使用openssl库EVP编程计算sha256值

参考sha256t.c

 

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

#include <openssl/sha.h>
#include <openssl/evp.h>

static char *s1 = "abc";
static char *s2 = "abcdbcde" "cdefdefg" "efghfghi" "ghijhijk"
    "ijkljklm" "klmnlmno" "mnopnopq";

static unsigned char app_b1[SHA256_DIGEST_LENGTH] = {
	0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
	0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
	0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
	0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad
};

static unsigned char app_b2[SHA256_DIGEST_LENGTH] = {
	0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
	0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
	0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
	0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1
};

static unsigned char app_b3[SHA256_DIGEST_LENGTH] = {
	0xcd, 0xc7, 0x6e, 0x5c, 0x99, 0x14, 0xfb, 0x92,
	0x81, 0xa1, 0xc7, 0xe2, 0x84, 0xd7, 0x3e, 0x67,
	0xf1, 0x80, 0x9a, 0x48, 0xa4, 0x97, 0x20, 0x0e,
	0x04, 0x6d, 0x39, 0xcc, 0xc7, 0x11, 0x2c, 0xd0
};

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

	for (i = 0; i < SHA256_DIGEST_LENGTH; i++)
		sprintf(&(buf[i * 2]), "%02x", md[i]);
	return (buf);
}

int main(int argc, char *argv[])
{
	unsigned char md[SHA256_DIGEST_LENGTH];
	int i;
	EVP_MD_CTX evp;
	char *p;

	if (argc > 1) {
		printf("calculating SHA256 on '%s'\n", argv[1]);
		EVP_Digest(argv[1], strlen(argv[1]), md, NULL, EVP_sha256(),
			   NULL);
		p = pt(md);
		printf("SHA256: %s\n", p);
		return 0;
	}

	printf("calculating SHA256 on '%s'\n", s1);
	EVP_Digest(s1, strlen(s1), md, NULL, EVP_sha256(), NULL);
	p = pt(md);
	printf("SHA256: %s\n", p);
	if (memcmp(md, app_b1, sizeof(app_b1))) {
		printf("\nTEST 1 of 3 failed.\n");
		return 1;
	} else
		printf(".\n");

	printf("calculating SHA256 on '%s'\n", s2);
	EVP_Digest(s2, strlen(s2), md, NULL, EVP_sha256(), NULL);
	p = pt(md);
	printf("SHA256: %s\n", p);
	if (memcmp(md, app_b2, sizeof(app_b2))) {
		printf("\nTEST 2 of 3 failed.\n");
		return 1;
	} else
		printf(".\n");

	printf("calculating SHA256 on 'a' * 1000000\n");
	static unsigned char buf[160];
	memset(buf, 'a', 160);
	EVP_MD_CTX_init(&evp);
	EVP_DigestInit_ex(&evp, EVP_sha256(), NULL);
	for (i = 0; i < 1000000; i += 160)
		EVP_DigestUpdate(&evp, buf,
				 (1000000 - i) < 160 ? 1000000 - i : 160);
	EVP_DigestFinal_ex(&evp, md, NULL);
	EVP_MD_CTX_cleanup(&evp);
	p = pt(md);
	printf("SHA256: %s\n", p);
	if (memcmp(md, app_b3, sizeof(app_b3))) {
		printf("\nTEST 3 of 3 failed.\n");
		return 1;
	} else
		printf(".\n");

	return 0;
}

 

运行结果

 

$ gcc -Wall -lcrypto sha256.c

$ ./a.out 
calculating SHA256 on 'abc'
SHA256: ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad
.
calculating SHA256 on 'abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq'
SHA256: 248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1
.
calculating SHA256 on 'a' * 1000000
SHA256: cdc76e5c9914fb9281a1c7e284d73e67f1809a48a497200e046d39ccc7112cd0
.

$ ./a.out abc
calculating SHA256 on 'abc'
SHA256: ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad