使用openssl库EVP编程计算md5值

参考openssl中的md5test.c

 

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

#include <openssl/evp.h>
#include <openssl/md5.h>
#include <openssl/err.h>

static char *test[] = {
	"",
	"a",
	"abc",
	"message digest",
	"abcdefghijklmnopqrstuvwxyz",
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
	"12345678901234567890123456789012345678901234567890123456789012345678901234567890",
	NULL,
};

static char *ret[] = {
	"d41d8cd98f00b204e9800998ecf8427e",
	"0cc175b9c0f1b6a831c399e269772661",
	"900150983cd24fb0d6963f7d28e17f72",
	"f96b697d7cb7938d525a2f31aaf161d0",
	"c3fcd3d76192e4007dfb496cca67e13b",
	"d174ab98d277d9f5a5611c2c9f419d9f",
	"57edf4a22be3c955ac49da2e2107b67a",
};

static char *pt(unsigned char *md)
{
	int i;
	static char buf[80];

	for (i = 0; i < MD5_DIGEST_LENGTH; i++)
		sprintf(&(buf[i * 2]), "%02x", md[i]);
	return (buf);
}

int main(void)
{
	int i;
	char **P, **R;
	char *p;
	unsigned char md[MD5_DIGEST_LENGTH];

	/* 遍历预设值校验 */
	P = test;
	R = ret;
	while (*P != NULL) {
		printf("calculating MD5 on '%s'\n", *P);
		EVP_Digest(&(P[0][0]), strlen((char *)*P), md, NULL, EVP_md5(),
			   NULL);
		p = pt(md);
		printf("MD5: %s\n", p);
		if (strcmp(p, (char *)*R) != 0) {
			printf("got %s instead of %s\n", p, *R);
		} else
			printf("test ok\n");
		printf("\n");
		R++;
		P++;
	}

	/* 命令行使用md5sum、openssl md5命令的时候会多计算一个'\n'换行符 */
	printf("calculating MD5 on '%s'\n", "abc\\n");
	printf("strlen %d\n", strlen("abc\n"));
	EVP_Digest("abc\n", strlen("abc\n"), md, NULL, EVP_md5(), NULL);
	p = pt(md);
	printf("%s\n", p);
	printf("\n");

	printf("echo abc | md5sum\n");
	system("echo abc | md5sum");
	printf("\n");

	/* 循环分段计算 */
	P = test + 5;
	printf("calculating MD5 on '%s'\n", *P);
	EVP_MD_CTX ctx;
	EVP_MD_CTX_init(&ctx);
	EVP_DigestInit_ex(&ctx, EVP_md5(), NULL);
	for (i = 0; i < strlen((char *)*P); i++) {
		EVP_DigestUpdate(&ctx, *P + i, 1);
	}
	EVP_DigestFinal_ex(&ctx, md, NULL);
	EVP_MD_CTX_cleanup(&ctx);
	p = pt(md);
	printf("%s\n", p);

	EVP_MD_CTX_init(&ctx);
	EVP_DigestInit_ex(&ctx, EVP_md5(), NULL);
	EVP_DigestUpdate(&ctx, "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
			 strlen("ABCDEFGHIJKLMNOPQRSTUVWXYZ"));
	EVP_DigestUpdate(&ctx, "abcdefghijklmnopqrstuvwxyz",
			 strlen("abcdefghijklmnopqrstuvwxyz"));
	EVP_DigestUpdate(&ctx, "0123456789", strlen("0123456789"));
	EVP_DigestFinal_ex(&ctx, md, NULL);
	EVP_MD_CTX_cleanup(&ctx);
	p = pt(md);
	printf("%s\n", p);

	ERR_load_crypto_strings();
	ERR_print_errors_fp(stderr);

	return 0;
}

 

运行结果

 

$ gcc -Wall -lcrypto md5.c

$ ./a.out 
calculating MD5 on ''
MD5: d41d8cd98f00b204e9800998ecf8427e
test ok

calculating MD5 on 'a'
MD5: 0cc175b9c0f1b6a831c399e269772661
test ok

calculating MD5 on 'abc'
MD5: 900150983cd24fb0d6963f7d28e17f72
test ok

calculating MD5 on 'message digest'
MD5: f96b697d7cb7938d525a2f31aaf161d0
test ok

calculating MD5 on 'abcdefghijklmnopqrstuvwxyz'
MD5: c3fcd3d76192e4007dfb496cca67e13b
test ok

calculating MD5 on 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
MD5: d174ab98d277d9f5a5611c2c9f419d9f
test ok

calculating MD5 on '12345678901234567890123456789012345678901234567890123456789012345678901234567890'
MD5: 57edf4a22be3c955ac49da2e2107b67a
test ok

calculating MD5 on 'abc\n'
strlen 4
0bee89b07a248e27c83fc3d5951213c1

echo abc | md5sum
0bee89b07a248e27c83fc3d5951213c1  -

calculating MD5 on 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
d174ab98d277d9f5a5611c2c9f419d9f
d174ab98d277d9f5a5611c2c9f419d9f