));
    P(D, E, A, B, C, R(57));
    P(C, D, E, A, B, R(58));
    P(B, C, D, E, A, R(59));

#undef K
#undef F

#define F(x, y, z) (x ^ y ^ z)
#define K 0xCA62C1D6

    P(A, B, C, D, E, R(60));
    P(E, A, B, C, D, R(61));
    P(D, E, A, B, C, R(62));
    P(C, D, E, A, B, R(63));
    P(B, C, D, E, A, R(64));
    P(A, B, C, D, E, R(65));
    P(E, A, B, C, D, R(66));
    P(D, E, A, B, C, R(67));
    P(C, D, E, A, B, R(68));
    P(B, C, D, E, A, R(69));
    P(A, B, C, D, E, R(70));
    P(E, A, B, C, D, R(71));
    P(D, E, A, B, C, R(72));
    P(C, D, E, A, B, R(73));
    P(B, C, D, E, A, R(74));
    P(A, B, C, D, E, R(75));
    P(E, A, B, C, D, R(76));
    P(D, E, A, B, C, R(77));
    P(C, D, E, A, B, R(78));
    P(B, C, D, E, A, R(79));

#undef K
#undef F

    ctx->state[0] += A;
    ctx->state[1] += B;
    ctx->state[2] += C;
    ctx->state[3] += D;
    ctx->state[4] += E;
}

/*
 * SHA-1 process init
 */
void crypto_sha1_init(sha1_ctx_t *ctx)
{
    memset(ctx, 0, sizeof(sha1_ctx_t));
    ctx->total[0] = 0;
    ctx->total[1] = 0;

    ctx->state[0] = 0x67452301;
    ctx->state[1] = 0xEFCDAB89;
    ctx->state[2] = 0x98BADCFE;
    ctx->state[3] = 0x10325476;
    ctx->state[4] = 0xC3D2E1F0;
}

/*
 * SHA-1 process buffer
 */
void crypto_sha1_update(sha1_ctx_t *ctx, const uint8_t *input,
                     uint32_t ilen)
{
    uint32_t fill;
    uint32_t left;

    if (ilen == 0) {
        return;
    }

    left = ctx->total[0] & 0x3F;
    fill = 64 - left;

    ctx->total[0] += (uint32_t)ilen;
    ctx->total[0] &= 0xFFFFFFFF;

    if (ctx->total[0] < (uint32_t)ilen) {
        ctx->total[1]++;
    }

    if (left && ilen >= fill) {
        memcpy((void *)(ctx->buffer + left), input, fill);
        local_sha1_process(ctx, ctx->buffer);
        input += fill;
        ilen -= fill;
        left = 0;
    }

    while (ilen >= 64) {
        local_sha1_process(ctx, input);
        input += 64;
        ilen -= 64;
    }

    if (ilen > 0) {
        memcpy((void *)(ctx->buffer + left), input, ilen);
    }
}

/*
 * SHA-1 final digest
 */
void crypto_sha1_final(sha1_ctx_t *ctx, uint8_t *digest)
{
    uint32_t      last, padn;
    uint32_t      high, low;
    uint8_t msglen[8];

    high = (ctx->total[0] >> 29) | (ctx->total[1] << 3);
    low  = (ctx->total[0] << 3);

    PUT_UINT32_BE(high, msglen, 0);
    PUT_UINT32_BE(low, msglen, 4);

    last = ctx->total[0] & 0x3F;
    padn = (last < 56) ? (56 - last) : (120 - last);

    crypto_sha1_update(ctx, sha1_padding, padn);
    crypto_sha1_update(ctx, msglen, 8);

    PUT_UINT32_BE(ctx->state[0], digest, 0);
    PUT_UINT32_BE(ctx->state[1], digest, 4);
    PUT_UINT32_BE(ctx->state[2], digest, 8);
    PUT_UINT32_BE(ctx->state[3], digest, 12);
    PUT_UINT32_BE(ctx->state[4], digest, 16);
}

测试用例

针对SHA1导出的三个接口，我编写了以下测试用例：

#include 
#include 

#include "sha1.h"
#include "convert.h"

int log_hexdump(const char *title, const unsigned char *data, int len)
{
    char str[160], octet[10];
    int ofs, i, k, d;
    const unsigned char *buf = (const unsigned char *)data;
    const char dimm[] = "+------------------------------------------------------------------------------+";

    printf("%s (%d bytes):\r\n", title, len);
    printf("%s\r\n", dimm);
    printf("| Offset  : 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F   0123456789ABCDEF |\r\n");
    printf("%s\r\n", dimm);

    for (ofs = 0; ofs < (int)len; ofs += 16) {
        d = snprintf( str, sizeof(str), "| %08X: ", ofs );

        for (i = 0; i < 16; i++) {
            if ((i + ofs) < (int)len) {
                snprintf( octet, sizeof(octet), "%02X ", buf[ofs + i] );
            } else {
                snprintf( octet, sizeof(octet), "   " );
            }

            d += snprintf( &str[d], sizeof(str) - d, "%s", octet );
        }
        d += snprintf( &str[d], sizeof(str) - d, "  " );
        k = d;

        for (i = 0; i < 16; i++) {
            if ((i + ofs) < (int)len) {
                str[k++] = (0x20 <= (buf[ofs + i]) &&  (buf[ofs + i]) <= 0x7E) ? buf[ofs + i] : '.';
            } else {
                str[k++] = ' ';
            }
        }

        str[k] = '\0';
        printf("%s |\r\n", str);
    }

    printf("%s\r\n", dimm);

    return 0;
}

int main(int argc, const char *argv[])
{
	const char *data = "C1D0F8FB4958670DBA40AB1F3752EF0D";
    const char *digest_exp_str = "B36BFDB04A31F6C55E0D592B8F2D3219FBC2424D";
	uint8_t digest_calc[SHA1_DIGEST_LEN];
    uint8_t digest_exp_hex[SHA1_DIGEST_LEN];
	sha1_ctx_t ctx;
	const char *p_calc = data;
	uint8_t data_bytes[128];
	uint16_t len_bytes;
	char data_str[128];

	if (argc > 1) {
		p_calc = argv[1];
	}

	utils_hex_string_2_bytes(data, data_bytes, &len_bytes);
	log_hexdump("data_bytes", data_bytes, len_bytes);
	utils_bytes_2_hex_string(data_bytes, len_bytes, data_str);
	printf("data_str: %s\n", data_str);
	if (!strcmp(data, data_str)) {
		printf("hex string - bytes convert OK\n");
	} else {
		printf("hex string - bytes convert FAIL\n");
	}

	crypto_sha1_init(&ctx);
	crypto_sha1_update(&ctx, (uint8_t *)p_calc, strlen(p_calc));
	crypto_sha1_final(&ctx, digest_calc);

    utils_hex_string_2_bytes(digest_exp_str, digest_exp_hex, &len_bytes);
	if (len_bytes == sizeof(digest_calc) && !memcmp(digest_calc, digest_exp_hex, sizeof(digest_calc))) {
		printf("SHA1 digest test OK\n");
        log_hexdump("digest_calc", digest_calc, sizeof(digest_calc));
	} else {
		log_hexdump("digest_calc", digest_calc, sizeof(digest_calc));
		log_hexdump("digest_exp", digest_exp_hex, sizeof(digest_exp_hex));
		printf("SHA1 digest test FAIL\n");
	}

	return 0;
}

测试用例比较简单，就是对字符串C1D0F8FB4958670DBA40AB1F3752EF0D进行SHA1运算，期望的摘要结果的hexstring是B36BFDB04A31F6C55E0D592B8F2D3219FBC2424D，这个期望值是用算法工具算出来的。
先用API接口算出摘要值，再与期望值比较，这里有个hexstringtobyte的转换，如果比较一致则表示API计算OK；反之，接口计算失败。
同时，也欢迎大家设计提供更多的测试案例代码。

github仓库

以上代码和测试用例，及编译运行等，可以参考我的github仓库，有详细的流程介绍，欢迎大家交流讨论。如果有帮助到你的话，记得帮忙点亮一颗星哦。

更多参考链接

[1] 【安全算法的github仓库】
[2] 【安全算法之概述】一文带你简要了解常见常用的安全算法

审核编辑 黄昊宇