好久沒寫部落格了，直接上程式碼

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/x509.h>
#include <openssl/x509_vfy.h>
int LoadCert(unsigned char * szFilePath, unsigned char *pbCert, int size)
{
	int len = 0;
	if(szFilePath == NULL || pbCert == NULL || size < 128)
	{
		return -1;
	}
	FILE *fp = fopen(szFilePath, "rb");
	if ( NULL == fp)
	{
		return -2;
	}

	len = fread(pbCert, 1, size, fp);
	fclose(fp);
	return len;
}

int VerifyCert(unsigned char *pbCaCert, int nCaLen, unsigned char *pbCert, int nCertLen, unsigned char *pbCN, int size)
{
	int rv = -1;
	if(pbCaCert == NULL || nCaLen < 128 || pbCert == NULL || nCertLen < 128)
	{
		return rv;
	}

	X509 *ca = NULL;
	X509 *cert = NULL;

	X509_STORE *caStore = NULL;
	X509_STORE_CTX *ctx = NULL;
	X509_NAME *subject = NULL;
	
	OpenSSL_add_all_algorithms();

	caStore = X509_STORE_new();
	ctx = X509_STORE_CTX_new();

	ca = d2i_X509(NULL, ( const unsigned char **)&pbCaCert, nCaLen);
	if(ca == NULL)
	{
		return -2;
	}

	rv = X509_STORE_add_cert(caStore, ca);
	if ( rv != 1 )
	{
		rv = -3;
		goto EXIT_VERIFY;
	}

	cert = d2i_X509(NULL, ( const unsigned char **)&pbCert, nCertLen);
	if(cert == NULL)
	{
		rv = -4;
		goto EXIT_VERIFY;
	}

	rv = X509_STORE_CTX_init(ctx, caStore, cert, NULL);
	if ( rv != 1 )
	{
		rv = -5;
		goto EXIT_VERIFY;
	}

	rv = X509_verify_cert(ctx);
	if ( rv != 1 )
	{
		fprintf(stderr, "X509_verify_cert fail, rv = %d, error id = %d, %s\n",
		rv, ctx->error, X509_verify_cert_error_string(ctx->error));
		rv = (rv == 0 ? 1 : rv);
		goto EXIT_VERIFY;
	}
	subject = X509_get_subject_name(cert);
	if(subject)
	{
		X509_NAME_get_text_by_NID(subject, NID_commonName, pbCN, size);
	}
	rv = (rv == 1 ? 0 : rv);

EXIT_VERIFY:
	if(cert) X509_free(cert);
	if(ca) X509_free(ca);
	if(caStore) X509_STORE_free(caStore);
	if(ctx)
	{
		X509_STORE_CTX_cleanup(ctx);
		X509_STORE_CTX_free(ctx);
	}
	
	return rv;
}

int main(void)
{
	int rv = 0;
	int i = 0;
	int caLen = 0;
	int certLen =0;
	unsigned char cn[255] = {0};
	unsigned char cert[4096] = {0};
	unsigned char ca[4096] = {0};
	
	caLen = LoadCert("ca.cer", ca, 4096);
	certLen = LoadCert("Jinhill.cer", cert, 4096);
	rv = VerifyCert(ca, caLen, cert, certLen, cn, 255);
	printf("rv=%d, cn=%s\n", rv, cn);
	return 0;

}